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BERT Technical Articles

GB1400 User Manual

B-31

A BERT designed to measure jitter has a phase demodulator

 

connected to the covered clock. The range of

f

m

 is from f

1

=10 Hz to f

4

; the amplitude depends on f

m.

The BERT’s jitter generation and jitter measurements specifications should be somewhat higher than the
maximum jitter that a system can typically tolerate. As a result, a BERT with jitter generation can find a
receiver’s 

θ

e max

 by setting f

m

=f

4

 and increasing A until the receiver begins to make errors. In addition, the

clock-recovery bandwidth, f

B

, can be estimated by lowering f

m

 until the jitter tolerance begins to exceed

θ

e max.

BERT Affects Accuracy

Several BERT characteristics can affect the accuracy of system measurements.  For instance, a BERT
transmitter may have a very jittery clock source, such as an open-loop voltage-controlled oscillator.  If so,
the system will have a higher error rate or less margin than when the system’s clock source is used.
Measuring the clock-source spectral density and calculation 

θ

e rms

 will uncover this problem.

Another snag may be that a BERT receiver has a very narrowband clock-recovery circuit, such as crystal
controlled phase locked loop.  The small f

B

 will probably make the BERT less tolerant of jitter than the

system its testing.  In high jitter situations, therefore, the BERT will report a higher bit error rate than the
actual rate.  A BERT transmitter with jitter generation can measure its own receiver’s jitter tolerance and
that of the system to see which is greater.

The question of whether a BERT data pattern fairly represents live traffic is more difficult to answer.
Experience indicates that long PRBS patterns (N greater than 14 ) stress the system more than most live
traffic does.  But it is rare traffic with unusually stressing patterns that is most interesting.  Therefore, the
best users can do is to anticipate these patterns and generate them with fixed patterns from the BERT
transmitter.

============

Содержание gigaBERT1400

Страница 1: ... gigaBERT1400 1400 Mb s Bit Error Rate Tester Generator and Analyzer 071 0590 00 This document supports firmware version 2 2 and above Advanced Test Equipment Rentals www atecorp com 800 404 ATEC 2832 Established 1981 ...

Страница 2: ... ii of the Rights in Technical Data and Computer Software clause at DFARS 252 227 7013 or subparagraphs c 1 and 2 of the Commercial Computer Software Restricted Rights clause at FAR 52 227 19 as applicable Tektronix products are covered by U S and foreign patents issued and pending Information in this publication supersedes that in all previously published material Specifications and price change ...

Страница 3: ...returned to any other locations This warranty shall not apply to any defect failure or damage caused by improper use or improper or inadequate maintenance and care Tektronix shall not be obligated to furnish service under warranty a to repair damage resulting from attempts by personnel other than Tektronix representatives to install repair or service the product b to repair damage resulting from i...

Страница 4: ...on applications operation measurement specifications hardware and software by expert application engineers For Applications Support call the Customer Support Center listed below Mailing Address Tektronix Inc Measurement Business Division P O Box 500 Beaverton Oregon 97077 0001 USA Attn Customer Service Customer and Sales Support Center 800 TEK WIDE or 800 835 9433 Ext 2400 Hours are 6 00 AM to 5 0...

Страница 5: ...2 9 Generator OUTPUT 2 9 Generator CLOCK 2 10 Generator OUTPUT Set up 2 11 Generator Rear Panel 2 12 Changing the Line Fuse 2 12 Analyzer INPUT 2 13 Analyzer MONITOR 2 14 Analyzer Rear Panel 2 15 Changing the Line Fuse 2 15 Connectors Terminations and Levels 2 16 Controls Indicators 2 18 Power Switches 2 18 Unit Mounting 2 18 Unit Cooling 2 18 View Angle and Panel Lock Keys 2 18 Reset to Factory D...

Страница 6: ...ponent Test 2 46 Fibre Channel Link Testing Parallel and High Speed Serial 2 47 Testing QPSK Modems I Q 2 48 QPSK BER Testing using PRBS Data for 2 Channel I Q 2 49 Reference Menu Overview 3 1 Functions common to TX and RX 3 1 AC Power 3 1 Selecting 115 VAC or 230 VAC operation 3 1 Turning Instrument Power ON OFF 3 1 LCD Viewing Angle 3 1 Recalling Default Setup 3 2 Locking the Front Panel 3 2 Sel...

Страница 7: ...Amplitude and Baseline Offset 3 14 Logically Inverting Output Data D INV 3 15 Single Ended or Differential Operation 3 16 Pattern SYNC PYNC and CLOCK 4 Outputs 3 16 Error Injection 3 17 Selection an Error Inject Mode 3 17 Error INJECT Input 3 18 Analyzer Functions 3 19 Automatic Setup Functions SYNC 3 19 AUTO SEARCH with PRBS Patterns 3 20 AUTO SEARCH with Non PRBS Patterns 3 21 How to DISABLE Aut...

Страница 8: ...ions 3 42 Error History Indicators 3 44 CLEAR Control 3 45 Audio Beeper Function 3 45 Analyzer Error Messages 3 45 Starting Stopping Measurements 3 46 Menus 3 48 Functions Performed using the Menu System 3 48 Menu and Function Pages 3 48 General Rules for using the Menu System 3 51 Menu Summaries 3 52 Menu Function Definitions 3 55 Word Edit EDIT 3 56 Word Length LENGTH 3 57 Word Fill FILL 3 58 Wo...

Страница 9: ...RITY 3 76 RS 232 Data Bits SIZE 3 77 RS 232 End of Line Char EOL 3 78 RS 232 Xon Xoff XON XOFF 3 79 RS 232 Echo ECHO 3 80 GPIB 3 81 Utility Option OPTION 3 82 Utility Version VER 3 83 Time Option DATE 3 84 Time Option TIME 3 85 Appendices Specifications A 1 BERT Primer Technical Articles B 1 Remote Commands C 1 Using GPIB RS 232 D 1 Customer Acceptance Test E 1 Default Settings F 1 Cleaning Instru...

Страница 10: ...28 2 10 Receiver Burst Mode Operation 2 28 3 1 Nominal Generator Clock Data Waveforms showing Amplitude Baseline Offset and Vtop 3 13 3 2 Generator Clock and Data Output Equivalent Circuits 3 17 3 3 Analyzer Clock and Data Input Equivalent Circuits 3 22 3 4 TOTALIZE Measurement Process 3 30 3 5 WINDOW Measurements Process 3 31 3 6 TEST Measurement Process 3 32 B 1 Three stage PRBS generator B 5 B ...

Страница 11: ...t 3 20 3 5 Synchronization Threshold 3 22 3 6 How F2 F3 determine Input Set up 3 24 3 7 Input Terminations for CLOCK DATA and REF DATA 3 25 3 8 Input Threshold Range as a Function of Termination 3 26 3 9 How to Tell which Display Mode is Active 3 37 3 10 Menu Descriptions 3 52 3 11 Analyzer Menu System Overview 3 53 3 12 Generator Menu System Overview 3 54 B 1 PRBS Polynomials and Shift Register f...

Страница 12: ... and ground Ground the Instrument The GB1400 is grounded through its AC power cord Plug this power cord only into a properly grounded three conductor outlet If you operate the instrument without a proper ground then all metal surfaces on the instrument become potential shock hazards To avoid potential hazards use this product only as specified Use the Proper Fuse Operating the instrument with an i...

Страница 13: ...urate to their specified positive or negative rail that is 2 V or 2 V for up to 400 milliseconds If this condition could be harmful to your equipment then remove all connections to your GB1400 Generator CLOCK and DATA outputs before powering or de powering the instrument Unit Mounting The GB1400 is designed to be placed 1 flat on a level surface capable of supporting its weight or 2 angled from th...

Страница 14: ...n note in this section Reference describes the LCD Menus and Screens The Appendices provide a listing of specifications a BERT technology primer Theory of Operation Remote Commands default factory settings an extensive Customer Acceptance Test and other useful information Conventions This manual uses the following conventions The names of front panel controls and menus appear in all upper case let...

Страница 15: ... GB1400 User Manual xv Related Manuals The following document is also complementary to the GB1400 The GB700 BER Tester User Manual Tektronix part number 070 9393 02 describes how to operate the GB700 test set ...

Страница 16: ...Preface GB1400 User Manual xvi ...

Страница 17: ...Getting Started ...

Страница 18: ...ile primarily a lab instrument the GB1400 s compact design full computer programmability and relatively light weight also enable it to serve in manufacturing ATE and field test applications The quality of a digital link depends on many factors but everything comes down to the issue of whether the circuit exhibits a satisfactory BER bit error rate and has sufficient margin to function under stress ...

Страница 19: ...l Ethernet Digital Video MPEG SDV HDDV Wideband Satellite Data Links SONET SDH Network Devices up to OC 12e STM4e High speed GaAs ECL E O device testing Test Clock Recovery Circuits Parallel to Serial Analysis with Tektronix MB100 Testing of High Speed Fibre Channel links up to 1 063 Mb s Gigabit Ethernet at 1 250 Mb s Testing of high speed Optical Busses Opto Bus Opto Bahn at 800 Mb s per channel...

Страница 20: ...BER is calculated from the last power on or reset Window BER is calculated over a sliding window specified in terms of time 1 second to 24 hours or bits 18 to 116 bits Test BER is calculated from the start of the current test A hard copy of all test results can be generated locally by connecting a printer to the parallel printer port or GPIB or RS 232 port Reports may be printed when an error is d...

Страница 21: ... rackmount kits Opt A3 Australian 240 V 50 Hz gB1400T 1400 Mb s BERT Pattern Generator Opt 02 75 Ohm Pattern Generator Only Opt 05 BURST Mode Pattern Generator Only Opt 07 Positive ECL Pattern Generator Only Opt 08 1 Mbit RAM WORD Generator Only w PC Pattern Edit software Opt 1M Rack Mount Opt A3 Australian 240 V 50 Hz gB1400R 1400 Mb s BERT Error Detector Opt 02 75 Ohm Error Detector Only Opt 05 ...

Страница 22: ... 17 20 23 Burst Mode New Line External Clk Only Standard Feature Standard Feature Optional Feature Receiver Frequency range w Burst Mode 1 150 kHz to 705 MHz 150 kHz to 705 MHz 150 kHz to 705 MHz 150 kHz to 705 MHz 1 MHz to 1405 MHz 150 kHz to 1405 MHz Burst Mode Ext Clk Only Standard Feature Standard Feature Optional Feature Clock Data Input levels max 500 mV to 6 0 V p p 500 mV to 6 0 V p p 500 ...

Страница 23: ...ators no burst option have an AC coupled external clock input All standard configuration GB1400 Analyzers no burst option have AC coupled paths in the receiver clock input circuitry GB1400 with Burst Option When the BURST option is installed in the GB1400 the AC coupled paths in both transmitter and receiver are eliminated This will also change several specifications listed in the table below Exte...

Страница 24: ...lyzer DATA input 6 Connect a 50 Ohm SMA cable from the Analyzer rear panel DATA THRESHOLD output to the Analyzer DATA BAR input required for single ended data inputs 7 Power the Generator while pressing and holding its VIEW ANGLE MSB 1 and PATTERN CLEAR keys simultaneously Release the key after the message Default Settings appears in the display Repeat this procedure with the Analyzer This will fo...

Страница 25: ...een LOCK LED in the Analyzer SYNC box is on 12 Zero all Analyzer error counts by pressing CLEAR in the ERROR DETECTION group 13 Reset all Analyzer history LEDs by pressing CLEAR in the ERROR HISTORY group 14 Verify GB1400 Analyzer can detect errors by pressing the Generator error inject SINGLE key several times Verify that the Number of Errors count displayed by the Analyzer increments each time t...

Страница 26: ...Operating Basics ...

Страница 27: ...the GB1400 including BERT Basics Controls indicators and connectors Display Formats Outputs and Inputs Also in this section is Tutorial Understand GB1400 instrument setup for BER testing using PRBS patterns Application Note Auto Search Synchronization with GB1400 and Application Example GB700 GB1400 Optical component test ...

Страница 28: ...tal path at a time The term serial also distinguishes the GB1400 from parallel BERTs such as the Tektronix MB100 which is designed to test multiple digital signal paths simultaneously The GB1400 Generator also known as the transmitter or Tx can generate various test patterns including pseudo random bit sequences PRBS and user defined word patterns The Generator output consists of a two level non r...

Страница 29: ...bility with a wide range of input circuit designs and logic families including ECL positive ECL and GaAs The GB1400 Analyzer also known as the receiver or Rx can terminate and analyze the NRZ output of a digital device module or system being tested by the GB1400 Generator or an equivalent signal source The decision voltage or threshold of the Analyzer DATA and CLOCK inputs can be adjusted to accom...

Страница 30: ... FUSES INPUT MAX LINE VOLTAGE RANGE POWER FUSE 115 90 132V 175W 5A SLOBLO 230 180 250V 175W 5A SLOBLO AUTO SELECT FREQUENCY 47 63 Hz PHASE A PHASE B CLOCK 2 ERROR INJECT DATA INHIBIT Figure 2 4 Rear Panel GB1400 Generator Tx FREQUENCY kHz PATTERN OUTPUT AMPL OFFSET RATE SINGLE CLOCK PATTERN OUTPUT OUTPUT ERROR INJECT FREQUENCY STEP RECALL SAVE EXT PRBS WORD RECALL SAVE F1 F2 F3 F4 MSB 1 2 3 4 5 6 ...

Страница 31: ...0 Ohm SOURCE 50 Ohm 1 5V MAX 50 Ohm 2V MAX DELAY MEMORY 1 With Option 2 this input is 75 Ohm 2 With Option 5 the input is ECL levels only 1 2 1 BIT CLK REF Figure 2 5 Front Panel GB1400 Analyzer RX PRINTER DATA THRESHOLD ERROR INHIBIT RZ ERROR OUTPUT RS 232C GPIB AC LINE WARNING ELECTRICAL SHOCK HAZARD THIS INSTRUMENT MUST BE GROUNDED DO NOT OPEN INSTRUMENT REFER SERVICING TO QUALIFIED PERSONNEL D...

Страница 32: ...ow The top left section of the Generator display is used to show the current frequency of the internal clock in MHz For example a display of 6 2 2 0 5 0 indicates a frequency of 622 050 MHz The top middle section normally shows the current test pattern For example PN23 INV indicates that the current pattern is an inverted 223 1 PRBS The top right section of the display shows the amplitude of the C...

Страница 33: ...he Analyzer frequency display contains five significant digits while the Generator frequency display contains six This is because the frequency shown in the Analyzer display is a measurementresult while the frequency shown in the Generator display is an instrumentsetup which is known with more precision The top middle and top right sections of the display normally show measured bit error rate and ...

Страница 34: ...The status of each key LED and LCD displayed value now reflects the CLOCK Input signal Pressing F3 places the unit into REF Data control mode F3 LED illuminated The Delay V TERM and V THRS keys are redefined to allow control of the Input REF DATA Delay Termination Volga and Threshold The status of each key LED and LCD displayed value now reflects the REF DATA Input signal The bottom middle section...

Страница 35: ... Connectors Generator OUTPUT Connectors Section The OUTPUT connectors section of the Generator front panel contains the outputs listed below CLOCK and DATA outputs These two connectors comprise the main test signal output of the Generator DATA is the NRZ output of the pattern generator and CLOCK is its corresponding clock signal The amplitude and baseline offset of CLOCK and DATA are variable CLOC...

Страница 36: ... clock The CLOCK section also contains the input connector for an external clock source These controls and input are introduced below FREQUENCY STEP RECALL SAVE EXT INPUT 50 Ohm 2 V Max 2 FREQUENCY When this key is selected LED on the clock up down keys may be used to adjust the frequency of the internal Generator clock up or down Each press of the frequency up or down key will increment or decrem...

Страница 37: ...e and offset set up mode DATA Use this key to select data amplitude and offset set up mode AMPLITUDE Use these up down keys to adjust clock or data output amplitude BASELINE OFFSET Use these up down keys to adjust clock or data baseline offset INVERT DATA Use this key to toggle between output data inverted LED on and non inverted LED off mode OUTPUT CLOCK DATA AMPLITUDE OFFSET INVERT DATA D INV ...

Страница 38: ...external EXT ERR injection mode One error will occur for each rising edge of this signal DATA INHIBIT An ECL signal applied to this input may be used to asynchronously gate off the data outputs of the Generator RS 232C input output A two way serial port that may be connected to an external controller or serial printer GPIB input output An IEEE 488 standard I O port that may be connected to a GPIB ...

Страница 39: ...TA input Only the unused DATA BAR input needs the threshold signal The CLOCK input is self biasing for single ended applications CLOCK BAR and DATA BAR inputs These are complimentary inputs to CLOCK and DATA That is CLOCK and CLOCK BAR together comprise a differential clock input while DATA and DATA BAR together comprise a differential data input When the Analyzer is connected to singled ended clo...

Страница 40: ... as seen by the Analyzer CLOCK output A buffered copy of the clock signal received by the Analyzer DATA output A regenerated re clocked version of the data signal received by the Analyzer PATTERN SYNC output A train of pulses that occur once per pattern frame This output may be used to trigger an oscilloscope to view the beginning first bit byte of the data pattern PATTERN SYNC CLOCK DATA MONITOR ...

Страница 41: ...n ECL output signal One pulse will be generated at this output for each bit error detected May be connected to an external recording device for example to log the exact times that errors occur PRINTER output A one way port that may be connected to a parallel printer that is any printer compatible with the parallel port LPT1 etc of an IBM compatible PC RS 232 C input output A two way serial port th...

