Racal Instruments 2251A Operator'S Manual Download Page 40

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3-11

3.7

Selecting the Measurement Function

3.7.