Страница 42: ...SMA female 50 Ohm see NOTE 1 variable amplitude and offset CLOCK BAR output OUTPUT section SMA female 50 Ohm see NOTE 1 variable amplitude and offset CLOCK 4 output OUTPUT section SMA female 50 Ohm 200mV into 50Ω PATTERN SYNC output OUTPUT section SMA female 50 Ohm 200mV into 50Ω CLOCK INPUT input CLOCK section SMA female 50 Ohm 2V max see NOTE 2 DATA INHIBIT input rear panel BNC female 50 Ohm to ...

Страница 43: ... female 50 Ohm ECL variable delay selectable termination GND 2V AC PATTERN SYNC output MONITOR SMA female 50 Ohm 200mV into 50Ω CLOCK output MONITOR SMA female 50 Ohm 200mV into 50Ω DATA output MONITOR SMA female 50 Ohm 200mV into 50Ω ERROR INHIBIT INPUT input rear panel BNC female 50 Ohm ECL RZ ERROR OUTPUT output rear panel BNC female 50 Ohm 200mV into 50Ω PRINTER output rear panel 25 pin D male...

Страница 44: ...the unit on a work surface A Rack mounting option is available for installation of the unit into a 19 rackmount The rack height for the GB1400 is 7 inches four RMU Unit Cooling The rear panel fan openings must be kept clear for proper cooling of the unit Allow a minimum of two 2 inches of rear panel clearance and one 1 inch of top clearance while operating the unit View Angle and Panel Lock Keys T...

Страница 45: ...whether the instrument is in the local mode LED off or remote mode LED on If the LED is on you can return the instrument to local mode by pressing the LOCAL key Note that these two keys are used only when operating the instrument via its GPIB port For more information on the GPIB port and remote control in general see the appendix For detailed descriptions of all remote commands see the appendix ...

Страница 46: ...RD Press this key either to select a word or ROM pattern or to edit the current word pattern SAVE and RECALL Use these keys to save and recall user created word patterns to and from non volatile memory The standard GB1400 can store up to ten 16 bit or short word patterns When equipped with the 1 Mbit option the GB1400 Generator and Analyzer can store up to ten 10 65 kbit patterns depending upon th...

Страница 47: ...e Input parameters for Reference DATA DELAY Pressing DELAY selects Input Data Delay adjust mode The Input Data signal can be delayed over the range 0 0 nS to 3 9 nS in sub nanosecond steps The delay is modified with the INPUT Up Down keys The current Delay is displayed on the lower left side of the LCD An illuminated Delay LED light indicates that the unit s DELAY can be modified by the Up Down ar...

Страница 48: ...ternal error inject mode SINGLE When the error inject function is set to single ERR OFF press this key to inject single errors Or when the error inject function is set to an internal rate or to external use this key to turn error injection off Note that you could then press the RATE key to turn error injection back on at the same rate as before Error Inject LED The LED in the ERROR INJECT section ...

Страница 49: ...put decision threshold for the DATA and REF DATA inputs Note that threshold does not apply when differential operation is selected Function keys F2 and F3 are OFF when programming DATA Function key F3 is ON when programming REF DATA V TERM Press this key to select the input terminations for the DATA CLOCK or REF DATA inputs Available selections are GND 2 V or AC See table below D INV Press this ke...

Страница 50: ... cleared by the user PHASE The PHASE LED is lit when the guaranteed setup or hold time of the GB1400 input decision circuit is violated This indicates to the user that the errors that are occurring may be due to input clock data timing or signal level POWER The POWER LED is lit when the unit powers up It remains lit until it is cleared by the user It is used to indicate that the unit lost power du...

Страница 51: ...ime BER goes above the synchronization threshold LOCK LED turns off the Analyzer will automatically attempt to 1 set the decision level for the DATA inputs 2 set input DATA delay 3 determine which PRBS or short word pattern is being received and 4 determine if the pattern is inverted or not DISABLE Use this key to enable or disable automatic pattern re synchronization If DISABLE is off then the An...

Страница 52: ...e still present Note The Clock may be used either differentially or single ended To use a single ended clock input connect the ECL clock input to the CLOCK input connector Select the 2V input termination and connect DC bias voltage of 1 3 VDC to the CLOCK BAR input connector These and other changes will now allow the receiver to maintain synchronization whenever CLOCK and DATA are synchronously st...

Страница 53: ...ge many bits in the burst would not be checked during the re synchronization procedure In Burst Mode the GB1400 RX will follow the input CLOCK and DATA without regard for inactive time between bursts The only requirement is that there be no bit slips between the CLOCK and DATA at the Tx or UUT and there be a clock cycle for every DATA bit received See figures on the next page for Transmit and Rece...

Страница 54: ...Ext Clk In Clk Out Data Out Data Value 1 0 1 1 0 0 Figure 2 9 Transmitter Burst Mode Option A DATA B DATA C DATA Sync Time Measurement Undefined Time Sync Attained Msmt Measurement Msmt Msmt Sync Measurement Start Resync Sync Attained Figure 2 10 Receiver Burst Mode Operation ...

Страница 55: ...ting 5 0 V above ground Example ECL Levels PECL Levels VOH 9V VOH 4 1V VOL 1 8V VOL 3 2V VBB 1 35V VBB 3 65V VTT 2 0V VTT 3 0V The GB1400 front panel displays the clock and data amplitude and offset based on a load of 50 Ohms to ground The inverted output circuit is identical to the true output circuit In the PECL system Vtt 3 0V therefore the resulting GB1400 Tx signal will be shifted by 1 5V To ...

Страница 56: ...and GB1400 instrument setup for BER testing using PRBS patterns Procedure This tutorial programs the GB1400 Generator to provide PRBS clock and data signals for the Analyzer Using AUTO SEARCH features the Analyzer will synchronize to the incoming PRBS test pattern Bit Error Rate BER measurements will be performed on both good error free and bad user injected faults data streams Key Feature of Tuto...

Страница 57: ...s on this beginners lab A customer would not normally do this as they would lose their stored setups To reset the units to their factory default setting you must hold down three separate keys while turning on the front panel power switch Power the Generator while pressing and holding its VIEW ANGLE MSB 1and PATTERN CLEAR keys simultaneously Release the key after the message Default Settings appear...

Страница 58: ...p the clock not_clock data and not_data signals or tutorial results will be different 3 Setup Generator for PRBS 23 Mode Locate the controls in the OUTPUT box of the Generator Setup the Generator clock and data outputs as follows Set this parameter to this value using this procedure DATA amplitude 1 volts Press the DATA key The LED within the switch should be lit Press AMPLITUDE up down keys until...

Страница 59: ...ocate the controls in the ERROR DETECTION box of the Analyzer Zero all Analyzer error counts by pressing the CLEAR key Confirm that the number of errors and the error rate were reset to 0 note error rate will start changing as more and more bits are received After several minutes of operation the error rate should reach 0 0E 9 0 0E 10 0 0E 11 and on C Locate the controls in the ERROR HISTORY box o...

Страница 60: ...yzer error counts by pressing the CLEAR key C Locate the controls in the ERROR HISTORY box of the Analyzer Reset all Analyzer history LEDs by pressing this CLEAR key Confirm that all ERROR HISTORY LED s are turned OFF D Locate the controls in the ERROR INJECT box of the Generator Press the ERROR INJECT SINGLE key several times Verify that the error count displayed by the Analyzer increments each t...

Страница 61: ...hreshold is 0 00Vdc 0 05Vdc You will now be manually adjusting the data input threshold for the GB1400 Analyzer Locate the controls in the PATTERN box of the Analyzer Make sure F2 and F3 are turned OFF These switches are used when adjusting CLOCK or REF DATA input parameters C Locate the controls in the INPUT box of the Analyzer Verify that the Analyzer THRESH LED is turnedON This allows manual ad...

Страница 62: ...our data signal Data threshold is NOT CORRECT and you should expect BER errors 0 00 volts Press the ERROR DETECTION and ERROR HISTORY CLEAR KEYS then confirm SYNC LOSS should turn OFF BIT and PHASE LED s should turn OFF SYNC LOCK LED should turn ON ERROR RATE display shows NO BER ERRORS equivalent to a rate of 0 0E 9 or better Data signal fully detected Selected threshold is at an optimum value fo...

Страница 63: ...he value of the threshold selected by Auto Search You should expect to see this threshold value within a few hundred millivolts of the data signal mid point or optimum threshold Note Common Setup Problems Connecting the Generator s clock output to the Analyzer s not clock clock bar input Connecting the Generator s data output to the Analyzer s not data data bar input Changing Generator s CLOCK amp...

Страница 64: ...f data and its quality Analysis of the input data signal amplitude to select the correct threshold voltage Determine the timing skew between the clock and data signals and automatically optimize it Determine the correct data sequence and whether it is inverted Measure the data eye width So that the following explanations are clear let us first define some terms V THRESHOLD This is the absolute DC ...

Страница 65: ...e SYNCHRONIZATION When we state that the receiver is synchronized we mean that the GB1400 Receiver s internal reference data pattern generator is bit for bit properly aligned with the incoming data from the device under test When in synchronization the receiver can perform a bit for bit check of the incoming data against its internal reference to determine bit errors DATA POLARITY This refers to w...

Страница 66: ...Application Note Auto Search Synchronization 2 40 GB1400 User Manual ...

Страница 67: ... then locates and uses the middle of the largest voltage range which has data activity If no activity is detected or if the range of activity is less than 250 mV then the receiver indicates NO DATA has been detected Auto Search will find the DATA DELAY 1 For each delay setting the receiver keeps track of the PHASE indication 2 It then locates the largest contiguous block of delay settings without ...

Страница 68: ...h the SAMPLE and BER THRESHOLD criteria requirements in the BER method if selected intelligently tend to yield more accuracy and repeatability and is less subject to glitches noise and jitter than the FAST method The Auto Search BER method of determining the proper settings of the V Threshold Patter Polarity and Delay is as follows Auto Search will find the DATA V THRESHOLD voltage 1 The receiver ...

Страница 69: ...set the delay to the middle of the receiver delay range STOP No eye width is available If ONE end of the clear block is on the edge and the width of the clear block is less than half the clock period set the delay to that edge STOP No eye width is available If ONE end of the clear block is on the edge and the width of the clear block is greater than half the clock period two transition points A an...

Страница 70: ...3 the delay will be set to be away from the middle of the TRUE transition points by half the data clock period point C 7 Eye Width Measurement In the previous step above if the error rate is below the threshold the measured eye width is the point B delay measurement minus the point A delay measurement in Diagram 1 Case 1 STOP In the previous step above if the error rate is above the threshold the ...

Страница 71: ...00 Receiver to duplicate all characteristics of the actual device that will be connected in its place but it will usually suffice as a reasonable approximation Consideration In Determining The Data Eye Center In theory a plot of bit error versus delay setting will show a smooth curve almost linear which has no aberrations and transitions from horizontal to almost vertical at the data eye crossing ...

Страница 72: ...rial digital video links operate at 270 Mb s External Clock input shown on the BERT Tx would be used to provide jittered clock to stress Clock Recovery CR circuit Longer PRBS patterns such as 223 might be used to test DC wander susceptibility of the CR subsystem Peak to peak amplitude and level offset of the BERT Tx output may be varied to determine acceptable operating range for the DUT input cir...

Страница 73: ... Example Fibre Channel Link Testing Parallel and High speed Serial BUS Interface BUS Interface gigaBERT Serial E O BUS Serial Serial BUS Fiber Interface Under Test Tx Rx gigaBERT Serial Tx Tx Rx Rx O E Parallel stimulus Parallel results ...

Страница 74: ... Application Example Testing QPSK Modems I Q QPSK Mod Demod up to 1400 Mb s data rate I Q I Q GB700 1400 Tx DATA CLOCK GB700 1400 Rx data clock GB700 1400 Rx data clock I Channel BERT Q Channel BERT GB700 1400 Tx DATA CLOCK EXT CLOCK INPUT CLOCK ...

Страница 75: ...l I Q QPSK Mod Demod I Q I Q Delay line or long coax cable GB700 1400 Tx DATA CLOCK DATA CLOCK Delay line can simulate a PRBS pattern with an offset of n clock bits Both I and Q channels running PRBS data but offset by n clocks GB700 1400 Rx data clock GB700 1400 Rx data clock I Channel BERT Q Channel BERT ...

Страница 76: ...Application Example 2 50 GB1400 User Manual ...

Страница 77: ...Reference ...

Страница 78: ... and Analyzer are both AC powered The power switch of both instruments is located on the front panel Selecting 115 VAC or 230 VAC Operation Both the GB1400Generator and Analyzer are equipped with an auto ranging AC power supply This supply will operate over a voltage range of 90 to 250 VAC and a frequency range of 47 to 63 Hz Thus no setup change is required to operate from 115 VAC at 60 Hz or 230...

Страница 79: ...ked LED on or unlocked LED off Simply press the PANEL LOCK control to toggle between the locked LED on and unlocked LED off state Selecting a Pattern The following section defines the patterns that can be generated and analyzed by the GB1400 and how to set up the Generator and Analyzer to use a particular pattern Note that the Generator and Analyzer are compatible with the same suite of test patte...

Страница 80: ...led you can create and save up to ten 64 kbit WORD patterns depends on buffer settings in battery backed memory Note that the standard and 1 Mbit instruments also store the current WORD pattern in battery backed memory Selecting the Active Pattern In this User s Guide the pattern currently being generated by the Generator or analyzed by the Analyzer is called the active pattern Procedures to make ...

Страница 81: ... available only in units equipped with the 1 Mbit Option Use the following procedure to select recall a WORD pattern Press the WORD key to place instrument in WORD mode Press the RECALL key Press the pattern up down keys until the desired WORD or desired mark density pattern is displayed Available selections will depend on the programmed WORD buffer size When set to ten 64k buffers available selec...

Страница 82: ...function used to load a user specified 8 bit pattern into all bytes and the ORDER function used to set the bit order in each byte to MSB or LSB first Thus you can use the Menu system to create long WORDs with simple bit patterns using its byte fill order and editing capabilities Downloading This is the best way to create long WORDs with complex patterns Long WORD patterns may be created on an exte...

Страница 83: ...rrent pattern will be displayed in the form AAAAA HH where AAAAA is the byte s location or address within the current WORD in decimal and HH is the value of the selected byte in hexadecimal Byte address will be in the range 0 1 8192 when BUFFER size is set to 64k or 0 1 16384 when BUFFER size is set to 128k 3 If you need to change WORD length press the WORD LENGTH key and then the pattern up down ...

Страница 84: ...r it is used to set the Analyzer pattern synchronization threshold in terms of BER A detailed explanation for each function in the WORD Menu may be found later in this chapter In addition the general procedure for creating WORD patterns in a Generator or Analyzer equipped with the 1 Mbit Option is given below 1 Use the current pattern or recall a previously saved pattern as the basis for the new p...

Страница 85: ... bytes Note that most WORD commands will function normally in instruments equipped with the 1 Mbit Option This allows instruments equipped with the 1 Mbit Option to operate in automated test applications designed around the 8 16 bit WORD command set However only byte commands may be used to edit long WORD patterns that is WORDs that are more than 16 bits long Therefore a GB1400 Generator or Analyz...

Страница 86: ...RD memory location Note that the WORD previously stored in this location will be overwritten 3 Press the SAVE key again to save the current WORD into the selected location At this point the SAVE LED will turn off Recalling Word Patterns 1 Mbit Memory Option To recall a previously saved WORD pattern use the following procedure 1 Press RECALL to enter the recall mode Note that the LED in the RECALL ...

Страница 87: ...or is set to internal clock mode any signal applied to this input will be ignored The EXTERNAL CLOCK input is AC coupled into 50 Ohms unless BURST OPTION is installed Clock Source Generator clock source may be set to internal or external using the EXT key in the CLOCK section When the LED in the EXT key is off then clock source is internal If the LED is on the clock source is external and an exter...

Страница 88: ...ck SAVE key Verify that the SAVE LED is flashing 2 Press the clock section up down keys to select the desired memory location Note that frequency memory location is displayed in the bottom left field of the display as FREQ x where x 0 1 9 3 Then press SAVE a second time to save the current frequency into this location Verify that the clock SAVE key LED turns off Recalling a Frequency You can recal...

Страница 89: ... CLOCK BAR are complementary outputs to DATA and CLOCK respectively Thus the GB1400 can drive single ended or differential inputs The amplitude and baseline offset of the CLOCK and DATA outputs are adjustable This insures compatibility with a wide range of input circuit designs The selected clock amplitude applies to both CLOCK and CLOCK BAR and the selected data amplitude applies to both DATA and...

Страница 90: ...A Same offset as DATA V top Same amplitude as DATA V top data V top clock Figure 3 1 Nominal Generator Clock and Data Waveforms Showing Amplitude Baseline Offset and Vtop Voch Out high voltage into an open circuit 50 Ω Ω 50 Ω Ω Vh logic high DATA or CLOCK Output Vhl logic low DATA or CLOCK Output Negative Supply l Vocamp 50 Figure 3 2 Generator Clock and Data Output Equivalent Circuits ...

Страница 91: ...amplitude p p Voffset 4 0 VDC RULE 3 Displayed amplitude and baseline offset are calibrated for a termination of 50 Ohms to ground Any variation of termination impedance or voltage will cause actual amplitude and offset to differ from the values shown in the Generator display These rules are summarized in the table below Table 3 2 Output Setup Rules vs Termination Impedance Termination Amplitude L...

Страница 92: ...own keys to set the desired data signal amplitude 4 Press CLOCK The display will now show clock output amplitude and offset 5 Press the BASELINE OFFSET up down keys to set the desired clock signal baseline offset 6 Then press the AMPLITUDE up down keys to set the desired clock signal amplitude Logically Inverting Output Data D INV The INVERT DATA key may be used to logically invert the output data...

Страница 93: ...r front panel contains two additional outputs that may be useful when observing the Generator output with an oscilloscope The first is the Pattern Sync or output which generates one pulse per pattern frame This signal may be used to trigger an oscilloscope at the beginning of the output data pattern The second is the CLOCK 4 output which is a clock signal at one quarter the frequency of CLOCK This...

Страница 94: ... Generator are RATE key SINGLE key When the LED on the RATE key is off the Generator is in the single error inject mode In this mode no errors are generated except when the SINGLE error key is pressed That is each press of the SINGLE key will cause a single isolated bit error to be injected However when the RATE key is on the instrument is either generating an error rate internally or under extern...

Страница 95: ...he single injection mode press RATE one or more times until ERR OFF is selected ERROR INJECT Input The ERROR INJECT input is an SMA female connector located on the rear panel of the Generator When the error injection mode is set to ERR EXT one bit error will be generated for each rising edge in the signal applied to this input Setup The ERROR INJECT is a 50 Ohm ECL input No hardware setup is requi...

Страница 96: ...on auto search will clear turn off the BIT and PHASE history indicators once pattern sync is regained Thus AUTO SEARCH can greatly simplify Analyzer setup and operation especially when the input clock and data phase relationship and amplitudes are not known DISABLE Key The DISABLE key is used to disable automatic pattern realignment When automatic pattern realignment is enabled DISABLE off the Ana...

Страница 97: ...o measure BER and count errors on on this combination not allowed AUTO SEARCH With PRBS Patterns When using a PRBS pattern you can enable the AUTO SEARCH feature as follows 1 Set up the Generator to transmit a PRBS pattern 2 Set up the Analyzer as follows EXT ref data input control off SYNC DISABLE off AUTO SEARCH on After you perform this procedure the auto search feature will be enabled and the ...

Страница 98: ... now start a new test interval by clearing previous results PRESS ERROR DETECTION CLEAR key and history indicators PRESS HISTORY CLEAR key How to DISABLE Automatic Pattern Resynchronization The pattern resynchronization disable feature is turned on or off as follows Press the DISABLE key to toggle automatic pattern resynchronization on or off When the DISABLE LED is on pattern resynchronization is...

Страница 99: ... levels available 1 3 1 E 02 2 7 8 E 03 3 1 9 E 04 4 9 7E 04 5 4 8 E 04 6 2 4 E 04 7 1 2 E 04 8 6 1 E 05 9 3 0 E 05 Use SYNC Menu to select a synchronization level from 1 to 9 You can change the synchronization threshold for long WORD mark density and ROM patterns using the SYNC Menu as follows Procedure to Set SYNC Threshold 1 Press the F1 key to enter the Menu system 2 Press F4 key to enter the ...

Страница 100: ...in the following figure 50 Ω Ω 2Vdc AC Input Comp GND Figure 3 3 Analyzer Clock and Data Input Circuits Input Parameters The following input parameters may be set manually by the user or automatically by the AUTO SEARCH function Decision threshold DATA and REF DATA Delay DATA and REF DATA Inverted or non inverted data DATA In addition there are termination parameters that can be selected only by t...

Страница 101: ...t input data inversion is enabled Specifically if the INVERT DATA key is on then the message INV will appear after the name of the current pattern for example PN 23 INV Input Data Delay Up to 4 ns of delay can be added to the DATA and REF DATA inputs to adjust their phase alignment with the input clock signal A different amount of delay may be added to each of these inputs so that the Analyzer can...

Страница 102: ...omes effective immediately In other words termination is changed each time you press the up or down key Low Frequency Effects of AC Termination on Single ended Operation Because the single ended AC termination is AC coupled to ground input impedance will deviate from the nominal 50 Ohm value at low frequencies As a practical matter for any PRBS pattern analyzed by the GB1400 frequency effects will...

Страница 103: ...isplay Decision threshold setup range is a function of input termination as shown in table below Table 3 8 Input Threshold Range as a Function of Termination Selected Termination Threshold Setup Range GND 1 5 to 1 0 VDC 50 mV steps 2 V 2 5 to 0 0 VDC 50 mV steps AC 1 5 to 1 0 VDC 50 mV steps The displayed threshold takes effect immediately In other WORDs threshold is incremented or decremented eac...

Страница 104: ...ications the Analyzer is set up to compare the received data pattern with a data pattern generated internally by the Analyzer However you may also set up the Analyzer to compare two externally generated patterns This makes it possible to analyze framed or proprietary signals that cannot easily be simulated as long WORD patterns To configure the Analyzer for reference data testing the primary or te...

Страница 105: ...o make specialized calculations MONITOR DATA is an NRZ output signal with the same bit sequence as that recovered by the Analyzer front end circuit MONITOR CLOCK is the corresponding clock signal Because the MONITOR output is a regenerated version of the received test signal bit errors reported by the Analyzer due to noise on the received data or clock signals will be present in the MONITOR DATA o...

Страница 106: ...ver long intervals Test results are used to measure error performance over specified time intervals Two results are calculated for all three methods BER Bit Errors In addition Test results include the following network performance parameters and event counts Test seconds Total bits monitored Errored seconds Severely errored seconds Unavailable seconds Threshold errored seconds Error free seconds D...

Страница 107: ...g window whose length is defined by the user Window results can be cleared at any time by pressing the CLEAR key when Window Mode results are displayed But as in the case of Totalize results the Window measurement process cannot be suspended by the user Window results may be thought of as a series of snapshots of the received signal performance Each snapshot indicates BER and total bit errors over...

Страница 108: ...t Process How TEST Results Are Measured Unlike Totalize and Window results the accumulation of Test results can be started or stopped by pressing the CLEAR key That is the CLEAR key in effect becomes a test start stop key While a test is stopped all current Test results are frozen When the CLEAR key is pressed to start a new test all current Test results are saved as previous Test results before c...

Страница 109: ...u Figure 3 6 The TEST Measurement Process Timed Tests When the Timed mode is selected the Analyzer will automatically stop accumulating Test results after the test interval specified by the user has elapsed All Test results will be frozen until the CLEAR key is pressed to begin a new test Repeat Timed Tests When the Repeat mode is selected the Analyzer will automatically stop and then restart a te...

Страница 110: ...aracter in front of the BER result as explained in the table below Note that there are three possible Test display mode characters T U and R which further indicate which Test timing mode Timed Untimed or Repeat has been set up Note that MODE is a parameter in the TEST Menu Table 3 9 How to Tell Which Display Mode is Active Character In Front of BER Result Indicated Result Display Mode no character...

Страница 111: ...ng on your MODE selection either the BITS or SECOND parameter In addition if you want to generate end of window reports you must also set the REPORT parameter to on Procedure 1 Press F1 to enter the Menu system 2 Select the WINDOW Menu F3 3 Within the WINDOW Menu set up a MODE F2 and b either BITS F3 or SECOND F4 4 Press MORE F1 to see the next page of the WINDOW Menu 5 If you are using a printer ...

Страница 112: ...nd if you are using a printer you should set the REPORT parameter as desired Note that On Error reports can generate a lot of paper so select On Error or Both with caution Setup of the other parameters in the TEST Menu are optional Procedure 1 Press F1 to access the Menu system 2 Select the TEST Menu F2 3 Within the TEST Menu set up a LENGTH F2 and b MODE F3 4 And if you are using a printer set up...

Страница 113: ...haracters indicate Test results which have been measured using the timed untimed or repeat timing modes respectively All Other Results Test Process only To view the complete set of Test results select the VIEW CUR or VIEW PRE functions from the TEST Menu VIEW CUR will show partial results if a timed test is in progress or results from the last completed test VIEW PRE will show results saved in the...

Страница 114: ...See Chapter 6 for details 2 Press F1 to enter the Menu system 3 Select MORE F1 to view the second page of the main Menu 4 Set up the appropriate hardware port as follows a If you are using a serial printer select RS232 F2 to set up the serial port b If you are printing to a GPIB controller select GPIB F3 to set up the GPIB port NOTE The Analyzer PRINTER port is a standard PC type parallel port whi...

Страница 115: ...OCK_TERM GND RDATA_TERM GND TEST_LENGTH 00 00 30 TEST_MODE TIMED TEST_PREV PRE TEST_REP ON_ERR TEST_STATE STOP TEST_SQUELCH OFF TEST_THRES OFF WIN_MODE SEC WIN_PREV CUR WIN_REP OFF WIN_BIT_LEN 09 WIN_SEC_LEN 00 00 01 PRINT_ENABLE ON PRINT_PORT PARALLEL AUDIO_VOL 0 AUDIO_RATE 3 PRBS_LENGTH 23 WORD_BITS 16 HAA H55 DATA_PATTERN WORD DATA_INVERT ON WORD_MEMORY 0 16 HAA H55 WORD_MEMORY 1 16 HAA H55 WOR...

Страница 116: ... 05 TIME ALARMS PERFORMANCE START Jun 14 99 02 43 26 SIG LOSS OS US 0 0 0 STOP Jun 14 99 0s 43 31 SYNC LOSS OS SES 0 0 0 ELAPSED 000 00 00 05 PHASE ERR OS TES 5 100 0 ES 5 100 0 ERRORS BITS EFS 0 0 0 TOTAL ERRS 000050000 AVG RATE 1 0E 04 DM 0 0 0 TOTAL BITS 500002816 CUR RATE 1 0E 04 You can set up the Analyzer to generate End of Test Reports as follows Procedure to Enable or Disable End of Test R...

Страница 117: ...gth T An example End of Window report is shown below Example End of Window Report Date Jun 14 99 Time 02 42 34 46 Bits 5 00E 08 Errs 5000 Err rate 1 0E 04 Freq 100 00 MHz Pattern AA55 Data los 0 Sync Los 0 Phase Err 0 Procedure to Enable or Disable End of Window Reports 1 Complete the Basic Report Setup Procedure 2 Press F1 to enter the Menu system 3 Select the WINDOW Menu F3 4 Press F1 to see the...

Страница 118: ...u may now either enable or disable End of Window reports by setting the WINDOW REPORT parameter to ON or OFF 6 Press F4 to lock in your selection 7 Press F1 multiple times to exit the Menu system On Demand Test Reports You can generate a test summary report on demand using the PRINT function in the TEST Menu While a test is in progress the PRINT function will generate a summary report based result...

Страница 119: ...iate Test Reports are identified as follows AVE RATE BER calculated over the entire TEST interval CUR RATE BER calculated over the latest WINDOW interval All Other Results Test Intervals Only The following results are calculated over Test intervals only You can view all Test results using the VIEW CUR and VIEW PRE functions in the TEST Menu Or you can print all Test results at the end of Test inte...

Страница 120: ...d seconds in the measurement interval TS total seconds in the measurement interval Error Free Seconds EFS The number of seconds that contain no errors and are not unavailable EFS TS ES US TS total seconds in the measurement interval ES errored seconds in the measurement interval US unavailable seconds in the measurement interval EFS Percentage Error free Seconds Error free seconds as a percentage ...

Страница 121: ...severely errored seconds SES and end upon the detection of 10 non severely errored seconds Percentage Unavailable Seconds US The number of unavailable seconds expressed as a percentage of total seconds in the measurement interval US US TS 100 US unavailable seconds in the measurement interval TS total seconds in the measurement interval Error History Indicators CLEAR SYNC LOSS BIT PHASE POWER The ...

Страница 122: ...r about seven seconds after the last key press Available selections are 1E x where x 2 3 16 2 Press the AUDIO VOL up or down keys to increment or decrement the current audio alert volume There are four volume levels The minimum value is OFF Except when volume is set to the minimum level a beep will occur each time you press an AUDIO VOL up or down key to indicate the current volume Analyzer Error ...

Страница 123: ...red In particular select a TEST timing mode Timed Untimed or Repeat 2 Use the DISPLAY SELECT key to set the display mode to TEST Verify that the expected TEST character T U or R is shown 3 If the TEST character is blinking press the ERROR DETECTION CLEAR key to stop the TEST process 3 At this point you may press the ERROR DETECTION CLEAR key to start a new TEST process at any time After pressing C...

Страница 124: ...is started and stopped manually Starting New Totalize and Window Measurement Intervals Unlike the TEST process the Totalize and Window measurement processes are continuous background processes that cannot be stopped and started by the user However you can clear all current results to start a new measurement interval as follows Procedure for Starting a New Totalize or Window Measurement Interval 1 ...

Страница 125: ...n also be performed using front panel keys for example setting WORD length However most Menu functions do not have front panel equivalents Menu and Function Pages Once you press the F1 key to enter the Menu system you will see two basic display or page formats Menus and functions Menu pages are used to pick a function or another Menu by pressing one of the function keys F1 F4 Function pages are us...

Страница 126: ...this example we will change TEST LENGTH from 1 hour as shown above to 30 minutes as shown below F1 ESC F2 F3 F4 SET TEST LENGTH 00 30 00 5 Note that there are two ways to exit a function like TEST LENGTH The normal way is to press F4 to lock in your changes and exit the function However you can also exit most functions without making any setup change by pressing F1 to escape In this example we ll ...

Страница 127: ...TS ON EOT ERROR 11 To lock in this change and return to the TEST Menu press F4 F1 F2 F3 F4 MORE LENGTH MODE REPORT 12 Since all of the setup goals have been accomplished we now want to exit the Analyzer Menu system To do this from the TEST Menu or from any Menu simply keep pressing the F1 key until the normal display appears In this example you would see the following a Press F1 and see the second...

Страница 128: ...te to a particular Menu function by pressing the appropriate F keys to select lower level Menus and finally the desired function 3 In multi field functions use the F2 move left or F3 move right keys to select a field Note that the selected field is indicated by its flashing mode flashing selected not flashing not selected 4 Once a field is selected use the pattern up down keys to increment or decr...

Страница 129: ...etailed description of each GB1400 Menu function Table 3 10 Menu Descriptions Menu Found In Which Instrument Description Main Analyzer and Generator Provides access to all other Menus Also contains a few functions not part of any other Menu TEST Analyzer only Contains functions to set up the TEST measurement process including timing mode End of Test reports and the test threshold WINDOW Analyzer o...

Страница 130: ... MORE MODE BITS SECOND 2 ESC to MAIN Menu REPORT WORD 1 MORE EDIT LENGTH FILL 2 ESC to MAIN Menu SYNC ORDER3 BUFFER RS232 1 MORE BAUD PARITY SIZE 2 ESC to MAIN Menu EOL XON XOFF ECHO PRINT 1 ESC to MAIN Menu PORT ON OFF UTIL 1 ESC to MAIN Menu OPTION VER NOTES 1 Menu names appear in bold typeface 2 Functions included only in instruments equipped with the 1 Mbit Option are marked with an asterisk 3...

Страница 131: ...TY SIZE 2 ESC to MAIN Menu EOL XON XOFF ECHO WORD 1 MORE EDIT LENGTH FILL 2 ESC to MAIN Menu ORDER3 BUFFER UTIL 1 ESC to MAIN Menu OPTION VER NOTES 1 Menu names appear in bold typeface 2 Functions included only in instruments equipped with the 1 Mbit Option are marked with an asterisk 3 The ORDER function appears under the F2 key in units not equipped with the 1 Mbit Option ...

Страница 132: ...zer Generator or both Which option s must be installed for this function to be available What this function is used for Parameters set using this function and their ranges Notes Note that most of the following function descriptions are identified by a Menu name and a function name for example Test Length This is to clarify the application of the described function and to differentiate functions th...

Страница 133: ...ecimal of the byte you want to edit in the current WORD May be set in the range 00001 to M 1 where M the number of whole bytes in the current WORD If WORD length is M bytes plus N bits then the byte location of the last N bits is M 1 Byte Value bbbbbbbb This is the binary representation of the selected byte Edit this byte using the front panel bit keys MSB 1 LSB 8 Range 00000000 to 11111111 binary...

Страница 134: ...the current WORD pattern Parameters Bytes mmmmm Set this parameter to the number of whole bytes in the pattern length That is if length is M bytes N bits set this parameter to M Range 0 to 16 384 Bits n Set this parameter to the number of extra bits in the pattern length That is if length is M bytes N bits set this parameter to N Range 0 to 7 Notes See an additional list of remote commands in the ...

Страница 135: ...on to fill all bytes in the current WORD with the same 8 bit pattern Parameters Fill Byte hh Enter the hex value for the fill byte Range 00 to FF Notes You may use the fill function as the basis for a new WORD pattern then edit individual bytes using the WORD EDIT function to create the exact pattern that you need See an additional list of remote commands in the Appendix that support the 1 Mbit Pr...

Страница 136: ...ication Use this function to change the transmit or analysis bit order MSB first or LSB first of the current WORD pattern Parameters Word Order ccc May be set to LSB or MSB Note Word order also applies to the fractional end byte in patterns that do not contain an exact multiple of eight bits See an additional list of remote commands in the Appendix that support the 1 Mbit Programmable Word option ...

Страница 137: ...xed Parameters Long Word Synchronization Threshold Level d Set this parameter to a level from 1 to 9 Notes The long WORD synchronization threshold is always set to 256 errors in a rolling window of variable length The length of this window is automatically set by the Analyzer based on the selected threshold level so that the nine threshold levels effectively correspond to the following bit error r...

Страница 138: ...àMORE à BUFFER Function Name BUFFER Instruments Generator and Analyzer Options 0 segments 1 Mbit 1 segment 512 kbits 3 segments 256 kbits 6 segments 128 kbits 10 segments 64kbits Application Selecting memory locations Parameters Ten possible WORD memory selections are WORD 0 thorugh WORD 9 Notes ...

Страница 139: ...ch it determines the threshold voltage setting delay data pattern and polarity BER This method requires the user to set criteria pertaining to Bit Error Rate threshold and sample size that is used to determine the size and center of the data eye Application Automatic setup and synchronization Parameters FAST BER Notes See the Auto Search Synchronization Application Note at the end of Chapter 2 ...

Страница 140: ...Options None required This is a standard feature Application Use this function to set the duration of timed tests and the repeat interval of repeat timed tests Parameters Hours hh Set from 00 to 23 Minutes mm Set from 00 to 59 Seconds ss Set from 00 to 59 Notes Test length does not affect untimed TEST intervals or the TOTALIZE or WINDOW measurement processes ...

Страница 141: ...nalyzer only Options None required This is a standard feature Application Use this function to select a test timing mode Parameters Test Timing Mode ccccccc May be set to TIMED REPEAT or UNTIMED Notes This function applies only to the TEST measurement process and has no impact on either the TOTALIZE or WINDOW measurement processes ...

Страница 142: ... feature Application Use this function to enable or disable End of Test and On Error reports Parameters Reports On ccccccccc May be set to NONE All test reports are disabled END OF TEST Only EOT reports enabled ON ERROR Only On Error reports enabled EOT ERROR Both EOT and On Error reports enabled Notes If you want to generate reports be sure the ON OFF function in the PRINT Menu is set to ON ...

Страница 143: ...nction Name THRES Instruments Analyzer only Options None required This is a standard feature Application Use this function to set the value of the test threshold Parameters Test Threshold eeeee Set from 1E 03 to 1E 16 Notes The test threshold affects On Error reports and the TES threshold errored second result ...

Страница 144: ...ion to enable or disable squelching of On Error reports Parameters On Error Squelch ccc Set to ON or OFF Notes When On Error Squelch is ON the analyzer will squelch temporarily stop printing On Error reports after ten consecutive reports that is ten consecutive seconds in which BER exceeds the current test threshold On Error reports will resume after 10 consecutive seconds in which the BER does no...

Страница 145: ...ation Use this function to print a test summary report based on current test results if a test is in progress or previous test results if a test is not in progress Parameters None This is an immediate function Simply press F4 to generate a report or F1 to escape the function without generating a report Notes Make sure the ON OFF function in the PRINT Menu is ON if you want to generate a test summa...

Страница 146: ...ough the results shown below START test start time STOP test stop time ELAPSED duration of test TTL BIT total number of bits in interval TTL ERR total number of bit errors counted AVE ERROR RATE BER of TEST interval CUR ERROR RATE BER of WINDOW interval US Unavailable Seconds SES Severely Errored Seconds TES Threshold Errored Seconds ES Errored Seconds EFS Error Free Seconds DM Degraded Minutes SI...

Страница 147: ... to view current test results In effect this function takes a snap shot of the latest results from a test in progress Parameters None This is an immediate function Use pattern up down keys to scroll through results Available results are the same as for VIEW PRE except that STOP time is replaced by the message TEST IN PROGRESS Notes If the TEST process is currently stopped this function will displa...

Страница 148: ...Name MODE Instruments Analyzer only Options None required This is a standard feature Application Use this function to set window length equal to the number of bits specified by the WINDOW BITS function or the time specified by the WINDOW SECOND function Parameters Window Mode ccccccc May be set to BITS or SECONDS ...

Страница 149: ...DOW LEN 1 0eEE BITS Menu WINDOW Function Name BITS Instruments Analyzer only Options None required This is a standard feature Application When WINDOW MODE is set to BITS use this function to set window duration in terms of bits Parameters Window Length EE May be set from 1 0e08 to 1 0e16 ...

Страница 150: ...WINDOW Function Name SECOND Instruments Analyzer only Options None required This is a standard feature Application When WINDOW MODE is set to SECONDS use this function to set window duration in terms of hours minutes and seconds Parameters Window Length hh mm ss hh Set from 00 to 23 mm Set from 00 to 59 ss Set from 00 to 59 ...

Страница 151: ...unction Name REPORT Instruments Analyzer only Options None required This is a standard feature Application Use this function to enable or disable End of Window reports Parameters End of Window Print ccc May be set to ON or OFF Notes To print End of Window reports be sure ON OFF parameter in PRINT Menu is set to ON ...

Страница 152: ...ET BAUD dddd Menu RS232 Function Name BAUD Instruments Analyzer and Generator Options None required This is a standard feature Application Use this function to set the baud rate of the serial RS 232C port Parameters Baud rate dddd May be set to 300 600 1200 2400 4800 or 9600 ...

Страница 153: ...t F1 ESC F4 SET PARITY cccc Menu RS 232 Function Name PARITY Instruments Analyzer and Generator Options None required This is a standard feature Application Use this function to set parity for the serial port Parameters Parity cccc May be set to ODD EVEN or NONE ...

Страница 154: ... SIZE d Menu RS232 Function Name SIZE Instruments Analyzer and Generator Options None required This is a standard feature Application Use this function to set the number of data bits per character for the RS 232 serial port Parameters Number of Data Bits d May be set to 7 or 8 ...

Страница 155: ...ments Analyzer and Generator Options None required This is a standard feature Application Use this function to select an end of line terminator This character or pair of characters will be added to the end of every line in reports sent to the RS 232 port Parameters End of Line Terminator ccccc May be set to CR LF LF CR CR or LF ...

Страница 156: ...XOFF ENABLE ccc Menu RS 232 Function Name XON XOFF Instruments Analyzer and Generator Options None required This is a standard feature Application Use this function to enable or disable Xon Xoff flow control Parameters Xon Xoff Flow Control ccc May be set to ON enabled or OFF disabled ...

Страница 157: ...lyzer and Generator Options None required This is a standard feature Application Use this function to enable or disable character echo on the RS 232 port When enabled the instrument will echo that is transmit back to the controller each character that it receives on the RS 232 port Parameters RS 232 Echo Enable ccc May be set to ON or OFF ...

Страница 158: ... Selected from main Menu Function Name GPIB Instruments Analyzer and Generator Options None required This is a standard feature Application Use to select the GPIB end of line termination character or characters Parameters GPIB End of Line Terminator cccccc May be set to EOI or EOI LF ...

Страница 159: ...tions listed here Menu UTIL Function Name OPTION Instruments Analyzer and Generator Options None required This is a standard feature Application Use this function to see which options are installed in your Analyzer or Generator Parameters None This is an immediate function ...

Страница 160: ... software version listed here Menu UTIL Function Name VER Instruments Analyzer and Generator Options None required This is a standard feature Application Use this function to see the software version installed in your unit Parameters None This is an immediate function ...

Страница 161: ...in Menu Function Name DATE Instruments Analyzer only Options None required This is a standard feature Application Use to set the Analyzer s internal date function Parameters Month mmm Set in range JAN FEB DEC Day dd Set in range 01 02 31 Year yy Set in range 93 99 Notes End of Test reports are date and time stamped ...

Страница 162: ...nu Function Name TIME Instruments Analyzer only Options None required This is a standard feature Application Use this function to set the instrument s 24 hour internal clock Parameters Hours hh Set in range 00 23 Minutes mm Set in range 00 59 Seconds ss Set in range 00 59 Notes The Analyzer clock uses a 24 hour format ...

Страница 163: ...Reference 3 86 GB1400 User Manual ...

Страница 164: ...Appendices ...

Страница 165: ... BAR NOT DATA GB1400 Generator TX Internal Clock Source Frequency Range 1 MHz to 1400 MHz Step Size Range 0 01 0 1 1 10 100 1000 MHz Resolution 1 kHz Accuracy 10 ppm within calibration interval Frequency Memory 10 frequencies External Clock Source Frequency Range 1 MHz to 1400 MHz Burst Mode Option 150 kHz to 1400 MHz Input Level 0 5V to 2 0Vp p Impedance 50 Ohm AC coupled with Burst Mode option 5...

Страница 166: ...lusive OR gate to the beginning of the shift register The feedback taps used in the GB1400 are tabulated here Pattern Feedback Taps PN7 6 7 PN15 14 15 PN17 14 17 PN20 17 20 PN23 18 23 Data Output True and Complement Amplitude Variable 0 5V to 2 0V 50 mV steps Baseline Offset Variable 2 0V to 1 0V 50 mV steps 2 0V to 1 8V 50 mV steps with PECL option Pulse Top Limit 2 0V into 50 Ohms 4 0V open load...

Страница 167: ...rs SMA Rear Panel Auxiliary Outputs Phase A Phase B Clock 2 Format NRZ L Level 250 mV p p into 50 Ohms 50 mV into Hi Clock Output 1 2 Clock Rate Phase A output Half rate data pattern Phase B output Half rate data pattern When in WORD mode Phase A and Phase B outputs are alternating bits Connectors SMA Error Injection Internal Rates Single or 1x10n for n 3 4 5 6 7 External 1 error injected for each...

Страница 168: ...emory unit operating frequency clock source status pattern select GPIB EOS character LF line feed OA hex GPIB Address Front panel select 0 30 or OFF BUS AC Power Requirements Voltage range 90 VAC to 250 VAC auto ranging Frequency range 47 63 Hz Power 125 VA Max Fuse rating 115 VAC 5 Amp SLO BLO 230 VAC 5 Amp SLO BLO Operating range 0 to 50 degrees C Mechanical Weight 10 Kg 22 lbs Size 152 mm H x 3...

Страница 169: ...threshold levels Connector SMA Burst Mode option 150 kHz to 1400 Mhz ECL Levels Data Input Format NRZ L True or inverted differential or single ended Data Rate 1 to 1400 Mb s Burst Mode option 150 kbps to 1400 Mbps Input Threshold 1 5V to 1 0V 50 mV steps Input Level 0 5V to 2 0Vp p Single ended operation requires external cable connection Impedance 50 Ohms Termination Voltage Selectable Gnd 2 0V ...

Страница 170: ...register outputs are selected For example PN7 is defined as a seven stage shift register which the output of stages 6 and 7 fed back through an exclusive OR gate to the beginning of the shift register The feedback taps used in the GB1400 are tabulated here Pattern Feedback Taps PN7 6 7 PN15 14 15 PN17 14 17 PN20 17 20 PN23 18 23 Reference Data Input Format NRZ L true Data Rate 1 Mb s to 1400 Mb s ...

Страница 171: ...g phase delay the input Data Pattern PRBS or WORD mode and Data Polarity There are two modes to find the Data Delay FAST A quick method using the Clock Data phase indicator BER A slower method which uses the signal s bit error rate Either method will make available the width of the Data Eye if possible The BER method allows user control over Data Sample Size 10E 4 to 10E 11 This is the number of d...

Страница 172: ...0E 5 256 8388608 Measurements BER Measurements Three simultaneous BER measurements Totalize Window and Test displayed as BER 9 9E 01 to 1 0E 16 Totalize 0 to 99999999 then 1 0E8 to 9 9E36 Totalize Mode BER since power on or reset Window Mode BER over sliding window programmable in time 1 sec to 24 24 hrs or bits 1E 8 1E 16 Test Mode BER over time of test programmable in time 1 sec to 24 hrs Additi...

Страница 173: ...allel Centronics type and re directable to serial RS 232C or GPIB ports Hardcopy Front panel key prints unit setup Print on event Print if BER threshold is exceeded programmable rate 1E 02 to 1E 16 Print on EOW Print on End of Window programmable in time 1 sec 24 hrs or bits 1E8 1E16 Print on EOT Print on End of Test programmable rate 1 sec to 24 hours AC Power Requirements Voltage range 90 VAC to...

Страница 174: ...Specifications A 10 GB1400 User Manual ...

Страница 175: ...ble of Contents BERT Primer see page B 2 Technical Articles BERT First and last measurement tool for transmission device design acceptability see page B 13 Ensure Accuracy of Bit Error Rate Tests see page B 21 Measure Error Rates Quickly and Accurately see page B 32 ...

Страница 176: ...vels BERT used to test physical layer To function at the physical layer BERTs must be capable of generating their own test patterns and of reporting bit errors versus expected data The fact that BERTs can operate at the most basic level of digital data transmission enables them to be very general purpose cutting across communications industry segments They are employed in the engineering developme...

Страница 177: ...eption of 0000000 Due to the nature of the Shift Register used to generate these codes the code 0000000 never appears Hence the PRBS pattern is always of the form 2n 1 e g 215 1 223 1 ITU Specifications CCITT O 150 and O 151 identify several types of PRBS patterns used for communications testing These patterns are usually generated by hardware shift registers with appropriate feedback If the shift...

Страница 178: ... and 11 2047 15 PN 15 215 1 x15 x 1 14 and 15 32 767 23 PN 23 223 1 x23 x5 1 18 and 23 8 388 607 31 PN 31 231 1 x31 x3 1 28 and 31 2 147 483 647 The Tektronix GB700 1400 provides capabilities to invert data on both transmit and receive This provides full flexibility to adjust the PRBS signal to the user s exact requirements Table B 2 identifies the GB700 1400 polynomial and shift register feedback...

Страница 179: ...the 1 because it would generate itself and no other combination Additionally the occasional 1 is required to keep a line alive so an all zero pattern beyond a specific bit length should never occur in real traffic Sample PRBS generators are shown below D Q1 D Q2 D Q3 CLK Output XOR Figure B 1 Three stage PRBS generator 2 3 1 PRBS Note Make sure shift registers are not initialized to logical 0 s th...

Страница 180: ... 0 0 3 0 0 1 0 1 4 1 0 0 1 1 5 1 1 0 0 0 6 0 1 1 0 1 7 1 0 1 1 0 8 0 1 0 1 1 9 1 0 1 0 1 10 1 1 0 1 1 11 1 1 1 0 1 12 1 1 1 1 0 13 0 1 1 1 0 14 0 0 1 1 0 15 0 0 0 1 1 Other Tx Patterns Other types of digital patterns may be sent by the generator Some of these are Mark Space Density groups of 1 s and 0s Custom Pattern entered into the BERT Tx Memory In some cases pattern data for error measurement ...

Страница 181: ...mit the availability of single ended or differential output The typical electrical I O on our BERTs is a 1 volt signal centered around ground either Differential or Single Ended Differential outputs provide an inverted copy of the output signal and are used to drive complimentary inputs If a single ended signal is needed the complimentary output should always be terminated to the appropriate load ...

Страница 182: ...evels Error Comparator The BERT receiver compares the incoming data stream bit by bit with its internal pattern using an Exclusive OR gate XOR and responds to non matching inputs by sending a 1 to a built in error counter The number of errors compared with the number of bits received determines the BER or Bit Error Rate This is usually expressed as a power of 10 using a negative exponent since the...

Страница 183: ...of 5 requires 400 errors to have been counted Conversely for 95 confidence that an error rate is less than some limit the DUT must be error free for three times the reciprocal of that limit For example to assure an error rate less than 10 per hour the test must run error free for 0 3 hours Additional Reading Dr Dan Wolaver has written an excellent article on confidence levels in BER measurements t...

Страница 184: ...ve to meet a spec such as eye width at 500Mb s and 10 9 BER must be 1 0ns or greater The manufacturer is then confident that there is sufficient margin in his product to live up to his customers expectations Vertical compression of the eye from ISI echoes regenerator output variations decision level instability etc from ideal can be used to extrapolate error rate and derive minimum S N ratios to a...

Страница 185: ...n This is the method the GB700 and GB1400 use for PRBS synchronization Both methods rely on realizing some minimum acceptable BER before the Receiver considers it has obtained pattern lock It will then begin accumulating bit errors in the error counter register Pattern Loading Software Almost all BERTs have the ability to accept loading of reference patterns into internal memories in both transmit...

Страница 186: ...User Manual Jitter Generation Some BERTs have the ability to generate and impose jitter on the internal clock A jittered External Clock input is the means for adding jitter to the Tx source on GB700 and GB1400 BERT instruments ...

Страница 187: ...re being hashed out When a protocol becomes firm and established the BERT is replaced by the Protocol Analyzer The Tektronix family of BERT products listed at the end of this article along with specific functionality all conform to the above description but differ from each other in frequency range number of channels and pattern and format generation capability Bit error rate testing A BERT s basi...

Страница 188: ...1 7 minutes 10 12 2 8 hours 1 2 days 10 15 116 days 3 17 years Testing until you have ten errors offers only a 68 confidence in the BER while 100 errors offers 90 confidence Think about how long it would take to obtain 90 confidence in systems running at 1 Mb s or 19 2 kilobaud if you were looking for a 10 9 BER So how do you get around taking 3 17 years to thoroughly test that 1 Gb s system with ...

Страница 189: ...oise close by However if a great many errors occur in a short period of time you may be able to correlate the burst of errors with other events either natural lightning around a microwave radio tower or man made running your test at precisely the same time as the once a month test of the back up diesel generator Jitter undesired variations in the timing of edge transitions in clock or data wavefor...

Страница 190: ... rounded and blend into each other making it difficult to tell where a pulse starts and stops The tails of data pulses interfere with following data and reduce the eye opening example shown in Figure 2 Superimposed pulses with jitter modulation Peak Peak Ideal pulse position Jitter modulation Figure 2 Example of a Eye Diagram as viewed on an oscilloscope Pulse rounding is due to phase dispersion c...

Страница 191: ...S will cycle endlessly through every combination of n bits except for the all zero state with no repeats until every combination has been generated see Figure 3 and Table 2 for the 24 1 PRBS A B C D XOR Figure 3 24 1 PRBS pseudorandom binary sequence generator Table 2 24 1 PRBS pattern Clock A B C D C XOR D 1 1 0 0 0 0 2 0 1 0 0 0 3 0 0 1 0 1 4 1 0 0 1 1 5 1 1 0 0 0 6 0 1 1 0 1 7 1 0 1 1 0 8 0 1 0...

Страница 192: ...sters with appropriate feedback If the shift register has n stages the maximum pattern length will be 2 n 1 If the digital signal is taken directly from the output of the shift register non inverted signal the longest string of consecutive ZEROs will equal n 1 If the signal is inverted n consecutive ZEROs will be produced The ITU Specification O 150 lists several different types of PRBS test patte...

Страница 193: ...allowing you to build test data that looks more like live traffic If you are testing an error correcting circuit on a modem the transmitted pattern could have parity errors that the modem should correct Because the receiver can reference different patterns independent of each other the expected pattern could reflect what the corrected data should look like with the errors fixed ...

Страница 194: ...BERT Technical Articles B 20 GB1400 User Manual ...

Страница 195: ...t be the first component to fail when the system is stressed Moreover a BERT s data pattern and clock quality typically differ from those of the system under test Consequently users must know how to obtain and understand these important specifications to ensure an accurate picture of their system s capabilities A digital transmission system see figure below includes a data source such as computer ...

Страница 196: ...ent can cause the recovered data to differ from the original data The primary job of a BERT is to determine the system s error rate rather than isolate the faulty component But for the sake of convenience the BERT may replace the clock source in the transmitter or receiver In this case some fault isolation may be possible by comparing the performance of the system clock sources with that of the BE...

Страница 197: ...smission the BERT receiver generates its own data pattern H which is the same as the desired data D The BERT receiver compares the received signal H with H and looks for errors The tester records the total number of errors the ratio of errors to bits the bit error rate the number of errored seconds ES and the ratio of ES to total seconds To make a valid comparison the BERT receiver must synchroniz...

Страница 198: ...tter The BERT transmitter s principal task is to send a data pattern to the transmission system The most general scheme is a repeating pattern that can be as short as 8 bits or as long as thousands of bits Users can design the pattern to exercise the system in a number of ways including noise margin and clock recovery stressing Noise Margin Stressing The quality of signal F determines whether the ...

Страница 199: ... This baseline wander reduces the noise margin Properly designed transmission systems ensure that data patterns have no frequency components below the coupling circuit s cutoff essentially eliminating baseline wander But a BERT can purposely introduce some baseline wander to measure the noise margin An example is an input signal D that starts with a 10001000 pattern and switches to a 11101110 patt...

Страница 200: ... example the pattern 11001100 won t change the DC content or noise margin By combining various amounts of this balanced pattern with the previous unbalanced patterns users can stress the system to varying degrees up to 50 see table below Table 1 Data patterns for noise margin stressing Pattern A Pattern B Margin reduction 1100110011001100 1100110011001100 0 1000110011001100 1110110011001100 12 5 1...

Страница 201: ... and the rest are data bits A BERT transmitter can generate such a pattern to test terminal equipment that looks for the framing and control bits Fixed data patterns are stored in the BERT transmitter User defined patterns are stored in RAM and manufacturer provided patterns are stored in ROM The BERT receiver must be programmed to produce the same data pattern as the transmitter The receiver sync...

Страница 202: ...n will stress the clock recovery circuit if the pattern s fundamental is within the B If it is the pattern introduces random fitter in the recovered clock The jitter s magnitude depends on fB and on offsets within the circuit The rms jitter is not a function of the PRBS pattern length but the peak jitter increases with pattern length Examining Jitter An important factor in a data transmission syst...

Страница 203: ...density of the clock source phase jitter Φθi f and the clock recovery bandwidth fB are known the rms phase error can be calculated θerms π 2 fBΦθi fB Equation 1 BERT manufacturers sometimes specify the clock s single sideband noise density Φvi f at an offset frequency of 10 kHz which is also the value of Φvi 10 kHz From this figure the value of Fqi fB can be approximated by Fqi fB 10 kHz fB 2 Fqi ...

Страница 204: ... recovery circuit may fail to maintain lock if θe is too great In any case θe max is generally between 0 3 and 1 0 UI peak to peak If the system s θe max is unknown it can be measured The transfer function from θi to θe is θe θi fm f2 m f2 B 1 2 Equation 2 where fm is the frequency of the sinusoidal jitter Then the maximum data jitter a receiver can tolerate is θi max θe max θe θi Below fB θI max ...

Страница 205: ...ill have a higher error rate or less margin than when the system s clock source is used Measuring the clock source spectral density and calculation θe rms will uncover this problem Another snag may be that a BERT receiver has a very narrowband clock recovery circuit such as crystal controlled phase locked loop The small fB will probably make the BERT less tolerant of jitter than the system its tes...

Страница 206: ...cation systems are required to have very low error rates on the order of 1 error in a billion bits or a bit error ratio BER of 10 9 or less When you must measure such low error rates you are faced with a tradeoff either the test will take a long time or the results will not be accurate An example will illustrate a typical situation with such a tradeoff Suppose the communication system under test h...

Страница 207: ...e test have to take upwards of ten hours BER Measurement Inaccuracy versus Test Time The example above raises questions of how close a measured error rate is to the actual error rate and how long it takes to get there We can get quantitative answers if we make some assumptions about the process producing the errors Errors produced by noise are usually a Poisson process see the sidebar on Poisson E...

Страница 208: ...collect 100 errors turned out to be T 19 hr then r 100 19 hr 5 26 hr and this is within 10 of the actual error rate r That is r is inferred to lie between 5 26 0 526 4 734 hr and 5 26 0 526 5 78 hr with a confidence of 68 Because of the statistical nature of the measurement n 100 can be more than 10 away from the expected measurement but 68 of the time it will be less than 10 away You can increase...

Страница 209: ...s gives the probability of measuring n 0 as p 0 e rT 8 Then set p 0 0 10 or 10 and solve for T T r r ln 0 10 2 3 9 For r 5 56 hr this gives T 0 414 hr If the system is error free for 0 414 hour 25 minutes you are 90 confident that the error rate is less than r 5 56 hr In general for a confidence level C that the error rate is less than r the error free period is given by T C r ln 1 10 For example ...

Страница 210: ...tted here as a function of the signal to noise ratio SNR where SNR is S Nrms in decibels electrical S is the distance from the signal 1 or 0 to the decision threshold and Nrms is the rms value of the Gaussian noise introduced by the first receiver state a In b the log scale was distorted so the plot is a straight line The stress that we propose is attenuation of the received signal S Most of the s...

Страница 211: ...3 2 1 0 Figure 5 BER is plotted as function of electrical signal attenuation for the case of a system with BER 10 6 for no attenuation That is the SNR0 for no attenuation is 18 dB Then SNR with attenuation is 18 dB minus attenuation and BER follows from Figure 4 It isn t practical to plot a curve such as that in Figure 5 it would take too long to plot the points for low BER But if the noise is kno...

Страница 212: ...is reduced to 3 dB and 16 100 errors are measured in 60 seconds This is a BER of 16100 60 1544000 6 10 6 which is also plotted in Figure 6 A straight line through the two points intersects the BER axis at 10 10 so the unstressed BER would be 10 10 one error every 3 7 minutes on average 10 16 10 14 10 12 10 10 10 9 10 8 10 7 10 6 10 5 BER Attenuation dB 10 3 10 4 7 6 5 4 3 2 1 0 Example 1 Example 2...

Страница 213: ...is uncertainty is indicated by plotting a bar at 6 dB in Figure 6 Then the electrical attenuation is reduced to 4 dB and 37 errors are measured in 60 seconds This is a BER of 37 60 1544000 4 10 7 But with 37 errors the inaccuracy is 16 and the BER lies between 3 35 10 7 and 4 65 10 7 This is also plotted as a bar in Figure 6 Straight lines passing through the two bars sweep out the gray region sho...

Страница 214: ...enuation at this point is 3 dB In the fourth example in the text 1 dB of optical attenuation is needed to turn a test for BER 10 10 with no stress into a test for BER 2 x 10 7 with stress In this case stressing has reduced the test time by a factor of 10 000 This is probably more reduction than is needed It would be better to stress the system less so the test conditions are not so greatly differe...

Страница 215: ...cy can be improved only by taking more time to do the measurement A good rule of thumb is that the inaccuracy is the reciprocal of the square root of the number of errors counted For example the inaccuracy is 5 if 400 errors are counted Determining that an error rate is below some limit takes less time than determining the error rate accurately If the system under test is error free of a period T ...

Страница 216: ...for the same r and T the standard deviation of the measurement n is given by σ µ rT see Papoulis for a proof of this In this case σ 5 2 24 which is 45 of µ see Figure S 1b 0 1 2 3 4 5 6 7 8 9 10 11 12 13 0 0 02 0 04 0 06 0 08 0 1 0 12 0 14 0 16 0 18 p n n µ σ σ σ 0 45µ S 1a 0 10 20 30 40 50 60 70 80 90 100 110 120 130 0 0 01 0 02 0 03 0 04 0 05 0 06 p n n σ µ 0 14 σ µ σ S 1b Figure S 1a Probabilit...

Страница 217: ...n practice it would take an infinite time to measure r The standard deviation of the error measurement n is σ µ rT But since µ and r can t be known exactly in practice we must use the estimates µ n and r r to get the estimate σ n r T 10 16 10 14 10 12 10 10 10 9 10 8 10 7 10 6 10 5 BER Attenuation dB 10 2 10 3 10 4 11 10 9 8 7 6 5 4 3 2 1 0 0 0 5 1 1 5 2 2 5 3 3 5 4 4 5 5 5 5 elec opt Figure S 2 S...

Страница 218: ...rch and development at Tektronix BTT Inc He received a PhD in electrical engineering from MIT in 1969 For ten years he worked for Bell Labs on digital communications systems and he taught at Worcester Polytechnic Institute for eleven years He is the author of Phase Locked Loop Circuit Design ...

Страница 219: ...both alphabetical and functional order Type of Commands Starts on page IEEE 488 12 Pattern and Word 19 GPIB and RS 232 26 Shared Commands 30 Clock Source and Frequency Setup 33 Output Clock and Data Setup 37 Error Injection 43 Results Retrieve 44 Input Setup 54 Error Detector and History Setup 64 Test Setup 71 Window Setup 77 Print Setup 81 Audio Beeper Setup 83 Date Time 86 Commands specific to 1...

Страница 220: ...a message terminator signal specified in ANSI IEEE Std 488 2 1987 ui Unsigned integer in range 0 through 65 535 NR1 Signed integer value NR2 Floating point value without an exponent NR3 Floating point value with an exponent non decimal numeric A non decimal integer in the range 0 255 decimal with leading H hexadecimal Q octal or B binary Examples Hexadecimal HFF Octal Q377 Binary B11111111 qstring...

Страница 221: ...o as simply commands Command Line Format Command Names Headers Every GB1400 command starts with a command header Headers are character strings that contain either an entire command name or a legal abbreviation of a command name Legal command name abbreviations must include the leading significant characters in the command name For example in the save_word command only the first two letters are sig...

Страница 222: ...of Characters per Line Command lines may contain a maximum of 80 characters before the terminator Command Headers Names Each command must start with a header This header must contain either the full name of the command or an abbreviation containing at least all of the leading significant characters identified for that command name In addition query commands must end with a Upper and Lower Case All...

Страница 223: ...the instrument will reject the command Numeric Responses If the response to a query command is a number then it will be specified as one of the following types Type Description NR1 decimal integer e g 8 NR2 decimal real number without exponent e g 2 00 NR3 decimal real number with exponent e g 700 0E 6 Non decimal numeric non decimal number with leading H hexadecimal Q octal or B binary ...

Страница 224: ... 16 Haa H23 Sets the 16 bits of the word pattern stored at location 9 to the bit sequence represented by AA23 hexadecimal word_bits 8 Q307 Sets the first eight bits of the current active pattern to the bit sequence represented by 307 octal recall_word 7 Recalls the word pattern saved in location 7 and makes it the current active pattern word_mem_len 6 16 Sets the length of the word pattern stored ...

Страница 225: ... C 16 tst C 17 wai C 17 all_mem C 30 amplitude v C 37 amplitude C 37 audio_rat_dn C 83 audio_rat_up C 83 audio_rate v C 83 audio_rate C 84 audio_vol v C 84 audio_vol C 84 audio_vol_dn C 85 audio_vol_up C 86 auto_mode C 64 auto_sample n C 65 auto_search auto off disab C 63 auto_search C 63 auto_thresh n C 66 auto_width C 66 byte_block a i b1 bn C 89 byte_block a C 90 byte_delete a i C 91 byte_edit ...

Страница 226: ...39 clock_source int ext C 34 clock_source C 34 clock_step v C 35 clock_step C 35 clock_stp_dn C 35 clock_stp_up C 35 clock_term neg_2v gnd ac pos_3v C 54 clock_term C 54 data_amp_dn C 39 data_amp_up C 39 data_ampl v C 40 data_ampl C 40 data_del_dn C 55 data_del_up C 55 data_delay v C 56 data_delay C 56 data_invert on off C 19 data_invert C 19 data_off_dn C 40 data_off_up C 40 data_offset v C 41 da...

Страница 227: ...der C 31 histry_bits C 68 histry_clear C 68 histry_phase C 69 histry_power C 69 histry_stat C 69 histry_sync C 70 logo C 31 offset v C 42 offset C 42 options C 32 prbs_length v C 20 prbs_length C 20 print_enable on off C 81 print_enable C 81 print_port parallel gpib serial C 81 print_port C 82 print_string s C 82 rdata_del_dn C 59 rdata_del_up C 59 rdata_delay v C 60 rdata_delay C 60 rdata_term ne...

Страница 228: ...res_tot_rate C 51 res_us C 52 res_us_per C 52 rs_echo on off C 27 rs_echo C 27 rs_pmt_lf on off C 27 rs_pmt_lf C 28 rs_prompt s C 28 rs_xon_xoff on off C 28 rs_xon_xoff C 29 save_freq m C 36 save_word m C 21 sync C 70 test_discard C 71 test_length t C 71 test_length C 71 test_mode untimed timed repeat C 72 test_mode C 72 test_prev current previous C 72 test_prev C 73 test_print C 73 test_report eo...

Страница 229: ...it_len C 77 win_bits C 77 win_error C 77 win_mode bits sec C 78 win_mode C 78 win_prev current previous C 78 win_prev C 78 win_rate C 79 win_report on off C 79 win_report C 79 win_sec_len s C 80 win_sec_len C 80 win_time C 80 word_bits l b1 b2 C 21 word_bits C 22 word_length l C 22 word_mem_len m l C 22 word_mem_ord m msb lsb C 23 word_mem_ord C 23 word_mem_ord m C 23 word_memory m l b1 b2 C 24 wo...

Страница 230: ...the data threshold set and query commands above will be listed under the name DATA_THRES Common and Proprietary GPIB Commands The following GPIB common commands defined in ANSI IEEE Std 488 2 1987 cls Clear Status This set command clears the Standard Event Status Register SESR and the event status bit ESB in the Status Byte Register SBR In addition it puts the instrument into the Operation Complet...

Страница 231: ...55 corresponding to the contents of the Standard Event Status Register SESR Min Abbr esr Returns NR1 where NR1 is a decimal number in the range 0 to 255 Example esr command 213 response idn Identify Query Returns the GB1400 Generator or Analyzer identification including company name BERT model number Generator or Analyzer identifier and software version number Min Abbr idn Returns TEKTRONIX BERT 1...

Страница 232: ... AUTO BYTE_LENGTH 8 0 WIN_SEC_LEN 00 00 1 WORD_ORDER MSB opc Operation Complete This command will cause the OPC bit in the Standard Event Status Register to be set to one If the OPC bit is enabled this will result in an SRQ Thus the opc command can be issued after a group of setup commands to determine when all of the setup commands have been executed Min Abbr opc Example opc opc Operation Complet...

Страница 233: ...ry default settings Appendix B However rst does not impact any of the following q the setup of the RS 232 or GPIB ports q GPIB address q calibration data q the Standard Event Status Register SESR q the Event Status Enable Register ESER q the power on status clear flag setting q stored frequencies or words Min Abbr rst Example rst sre n Service Request Enable This command sets the Service Request E...

Страница 234: ...a decimal number in the range 0 to 255 where Bit 6 is ignored Example sre command 32 response Indicates that the SRE contains 00100000 binary stb Status Byte Query Returns a decimal number in the range 0 to 255 corresponding to the contents of the Status Byte Register SBR where bit 6 is the Master Summary Status bit Min Abbr stb Returns NR1 where NR1 is a decimal number in the range 0 to 255 where...

Страница 235: ...top processing any additional commands until all pending operations are completed Min Abbr wai tse v Analyzer Only Test Status Enable This command sets the Test Status Enable Register to the bit sequence corresponding to v where v is a decimal number in the range 0 to 255 Min Abbr tse Argument n NR1 in the range 0 to 255 Example tse 255 sets the TSR to 11111111 binary tse Analyzer Only Test Status...

Страница 236: ...nual tsr Analyzer Only Test Status Register Query This command returns a decimal number representing the current contents of the Test Status Register TSR Min Abbr tsr Returns NR1 in the range 0 to 255 Example tsr command TSR 224 response ...

Страница 237: ... or the Analyzer input bit sequence Min Abbr data_inv Arguments on enables data inversion outputs inverted data off disables data inversion outputs true data Example data_invert off data_invert Data Inversion Query Returns a character string indicating whether Generator output data inversion or Analyzer input data inversion is enabled on or disabled off Min Abbr data_inv Returns on off Example dat...

Страница 238: ...attern command The argument v may be set to 7 15 17 20 or 23 corresponding to the five PRBS patterns that can be transmitted by the Generator and Analyzed by the Analyzer Min Abbr prb Arguments 7 Selects the PRBS with a length of 27 1 bits 15 Selects the PRBS with a length of 215 1 bits 17 Selects the PRBS with a length of 217 1 bits 20 Selects the PRBS with a length of 220 1 bits 23 Selects the P...

Страница 239: ...attern to word memory location m Min Abbr save_w Arguments m 0 1 9 Example save_word 5 word_bits l b1 b2 Word Bits Returns the programmable WORD pattern The response will contain the pattern length and data bytes Sets current word length to l bits and sets the current word pattern to the bit sequence represented by b1 and b2 Min Abbr word_b Arguments l 8 or 16 b1 00 to FF hexadecimal Q000 to Q377 ...

Страница 240: ...length is 16 bits and the current pattern is AAF0 hex word_length l Word Length Sets the current word pattern length to 8 or 16 bits Min Abbr word_l Argument l 8 or 16 Example word_length 16 NOTE There is no query form to the word_length command However you may use the word_bits query to read the current word length word_mem_len m l Word Memory Length Sets the length of the word pattern saved in l...

Страница 241: ...cating the bit order of each of the 10 word memory locations The response will consist of 10 message units separated by semi colons and will contain the memory location and word order of each memory Min Abbr word_mem_o Returns NR1 MSB LSB NR1 MSB LSB etc Example word_mem_ord command WORD_MEM_ORD 0 LSB response WORD_MEM_ORD 1 MSB WORD_MEM_ORD 2 MSB word_mem_ord m Word Memory Order Query Returns a c...

Страница 242: ...ord memory 3 word_memory m Word Memory Query Returns the 8 or 16 bit pattern saved in word memory m in the form m byte 1 byte 2 where m is either 8 or 16 word length in bits and byte 1 and byte 2 are hex representations of the first and second bytes in the pattern Note that byte 2 will be included only if pattern length is 16 word_memory returns the contents of all programmable WORD memories The r...

Страница 243: ...r the change If the ORDER is changed in the middle of programming pattern bytes the bytes programmed prior to the ORDER change will be reversed from those programmed after the change For example if the WORD ORDER was previously LSB in memory 6 and the data pattern is programmed as follows edit_begin 6 byte_length 4 0 byte_block 0 16 HAA HAA word_order MSB byte_block 2 16 HAA HAA edit_end 6 The pat...

Страница 244: ... WORD ORDER as that associated with the pattern memory location being used the WORD ORDER must be specified prior to any editing or downloading Example 3 To select 512K word mode and have a particular stored pattern with different current pattern byte_mode 512 edit_begin 1 word_order msb byte_length 65536 0 byte_fill 48 H00 H22 H44 H66 H88 HAA edit_end 1 save_word 0 edit_begin 1 word_order lsb byt...

Страница 245: ...he chart above can be used to determine which stored patterns will be saved after a MODE transition and in which storage location it will be found For example on transitions from 128K to 256K the stored patterns 0 2 and 4 of the 128K mode will be found at the 256K locations 0 1 and 2 respectively while the stored patterns at 1 3 and 5 of the 128K will be lost On switching to a smaller MODE only wh...

Страница 246: ... Memory Query Returns the all ten programmable WORD memories The response will be ten message units separated by semi colons and each will contain the memory location length and data bytes of each memory Response NR1 Numeric NR2 Numeric non decimal numeric s ...

Страница 247: ...l number indicating the instrument s GPIB address It may only be issued over the RS 232C port Min Abbr gpib_a Returns NR1 Example gpib_address command GPIB_ADDRESS 15 response gpib_bus off_bus talk_listen GPIB Bus Mode This command sets the instrument s gpib bus mode It may be used only over the RS 232C port Min Abbr gpib_b Arguments off_bus puts instrument in the gpib off bus mode In this mode it...

Страница 248: ...t will echo back each character received off Disables ECHO mode instrument will not echo received characters Example rs_echo on rs_echo RS 232C Echo Query Returns a character string indicating whether RS 232C port echo is enabled ON or disabled OFF Min Abbr rs_e Returns on off Example rs_echo command RS_ECHO OFF response rs_pmt_lf on off RS 232C Prompt Line Feed This command may be used to add the...

Страница 249: ... port to the character string contained in the quoted string s This string will appear at the start of each new line on a terminal display Maximum length is 8 characters Min Abbr rs_pr Arguments s qstring a character string inside double quotes Example rs_prompt GB 1400 command will change the prompt to GB1400 þ NOTE This command may be issued with a null string argument to disable the RS 232C pro...

Страница 250: ...nual rs_xon_xoff RS 232C Xon Xoff Query This command returns a character string indicating whether RS 232C port Xon Xoff flow control is enabled or disabled Min Abbr rs_x Returns on off Example rs_xon_xoff command RS_XON_XOFF ON response ...

Страница 251: ...ries Min Abbr all_ Returns string NR1 NR3 NR1 NR1 Non decimal numerics Example all_mem command CLOCK_SOURCE INT response CLOCK_MEMORY 0 500 000E 6 CLOCK_MEMORY 1 550 000E 6 CLOCK_MEM 9 700 000E 6 WORD_MEMORY 0 16 HAA HBB WORD_MEMORY 1 8 HF0 WORD_MEMORY 9 16 HFF H00 All Memory Analyzer Returns the contents of all 10 Analyzer word memories Returns NR1 NR1 Non decimal numerics Example all_mem command...

Страница 252: ...command HEADER ON response logo Logo Query Returns a character string showing the Generator or Analyzer logo including company name BERT model number Generator or Analyzer identifier and software version number This command may be used only on the RS 232C port Use the idn query to get this same information over the GPIB port Min Abbr l Returns TEKTRONIX BERT 1400 RX TX Vs ss mm yy where RX indicat...

Страница 253: ...Option installed BURST Indicates BURST Mode installed PECL Indicates PECL Mode installed NONE Indicates no options are installed Examples options command OPTIONS NONE response options command OPTIONS 1 MB PROM 75 OHM response BURST PECL options command OPTIONS 1 MB response view_angle v View Angle This command sets the LCD display viewing angle to v Min Abbr v Arguments v NR1 may equal 0 lowest 1 ...

Страница 254: ...ck_f Arguments v NR3 in the range 1 000E 6 to 1405 000E 6 in steps of 0 001E 6 Example clock_freq 622 000E 6 clock_freq Clock Frequency Query Returns the current Generator clock frequency setting Min Abbr clock_f Returns NR3 Example clock_freq command CLOCK_FREQ 0 150E 6 response clock_memory Clock Memory Query Returns the contents of all ten frequency memory locations The response will be 10 mess...

Страница 255: ...ory location m The response will contain the memory location and the frequency Min Abbr clock_m Returns m NR1 NR3 in the range 0 9 Example clock_memory 4 command CLOCK_MEMORY 4 100 000E 6 response clock_source int ext Clock Source Sets the clock mode of the Generator to either internal int or external ext Min Abbr clock_so Arguments int Selects the internal clock source ext Selects the external cl...

Страница 256: ... 000E 6 response clock_stp_up and clock_stp_dn Clock Step Up Clock Step Down This command pair is used to increment or decrement the current Generator frequency using the step size previously defined with the clock_step command Min Abbr clock_stp_u clock_stp_d Arguments none Example clock_step_up clock_step_dn clock_stp_up v and clock_stp_dn v Clock Step Up Clock Step Down This command pair is use...

Страница 257: ... The recalled frequency becomes the current frequency of the Generator internal clock Min Abbr recall_f Arguments m NR1 in the range 0 1 9 Example recall_freq 5 save_freq m Save Frequency This command saves the current Generator internal clock frequency to memory location m Min Abbr save_f Arguments m NR1 in the range 0 1 9 Example save_freq 8 ...

Страница 258: ...eturns two message units the first indicating the clock amplitude setting and the second indicating the data amplitude setting Min Abbr am Returns NR2 NR2 Example amplitude command CLOCK_AMPL 1 450 DATA_AMPL 1 450 response clock_amp_up and clock_amp_dn Clock Amplitude Up Down Default This command pair is used to increment or decrement the current clock amplitude setting by the default increment of...

Страница 259: ...is command sets the output clock amplitude to v volts Min Abbr clock_ampl Arguments v NR2 in the range 0 50 to 2 00 in steps of 0 05 Example clock_amplitude 2 00 clock_ampl Clock Amplitude Query Returns the current output clock amplitude setting Min Abbr clock_ampl Response NR2 Example clock_ampl command CLOCK_AMPL 1 40 clock_off_up and clock_off_dn Clock Offset Up Clock Offset Down Default This c...

Страница 260: ...ck_off_dn 0 10 clock_offset v Clock Offset Sets the baseline offset of the output clock signal to v volts Min Abbr clock_offs Arguments v NR2 in the range 2 00 to 1 00 in steps of 0 05 in the range 2 00 to 1 80 in 0 05 v steps PECL option Example clock_offset 0 75 clock_offset Clock Offset Query Returns the current value of the output clock signal baseline offset Min Abbr clock_offs Returns NR2 Ex...

Страница 261: ... Example data_amp_up 1 00 data_ampl v Data Amplitude Sets the amplitude of the Generator s data output signal to v volts Min Abbr data_ampl Arguments v NR2 in the range 0 50 to 2 00 in steps of 0 05 Example data_ampl 1 00 data_ampl Data Amplitude Query Returns the current amplitude setup of the Generator s data output signal Min Abbr data_ampl Returns NR2 Example data_ampl command DATA_AMPL 1 00 r...

Страница 262: ... 0 05 to 3 00 in steps of 0 05 in the range 0 05 to 3 80 in 0 05 v steps PECL option Example data_off_up 0 20 data_offset v Data Offset Sets the baseline offset of the Generator data output to a specified value of v volts Min Abbr data_offs Arguments v NR2 in the range 2 00 to 1 00 in steps of 0 05 in the range 2 00 to 1 80 in 0 05 v steps PECL option Example data_offset 0 50 data_offset Data Offs...

Страница 263: ... the range 2 00 to 1 00 in steps of 0 05 in the range 2 00 to 1 80 in 0 05 v steps PECL option Example offset 1 50 offset Offset Query Returns two message units the first containing the Generator clock output baseline offset and the second containing the Generator data output baseline offset Min Abbr off Returns NR2 NR2 Example offset command CLOCK_OFFSET 1 500 response DATA_OFFSET 1 500 ...

Страница 264: ... 10 3 rate_4 sets bit error injection rate to 10 4 rate_5 sets bit error injection rate to 10 5 rate_6 sets bit error injection rate to 10 6 rate_7 sets bit error injection rate to 10 7 Example error_rate rate_6 error_rate Error Rate Query Returns a character string indicating the current Generator output error injection mode and rate Min Abbr error_r Returns off ext rate_3 rate_4 rate_5 rate_6 ra...

Страница 265: ...l place and a signed exponent following the letter E Examples 1 00E 9 9 99E 7 2 08E 14 þ NOTE Returning Current or Previous Test Results In response to queries for test interval results the Analyzer will return results from the current interval so far or from the previous interval based on the following rules 1 If the TEST PREV has been set to CURRENT and a test is in progress then the instrument ...

Страница 266: ... current interval so far or the previous test interval depending on the setup of TEST PREV and the current test state Min Abbr res_b Returns NR1 Example res_bits command RES BITS 4230452921 response res_cur_rate Results Current Rate Query This command returns the BER measured either in the most recent second of the current test interval or the last second of the previous test interval depending on...

Страница 267: ...ommand returns the percentage of degraded minutes calculated either in the current test interval so far or in the previous test interval depending on the setup of TEST PREV and the current test state Min Abbr res_dm_ Returns NR2 Example res_dm_per command RES_DM_PER 20 20 response res_efs Results Error Free Seconds This command returns the number of error free seconds counted either in the current...

Страница 268: ... string indicating the time elapsed either in the current interval so far or the previous interval depending on the setup of TEST PREV and the current test state Min Abbr res_el Returns qstring in format ddd hh mm ss where ddd days hh hours mm minutes and ss seconds Example res_elapsed command RES_ELAPSED 000 23 52 30 response res_errors Results Errors This command returns the total number of bit ...

Страница 269: ...urns the percentage of errored seconds calculated either in the current test interval so far or in the previous test interval depending on the setup of TEST PREV and the current test state Min Abbr res_es_ Returns NR2 Example res_es_per command RES_ES_PER 89 35 response res_los Results Loss of Signal Seconds This command returns the total number of seconds counted that contained a loss of signal e...

Страница 270: ...turns the total number of severely errored seconds counted either in the current test interval so far or in the previous test interval depending on the setup of TEST PREV and the current test state Min Abbr res_ses Returns NR1 Example res_ses command RES_SES 1290121 response res_ses_per Results Severely Errored Seconds Percentage This command returns the percentage of severely errored seconds coun...

Страница 271: ...est interval This command will produce a return if and only if previous results are available Previous results become available after TEST STATE has made at least one RUN to STOP transition Min Abbr res_sto Returns qstring qstring in the format yy mm dd hh mm ss th where yy year mmm month JAN FEB DEC dd day hh hours mm minutes ss seconds th tenths and hundreds of seconds Example res_stop command R...

Страница 272: ...Percentage This command returns the percentage of threshold errored seconds either in the current test interval so far or in the previous test interval depending on the setup of TEST PREV and the current test state Min Abbr res_tes_ Returns NR2 Example res_tes_per command RES_TES_PER 5 52 response res_tot_rate Results Total Bit Error Rate This command returns the totalized error rate of the entire...

Страница 273: ...and returns the percentage of unavailable seconds either in the current test interval so far or in the previous test interval depending on the setup of TEST PREV and the current test state Min Abbr res_us_ Returns NR2 Example res_us_per command RES_US_PER 29 01 response total_bits Totalize Bits Query Returns the total number of bits accumulated in the current Totalize measurement interval The Tota...

Страница 274: ...Totalize measurement interval Totalize BER equals the Totalize bit error count divided by the Totalize bit count The number will reset at power up and on error reset Min Abbr total_r Returns NR3 Example total_rate command TOTAL_RATE 8 62E 6 response total_time Totalize Time Query Returns a quoted string indicating the amount of time accumulated in the current Totalize measurement interval Totalize...

Страница 275: ... Abbr clock_ter Arguments neg_2v 50 ohms to 2 volts gnd 50 ohms to ground ac 50 ohms via 0 01 µF capacitor to ground Example clock_term gnd clock_term Clock Termination Query Returns a character string indicating the current Analyzer clock input termination setup voltage Min Abbr clock_ter Returns neg_2v gnd ac Example clock_term command CLOCK_TERM GND response ...

Страница 276: ...d data_del_dn Data Delay Up Down Default This command pair is used to increment data_del_up or decrement data_del_dn the current DATA input delay by the default amount 0 005 nSec Min Abbr data_del_u data_del_d Argument none Example data_del_up data_del_dn ...

Страница 277: ...Argument v NR3 0 1E 9 to 3 99E 9 in 0 005E 9 steps Example data_del_up 0 02E 9 data_del_dn 0 10E 9 data_delay v Data Delay Sets the Analyzer DATA input delay to any value from 0 0 nS to 3 99 nS in 0 005 nSec steps Note that v is expressed as a real number with an exponent of 9 Min Abbr data_dela Argument v 0 00E 9 to 3 99E 9 in 0 005E 9 steps Example data_delay 1 62E 9 data_delay Data Delay Query ...

Страница 278: ...bbr data_te Arguments neg_2v 50 ohms to 2 volts gnd 50 ohms to ground ac 50 ohms via 0 01 µF capacitor to ground Example data_term ac data_term Data Termination Query Returns a character string indicating the current Analyzer data input termination setup Min Abbr data_te Returns neg_2v gnd ac Example data_term command DATA_TERM AC response ...

Страница 279: ...Up Down This pair of commands increments data_thr_up or decrements data_thr_dn the current Analyzer DATA input threshold by an amount v Min Abbr data_thr_u data_thr_d Arguments v 0 05 to 2 50 in 0 05 V steps Examples data_thr_up 0 10 increments threshold by 0 1 volt data_thr_dn 2 00 decrements threshold by 2 volts data_thres v Data Threshold Sets the threshold voltage for the Analyzer DATA input t...

Страница 280: ...ta_del_dn the current REF DATA delay by the default increment of 0 1 nSec Min Abbr rdata_del_u rdata_del_d Arguments none Examples rdata_del_up rdata_del_dn rdata_del_up v and rdata_del_dn v Reference Data Delay Up Down This command pair is used to increment rdata_del_up or decrement rdata_del_dn the current REF DATA delay by v where v is in NR3 format and may be set in the range 0 1 nSec to 3 99 ...

Страница 281: ...the current Analyzer REF DATA input delay Min Abbr rdata_dela Returns NR3 Example rdata_delay command RDATA_DELAY 1 10E 9 response rdata_term neg_2v gnd ac Reference Data Termination Sets the Analyzer REF DATA input termination Min Abbr rdata_te Arguments neg_2v 50 ohms to 2 volts gnd 50 ohms to ground ac 50 ohms via 0 01 µF capacitor to ground Example rdata_term neg_2v rdata_term Reference Data T...

Страница 282: ...increment rdata_thr_up or decrement rdata_thr_dn the current REF DATA threshold by v where v is in NR2 format and may be set in the range 0 05 to 2 50 Volts in 0 05 V steps Min Abbr rdata_thr_u rdata_thr_d Argument v NR2 0 05 to 2 50 volts in 0 05 V steps Examples rdata_thr_up 0 10 rdata_thr_dn 0 50 rdata_thres v Reference Data Threshold Sets the threshold voltage for the Analyzer REF DATA input t...

Страница 283: ...1400 User Manual C 65 rdata_thres Reference Data Threshold Query Returns the current threshold voltage for the Analyzer REF DATA input Min Abbr rdata_thre Returns NR2 Example rdata_thres command RDATA_THRES 1 00 response ...

Страница 284: ... Arguments auto Auto Search on pattern re alignment enabled off Auto Search off pattern re alignment enabled disab Auto Search off pattern re alignment disabled Example auto_search auto auto_search Auto_Search Query Returns a character string representing the current setup of AUTO SEARCH and automatic pattern re alignment Min Abbr auto_s Returns auto off disable Example auto_search command AUTO_SE...

Страница 285: ...the Auto Search mode for finding the Data Delay Arguments ber Uses the Bit Error Rate to find the Data Eye Crossing fast Uses the Clock to Data Phase to quickly find the Data Crossing Example auto_mode ber auto_mode Returns the Auto Search Data Delay mode Response BER or FAST ...

Страница 286: ... Data Bits to Sample when Auto Search is in BER mode This is the exponent for the number of Bits accumulated at the Delay Settings in terms of 10E n Arguments n 4 to 11 Example auto_sample 4 auto_sample Returns the exponent of the number of Data Delay Sampling Bits Response NR1 Numeric ...

Страница 287: ...e auto_thresh 3 auto_thresh Returns the exponent of the number used as the Data Delay Error Rate Threshold Response NR1 Numeric auto_width Returns the Width of the Data Eye as determined by Auto Search in either mode These values are in terms of seconds Example 100E 12 is 100 pS The following delay error codes are returned if appropriate 1 Only 1 Data Eye Crossing found 2 No Data Eye Crossing foun...

Страница 288: ...Error Rate Total window selects the Window display mode Window Error Rate Total test selects the Test display mode Test Error Rate Total Example disp_select test disp_select Display Select Query Returns a character string that indicates the current display mode of the Analyzer Min Abbr dis Returns total window test Example disp_select command DISP_SELECT TEST response error_reset Error Reset This ...

Страница 289: ... state of the BIT error history indicator Min Abbr histry_b Returns on off Example histry_bits command HISTRY_BITS OFF response histry_clear History Clear This command clears resets all four Analyzer history LEDs Sync Loss Bit Error Phase Error and Power Loss Min Abbr histry_c Arguments none Example histry_clear ...

Страница 290: ...rns on off Example histry_power command HISTORY_POWER OFF response histry_stat History Status Query This command returns a summary of the Analyzer s front panel status The response will be in the form of multiple message units separated by semicolons Min Abbr histry_st Returns Window error rate NR3 Totalize error rate NR3 Received clock frequency NR3 Sync Lock status on off History status indicato...

Страница 291: ...y Returns on off Example histry_sync command HISTRY_SYNC OFF response sync Synchronization Query Returns a character string indicating whether the Analyzer synchronization LOCK LED is on or off If it is on then the Analyzer is in pattern synchronization If it is off then the Analyzer is out of pattern synchronization Min Abbr sy Returns on off Example sync command SYNC ON response ...

Страница 292: ...ied in the string s The string will be in 24 hour format HH MM SS enclosed in single or double quotes This command sets the timed test interval This interval will be in effect only when the test mode is timed or repeat Min Abbr test_l Arguments t qstring in format hh mm ss where hh hours 0 to 24 mm minutes 0 to 59 ss seconds 0 to 59 Example test_length 02 00 00 test_length Test Length Query Return...

Страница 293: ...y after test length has elapsed This process will continue until a test stop command is received or testing is stopped manually from the front panel or by power loss Example test_mode timed test_mode Test Mode Query Returns the current Analyzer test timing mode Min Abbr test_m Returns untimed timed repeat Example test_mode TEST_MODE TIMED test_prev current previous Test Previous Sets test_prev par...

Страница 294: ...n progress the report will be based on current interval results If no test is in progress then the report will be based on results from the previous interval and will be an End of Test summary Min Abbr test_pri Arguments none Example test_print test_report eot on_error both none Test Report This command enables or disables End of Test and On Error reports Min Abbr test_r Arguments eot End of Test ...

Страница 295: ...ts on On Error reports will be squelched after 10 consecutive reports that is 10 consecutive seconds in which BER is above the Test Error Rate threshold On Error reports will then be automatically unsquelched after five consecutive seconds in which BER is not above the Test Error Rate threshold off On Error report squelching is disabled Example test_squelch on test_squelch Test Squelch Query Retur...

Страница 296: ...est mode stop Stops the test measurement process Will terminate untimed or repeat tests Will also prematurely end timed tests before test length has elapsed Example test_state run test_state Test State Query Returns a character string indicating the current state of the test process A response of RUN indicates that a test is in progress A response of STOP indicates that no test is in progress Min ...

Страница 297: ...Error reports are generated Min Abbr test_t Arguments v NR1 in the range 2 3 16 That is the test error rate threshold may be set in the range 10 2 to 10 16 Example test_thres 12 test_thres Test Threshold Query Returns the value v indicating that the current test error rate threshold is set to 1 x 10 v Min Abbr test_t Returns NR1 Example test_thres command TEST_THRES 12 response indicating that the...

Страница 298: ...value v indicating that the BER window bit length parameter is set to 1 x 10v bits Min Abbr win_bit_ Returns NR1 Example win_bit_len command WIN_BIT_LEN 15 response win_bits Window Bits Returns the total number of bits evaluated so far in the BERwindow interval Min Abbr win_bits Returns NR1 Example win_bits command WIN_BITS 49098302 response win_error Windows Errors Returns the total number of bit...

Страница 299: ...ns bits sec Example win_mode command WIN_MODE BITS response win_prev current previous Window Previous Sets the WIN_PREV parameter to current or previous This parameter determines whether Analyzer responses to win_bits win_error win_rate and win_time queries will be based on the current window interval or the previous window interval Min Abbr win_p Arguments current selects the current window inter...

Страница 300: ... NR3 Example win_report on off Windows Report This command enables or disables End of Window reports Min Abbr win_re Arguments on enables End of Window reports off disables End of Window reports Example win_report on win_report Windows Report Query Returns a character string indicating whether End of Windows reports are enabled on or disabled off Min Abbr win_re Returns on off Example win_report c...

Страница 301: ...ry Returns a quoted string indicating the value of the BER window seconds length parameter Min Abbr win_s Returns qstring Example win_sec_len command WIN_SEC_LEN 00 30 00 response win_time Windows Time Query Returns either the elapsed time in the current BER window so far or the duration of the previous BER window depending on the setup of the WIN_PREV parameter Min Abbr win_t Returns qstring in t...

Страница 302: ... set to on Min Abbr print_e Arguments on enabled reports will print off no reports will print Example print_enable on print_enable Print Enable Query Returns the current state of the Print Enable parameter Min Abbr print_e Returns on off Example print_enable command PRINT_ENABLE ON response print_port parallel gpib serial Print Port This command selects the port on which all Analyzer reports will ...

Страница 303: ... Min Abbr print_p Returns parallel gpib serial Example print_port command PRINT_PORT PARALLEL response print_string s Print String This command prints a character string s to the currently selected printer port Min Abbr print_s Arguments s a character string enclosed in quotes Example print_string This is a test ...

Страница 304: ..._rat_dn v Audio Rate Up Down This command pair is used to increment audio_rat_up or decrement audio_rat_dn the exponent of the error beeper BER threshold by an amount v Note that because the exponent is negative the audio_rat_up command decreases the BER threshold while audio_rat_dn increases the threshold Min Abbr audio_rat_u audio_rat_d Arguments v 1 2 3 14 Example audio_rat_up 9 The above examp...

Страница 305: ...audio_vol v Audio Volume Sets the volume of the error beeper to v where v can range from 0 off to 4 maximum volume Min Abbr audio_vol Arguments v 0 1 2 3 or 4 Example audio_vol 4 audio_vol Audio Volume Query Returns a decimal number in the range 0 1 2 3 or 4 that represents the current error beeper Min Abbr audio_vol Returns NR1 Example audio_vol command AUDIO_VOL 4 response ...

Страница 306: ...t error beeper volume by one level Min Abbr audio_vol_u audio_vol_d Argument none Example audio_vol_up audio_vol_dn audio_vol_up v and audio_vol_dn v Audio Volume Up Down This command pair is used to increment audio_vol_up or decrement audio_vol_dn the current error beeper volume by v levels Min Abbr audio_vol_u audio_vol_d Argument v NR1 1 2 3 or 4 Example audio_vol_up 2 audio_vol_dn 2 ...

Страница 307: ...e argument is a quoted character string Min Abbr date Arguments yyyy year NOTE may be above 2000 mm month 1 2 12 dd day 1 2 31 Example date 2001 03 21 date Date Query Returns a quoted string that indicates the current date setup of the Analyzer in year month day format Min Abbr date Returns qstring Example date command DATE 2001 03 02 response ...

Страница 308: ...i Arguments s qstring in the format hh mm ss where hh hours 00 23 mm minutes 00 59 and ss seconds 00 59 Examples time 16 30 02 time Time Query Returns a quoted string indicating the current setting of the instrument s time of day clock Min Abbr ti Returns qstring Example time command TIME 16 30 11 45 response ...

Страница 309: ...ds Therefore word commands have limited application in instruments equipped with the 1 MB Option However word commands will still function in units equipped with the 1 MB Option This insures that a Generator or Analyzer equipped with the 1 MB Option can replace a standard unit in automated applications designed to use standard short word commands Commands specific to I MB Option When the 1 MB Opti...

Страница 310: ...0 to 131071 1M mode 0 to 65535 512K mode 0 to 32767 256K mode 0 to 16 383 128K mode 0 to 8191 64K mode i NR1 in the range 1 to 80 the number of bits to overwrite 10 Bytes maximum b1 bn non decimal numeric s Indicating the bytes that make up the overwrite pattern Each byte may be in the range H00 to HFF hex Q000 to Q377 octal or B00000000 to B11111111 binary Example byte_block 4096 24 HBB H10 HFF N...

Страница 311: ...rent word pattern a 0 to 131071 1M mode 0 to 65535 512K mode 0 to 32767 256K mode 0 to 16 383 128K mode 0 to 8191 64K mode Min Abbr byte_b Response a i b1 b2 in format NR1 NR1 non dec numeric s Example byte_block 500 BYTE_BLOCK 500 16 H12 HF1 NOTE If address a is within 10 bytes of the end of the pattern then less than 10 bytes will be returned Also if the last byte of the pattern is included in t...

Страница 312: ...he block of bits to be deleted begins at this address 0 to 131071 1M mode 0 to 65535 512K mode 0 to 32767 256K mode 0 to 16 383 128K mode 0 to 8191 64K mode i NR1 in the range 8 to 80 in steps of 8 this is the number of bits to delete Example byte_delete 512 80 Note The address a plus the number of bytes being changed i 8 must be less than the pattern length Note n of bn must equal 1 8 ...

Страница 313: ...yte pattern May be in the range H00 to HFF hex Q000 to Q377 octal or B00000000 to B11111111 binary Example byte_edit 1000 Q320 byte_edit a Byte Edit Query Returns the hex octal or binary representation of the C bit section of the edit pattern at address a Note that if there is no editing session in progress this command will return the indicated byte from the current word pattern Min Abbr byte_e R...

Страница 314: ...attern of length i bits starting at address a in the edit pattern The insert pattern is indicated by bytes b1 bn Min Abbr byte_i Arguments a NR1 in the range a the insert pattern will be inserted at this address 0 to 131071 1M mode 0 to 65535 512K mode 0 to 32767 256K mode 0 to 16 383 128K mode 0 to 8191 64K mode i NR1 in the range 8 to 80 in steps of 8 the number of bits to insert b1 bn non decim...

Страница 315: ...ytes m is greater than 2047 then the number of added bits n must be set to 0 If m is greater than 16384 then n must be even byte_length Byte Length Query Returns the current length of the edit pattern in terms of whole bytes plus up to seven additional bits Note that if there is no editing session in progress this command will return the length of the current word pattern Min Abbr byte_l Returns N...

Страница 316: ...rs permit patterns of different lengths Arguments n 64 128 256 512 1024 64 10 Word memory buffers of 64 kbits locations 0 to 9 128 6 Word memory buffers of 128 kbits locations 0 to 5 256 3 Word memory buffers of 256 kbits locations 0 to 2 512 1 Word memory buffers of 512 kbits location 0 1024 0 Word memory buffers of 1024 kbits Example byte_mode 64 byte_mode Returns the current Word storage buffer...

Страница 317: ...ned and the maximum errors for the threshold Level BER Ratio errors bits 1 3 1E 2 256 8192 2 7 8E 3 256 32768 3 1 9E 3 256 131072 4 9 7E 4 256 262144 5 4 8E 4 256 524288 6 2 4E 4 256 1048576 7 1 2E 4 256 2097152 8 6 1E 5 256 4194304 9 3 0E 5 256 8388608 Min Abbr byte_s Arguments i NR1 in the range 1 highest BER to 9 lowest BER Example byte_sync 4 NOTE This command is found in the Analyzer command ...

Страница 318: ...in the scratch pad memory it can be edited uploaded to the controller or saved to the same or a different memory location You also must issue the edit_begin command before downloading a word pattern to the instrument Min Abbr edit_b Arguments n NR1 a decimal number in the range 1 to 9 where 1 indicates the current word pattern and 0 through 9 indicate the memory locations 1 only 1M and 512K modes ...

Страница 319: ...ting session in progress Example edit_cntrl command EDIT_CNTRL NONE response edit_end n Edit End You must issue this command to finish a 1 MB word editing session This command either moves the edited pattern from scratchpad memory to the current word location or saves the edited pattern into one of the instruments eight word memory locations You can also use this command to discard the edit patter...

Страница 320: ...Remote Commands C 102 GB1400 User Manual ...

Страница 321: ...nterface Device Settings For proper GPIB Interface communication and handshaking the GPIB controller system that controls the operation and the device GB1400 must have their addresses and terminating characters set up before use Each instrument on the GPIB interface bus needs a unique INSTRUMENT address programmed by GPIB ADDR key The INSTRUMENT address range for the GB1400 is 0 30 decimal The GPI...

Страница 322: ... standard D type 24 pin GPIB connector located on the rear panel All signals and pins conform to the standard GPIB pin out protocol Programming GPIB Remote Commands There are two types of remote commands for the GB1400 Set commands commands Queries commands queries The set commands force the GB1400 to take a specific action The query commands direct the GB1400 to return status information The cont...

Страница 323: ... reporting includes one additional register from what is specified within the IEEE 488 2 standard Status Byte There is a status byte which is used to define the SRQ status The individual bits within the status byte represent the different conditions which might cause the request for service defined as follows Bits 1 to 3 Unused Bit 4 TSB Test Event Status Bit This is a summary of Test Event Status...

Страница 324: ...he Standard Event Status Register represent the different possible causes of a Standard Event The bit definitions for the Standard Event Status Register are as follows Bit 1 Operation Complete Only set following an OPC command Bit 2 Request Control Not Used Bit 3 Query Error Set under the following conditions when output has been requested from the GB1400 and none is available when a command is se...

Страница 325: ...bit definitions for the Test Status Event Register are as follows Bit 1 End of Window condition Set at the end of each window period Bit 2 End of Test condition Set at the end of each Test Bit 3 Threshold Error condition Set whenever Test is running and Errored Second occurs where error rate is above Test Error Rate Threshold Bit 4 Synchronization Loss condition Set whenever SYNC LOSS occurs Bit 5...

Страница 326: ...same values from when it was last powered off No remote commands affect this The only exception to this is when the non volatile RAM becomes corrupted which should never happen during normal operation RAM corruption if it occurs will be displayed on the unit s LCD display When this happens the GB1400 will revert to its factory default settings Message Exchange The message exchange options are as f...

Страница 327: ...eric program data character program data non decimal numeric program data compound command program header and compound query program header are not handled Specific Command Implementations The reset command rst performs a device reset As defined in the IEEE 488 2 it will reset the device settings to default settings with the exception of stored memory locations and any remote interface settings Ma...

Страница 328: ...nds are provided to read back stored data memory contents Memory contents can be read back and printed out for hardcopy archiving RS 232 Interface Device Settings The RS 232C interface device settings are programmable through the front panel The following RS 232C parameters are programmable along with the default setting and other values Parameter Default Values Baud BPS rate 9600 4800 2400 1200 6...

Страница 329: ...ays high 7 GND Signal Ground 20 DSR Data Set Ready All other pins Not used Note Sent to the GB1400 a high level indicates that external device is ready to accept data from the unit This pin must be high or open for the BERT to transmit data This pin is pulled high internally by 27K Ohm to 12V RS 232 Interface Testing To test that the RS 232C interface is properly connected attach a standard 25 pin...

Страница 330: ...g All valid commands are executed Incorrect or unsupported commands are responded to by an error message RS 232C error messages follow after this section These command lines can contain either a single command or multiple commands The command line may contain both queries and commands Each individual command within the command line must be separated by semi colons parameters must be separated by c...

Страница 331: ...ut not valid for this interface Invalid Command Type Command mnemonic found but command issued incorrectly missing or added on end of command Too Few Parameters Missing parameter Too Many Parameter Too many parameters or training garbage at end of command Invalid Parameters Parameter invalid Parameter Out of Range Parameter out of range Parameter Not in Set Parameter not one of the values specifie...

Страница 332: ...Using GPIB RS 232 D 12 GB1400 User Manual ...

Страница 333: ... THE DOCUMENT OR ANY DESIGN OR TECHNICAL INFORMATION SHOWN THEREON NOR ANY RIGHT TO REPRODUCE THIS DOCUMENT OR ANY PART THEREOF EXCEPT FOR MANUFACTURE BY VENDORS FOR TEKTRONIX AND FOR MANUFACTURE UNDER THE CORPORATION S WRITTEN LICENSE NO RIGHT TO REPRODUCE THE DOCUMENT IS GRANTED UNLESS BY WRITTEN AGREEMENT WITH OR WRITTEN PERMISSION FROM THE CORPORATION Revision History Date Description Pages Af...

Страница 334: ...nce These instruments are not user adjustable If the GB1400 needs repair return it to Tektronix Recommended Test Equipment The recommended test equipment needed to verify performance is listed below Description Specification GB1400 Generator GB1400 Analyzer Coaxial SMA cables equal length Standard Instrument six each 50 Ohm 75 Ohm option four each 75 Ohm two each 50 Ohm ...

Страница 335: ...RX Not Clock 50 Ohm SMA coax TX Data RX Data 50 Ohm SMA coax TX Not Data RX Not Data 50 Ohm SMA coax 75 Ohm Option TX Clock RX Clock TX Not Clock RX Not Clock TX Data RX Data TX Not Data RX Not Data 50 Ohm SMA coax Use SMA to BNC adapters and 75 Ohm BNC coaxial cables See Figure 1 for Setup of Functional Test q Step 2 Reset both the Generator and Analyzer to their factory default settings Press th...

Страница 336: ... selected the PRBS LED light in the PATTERN section should be on If not press the PRBS key to select it q Step 5 At the Analyzer press the CLEAR key in the ERROR DETECTION section and the CLEAR key in the ERROR HISTORY section to clear the error display and the error history LED lights All four history LEDs should be off Because the Analyzer defaults to Autosearch mode the Analyzer and the Generat...

Страница 337: ...all step sizes Confirmation of Selectable Data Patterns q Step 11 In the Generator PATTERN section verify that the PRBS LED light is on If not press the PRBS key to select it q Step 12 Press the Generator PATTERN up down keys to select PRBS pattern PN7 q Step 13 Verify that the Analyzer displays the same PRBS pattern as the Generator q Step 14 At the Analyzer press the CLEAR key in the ERROR HISTO...

Страница 338: ...ep 22 In the Generator OUTPUT section the DATA LED should be on If not press the DATA key The INVERT DATA LED should be off If it is not press the key to turn it off q Step 23 Use the Generator BASELINE OFFSET up down keys to set the baseline offset value shown in the Generator Baseline Offset column of the Data Levels table q Step 24 Use the AMPLITUDE up down keys to set the amplitude to the valu...

Страница 339: ... to clear the totalize error display q Step 35 Wait 15 seconds then confirm that the error rate displayed on the Analyzer matches the Generator injected error rate and that the Analyzer BIT LED in the ERROR HISTORY section is lighted q Step 36 In the Generator ERROR INJECTION section press the RATE key once to select the next error rate q Step 37 Repeat steps 33 through 35 until all Generator erro...

Страница 340: ...the UP and DOWN arrow keys to select the different PN values c Wait for the Analyzer LOCK light to come on d Confirm the Analyzer threshold display falls within the limits shown in the Termination Threshold Limits table e Press F2 on the Analyzer to select CLOCK inputs and confirm that the F2 LED is lighted and repeat steps a through d Note The threshold limits listed assume that the Generator is ...

Страница 341: ...Performance Verification GB1400 Acceptance Test E 9 ...

Страница 342: ...tor LEDs Section ON OFF CLOCK FREQUENCY RECALL SAVE EXT PATTERN PRBS WORD RECALL SAVE WORD LENGTH F1 F4 Bits 1 8 OUTPUT DATA CLOCK INVERT DATA ERROR INJECT RATE Left Side PANEL LOCK GPIB ADDR LOCAL q Step 51 Verify the Generator LEDs and buttons operate by toggling the following buttons and observing the LEDs turn ON and OFF Section LED Button Indicator Left Side PANEL LOCK GPIB ADDR ON OFF ON OFF...

Страница 343: ... GB1400 Acceptance Test E 11 q Step 52 Verify the Analyzer LEDs and buttons operate by toggling the following buttons and observing the LEDs turn ON and OFF Section LED Button Indicator Left Side PANEL LOCK ADDR ON OFF ON OFF ...

Страница 344: ...through the GPIB interface How to Recall Factory Default Settings Using Front Panel Controls Use the following procedure to recall the factory default settings of the Generator or Analyzer using front panel controls 1 Turn instrument power off 2 While holding down the WORD CLEAR BIT 1 and VIEW ANGLE keys simultaneously turn instrument power back on 3 After you see the message Default Settings appe...

Страница 345: ...z 5 1360 MHz 6 680 MHz 7 340 MHz 8 170 MHz 9 85 MHz Frequency Step Size 1000 0 MHz Data Pattern PRBS pattern PN 7 27 1 Word memory all ten AA 55 Programmable Data Pattern AA 55 Current Pattern Setting PRBS Data Invert OFF Word Order LSB CLOCK DATA Outputs Output Clock Amplitude 1 50 V Clock Baseline Offset 0 75 V Output Data Amplitude 1 50 V Data Baseline Offset 0 75 V Error Injection Rate OFF ...

Страница 346: ...GPIB address Generator 15 GPIB Bus TALK_LISTEN GPIB terminator EOI LF RS 232C prompt BERT1400 RS 232C baud rate 9600 RS 232C parity even RS 232C data size 8 bits RS 232C EOL CR LF RS 232C echo OFF RS 232C prompt line feed OFF MISC View Angle 0 Panel Lock OFF Response Header ON ...

Страница 347: ...erence Data Termination GND Data Pattern PRBS pattern PN 7 27 1 Word memory all ten AA 55 Programmable Data Pattern AA 55 Current Pattern Setting PRBS Data Invert OFF Reference Data Mode OFF Word Order LSB Auto Search Pattern Synchronization Auto Search ON Auto Search Delay Mode FAST Auto Search Data Samples 10E 7 Auto Search Data BER Threshold 10E 6 Synchronization Disable OFF Error display selec...

Страница 348: ...ters Test Mode TIMED Test Length 00 00 30 Test Report Enable ON ERROR Test Error Rate Threshold 1 0E 05 Test Squelch OFF Previous Remote Status PREVIOUS Test Status Event Enable 0 Remote Intefaces Remote Mode LOCAL GPIB address 14 GPIB Off Bus Capability OFF GPIB Terminator EOI LF RS 232C Prompt BERT1400 RS 232C Baud Rate 9600 RS 232C Parity EVEN RS 232C Data Size 8 Bits RS 232C EOL CR LF RS 232C ...

Страница 349: ...Default Settings F 6 GB1400 User Manual MISC View Angle 0 Panel Lock OFF Response Header ON ...

Страница 350: ...t from the outside of the instrument with a soft clean cloth or small brush A brush is especially useful for removing dust from around the buttons and connectors Remove hardened dirt with a soft cloth dampened with a mild detergent and water solution Do not use abrasive cleaners Cleaning the CRT Clean the light filter and CRT face with a soft lint free cloth dampened with denatured alcohol Do not ...

Страница 351: ...Cleaning Instructions G 2 GB1400 User Manual ...

Страница 352: ...oose the OK button 5 The program will install and create a new Program Manager group 6 The README document is this document 7 The installation is complete What is MLPE MLPE is a specialized pattern editor that can be used with Tektronix gigaBERT700 1400 series and packetBERT200 BERT products It allows the user to create store edit and transfer user defined and created patterns to and from the BERT...

Страница 353: ...rmats Multiple editing windows can be open simultaneously to allow working on several files at once The editor runs under Microsoft Windows with full Windows printing capability Extensive built in help Data can be uploaded to a gB700 1400 1600 Tx or Rx via RS 232 or GPIB Uploaded data can be saved in any memory location for any memory configuration even while the instrument is performing tests Dat...

Страница 354: ... normally without any errors but the program fails to run properly check the following If you are using Norton Desktop 3 0 in the Tektronix program group select single mouse click the Pattern Editor icon and then select PROPERTIES in the GROUP menu Select the ADVANCED icon If the default path and directory was chosen for installation see if the listed STARTUP DIRECTORY shown is drive on which Wind...

Страница 355: ...gaBERT700 1400 1600 and want to use RS 232 to Upload or Download patterns your RS 232 cable should be wired as shown below gigaBERT RS 232 pin number 25 pin Comm Port 9 pin Comm Port 2 2 3 3 3 2 4 4 7 5 5 8 6 6 6 7 7 5 All other pins are not used GPIB This program has been designed to use National Instruments GPIB hardware It may not work or work properly with other brands of hardware Program Excl...

Страница 356: ...r read the gigaBERT to match the order of the file being sent If you should have a problem sending a pattern to a gigaBERT or receiving a pattern from a gigaBERT there may be a problem with the identification string that is stored in the gigaBERT Please consult the remote commands section of the respective manual for the instrument Normally unless you change the identification strings and prompt t...

Страница 357: ...Editor 1 Start Windows and remove the Tektronix group and all of its entries 2 Save the configuration 3 Open File Manager 4 Delete the following The MLPE directory and PATTERNS sub directory and all entries in each Delete the MLPE INI file in the WINDOWS directory 5 The program edits the PATH statement in the AUTOEXEC BAT file to add the WINDOWS SYSTEM directory to the path You can edit the file t...

Страница 358: ...EMENT BEFORE OPENING THE SEALED WRAPPER SURROUNDING THE PROGRAM If you cannot agree to the license terms promptly return the unopened package to Microwave Logic for a full refund Contact the nearest Microwave Logic Field Office for return assistance Copyright 1995 Microwave Logic inc Unpublished rights reserved under the copyright laws of the United States RESTRICTED RIGHTS LEGEND Use duplication ...

Страница 359: ... organization outside of Customer or the corporation of which Customer is a part without the prior written consent of Microwave Logic b Export or re export directly or indirectly the program any associated documentation or the direct product thereof to any country to which such export or re export is restricted by law or regulation of the United States or any foreign government having jurisdiction...

Страница 360: ...reof from Microwave Logic or such third party Upon termination by either party Customer shall return to Microwave Logic the Program and all associated documentation together with all copies in any form LIMITED WARRANTY Microwave Logic warrants that the media on which the Program is furnished and the encoding of the Program on the media will be free from defects in materials and workmanship for a p...

Страница 361: ...N IF MICROWAVE LOGIC OR SUCH OTHERS HAS ADVANCE NOTICE OF THE POSSIBILITY OF SUCH DAMAGES THIRD PARTY DISCLAIMER Except as expressly agreed otherwise third parties from whom Microwave Logic may have obtained a licensing right do not warrant the program do not assume any liability with respect to its use and do not undertake to furnish any support or information relating thereto GENERAL This Agreem...

Страница 362: ...ontrolling two VCOs Voltage Controlled Oscillator A microprocessor programs the loop prescale divider ratios Data Generator PCB The Data Generator PCB contains the circuitry required to generate the PRBS pattern programmable WORD clock distribution error inject circuitry and pattern sync generator The PRBS data generator utilizes a pattern dependent n length shift register where of 2n 1 with modul...

Страница 363: ...es the front panel DATA and DATA invert outputs The amplifier provides adjustment controlled by DACs of the Data output Amplitude and baseline Offset The amplifier will drive 2 Volts peak to peak into a 50 Ohm load unterminated 4 Volts peak to peak suitable for Fast TTL and CMOS The System Clock signal is sent to the Output Amp PCB distributed to the Data latch and also to a discrete GaAs FET puls...

Страница 364: ...TO SEARCH mode or manually through front panel control Data Generator PCB The Data Generator PCB contains the circuitry required to generate the local PRBS pattern or programmable WORD for comparison with the received pattern The locally generated pattern is compared bit by bit at full rate The differences are Bit Errors and are counted by the Error Counter PCB When the Bit Error Rate BER exceeds ...

Страница 365: ...as BER Total bit errors are also displayed along with frequency All counting is done at full rate latched and calculated by the CPU Common to both GB1400 TX and GB1400 RX CPU PCB The CPU PCB contains the CPU RAM and software PROMs The 80188 microprocessor handles all inter board communication storage and loading of the programmable 16 bit WORD error counting and frequency calculations internal clo...

Страница 366: ...R INJECT PATTERN SYNC DATA INVERT DATA OUT OFF AMPL DATA OUT DATA INHIBIT CPU BUS EXTERNAL ERROR INJECT FRONT PANEL 2 x 24 LCD DISPLAY CPU NON VOLATILE RAM POWER SUPPLY DC OUT AC INPUT PHASE A PHASE B REAR PANEL BATTERY CLK CLK CLK CLK CLK CLK SYNC EXT D Q Q R _ CPU BUS CLOCK 2 GB1400 Tx 0 1uf 50 Ohm F F F _ F 4 Figure I 1 Block Diagram GB1400 TX ...

Страница 367: ... MUX PRN GEN FEED SLIP ERRORS WORD GEN ERROR COUNTER SYNC CLK CLK SYNC SLIP CLK CLK DATA PATTERN SYNC ERROR OUT ERROR OUT FRONT PANEL 2 x 24 LCD DISPLAY cpu NON VOLATILE RAM POWER SUPPLY CPU BUS DC OUT CLOCK AC INPUT BATTERY DATA THRESHOLD REAR PANEL REAR PANEL 50ohm 50ohm 2V 2V AC 50ohm 2V GND CLOCK BAR LOAD NETWORK LOAD NETWORK AC 2V AC 50ohm 50ohm 2V AC AC REF THRESHOLD D Q Q _ D Q Q _ GB1400 R...

Страница 368: ...Glossary Index ...

Страница 369: ...on Bandwidth The difference between the limiting frequencies of a continuous frequency spectrum The range of frequencies handled by a device or system BER An acronym for Bit Error Ratio or Rate The principal measure of quality of a digital transmission system BER is defined as BER Number of Errors Total Number of Bits BER is usually expressed as negative exponent For example a BER of 10 7 means th...

Страница 370: ...signal elements In computers a clock synchronizes certain procedures such as communication with other devices Error Detection Checking for errors in data transmission A calculation is made on the data being sent and the results are sent along with it The receiving station then performs the same calculation and compares its results with those sent Code in which each data signal conforms to specific...

Страница 371: ...on Residual error rate The error rate remaining after attempts at correction are made RS 232C A physical layer interface standard for the interconnection of equipment Rx Receiver An abbreviation for Receiver A detector and electronic circuitry to change optical signals to electrical signals Tx Transmitter An abbreviation for Transmitter A driver and source used to change electrical signals to opti...

Страница 372: ...Glossary glossary 4 GB1400 User Manual ...

Страница 373: ...Definitions 3 42 Selecting Reference Data Mode 3 27 Single Ended or Differential Op 3 27 Star Stop Measurements 3 46 Synch LOCK Threshold 3 22 Test Process Setup 3 35 Totalize Process Setup 3 33 Viewing Results 3 36 Window Process Setup 3 34 Appendices BERT Primer Technical Articles B 1 Cleaning Instructions G 1 Customer Acceptance Test E 1 Default Settings F 1 Pattern Editing Software H 1 Remote ...

Страница 374: ...ut Equivalent Circuits 3 17 Generator Display 2 6 Nominal Generator Clock Data Waveforms showing Amplitude Baseline Offset and Vtop 3 13 Nominal Generator NRZ Data and Clock Output Waveforms 2 3 Seven stage PRBS generator B 6 TEST Measurement Process 3 32 Three stage PRBS generator B 5 TOTALIZE Measurement Process 3 30 WINDOW Measurements Process 3 31 Functional Overview 2 1 Functions common to TX...

Страница 375: ... 68 Test Reports REPORT 3 65 Test Squelch SQUEL 3 67 Test Threshold THRES 3 66 Test View Current VIEW CUR 3 70 Test View Previous VIEW PRE 3 69 Time Option DATE 3 84 Time Option TIME 3 85 Utility Option OPTION 3 82 Utility Version VER 3 83 Window Interval in Bits BITS 3 72 Window Interval in Hrs Min Sec SECOND 3 73 Window Mode MODE 3 71 Window Reports REPORT 3 74 Word Edit EDIT 3 56 Word Fill FILL...

Страница 376: ...54 How F2 F3 set Input Set up 3 24 How to Tell which Display Mode is Active 3 37 Input Terminations for CLOCK DATA and REF DATA 3 25 Input Threshold Range as a Function of Termination 3 26 Menu Descriptions 3 52 Output Setup Rules vs Termination Impedance 3 14 PRBS 2N 1 Test Patterns 3 3 PRBS Polynomials and Shift Register feedback taps for PB200 B 4 PRBS Polynomials Shift Register feedback taps G...

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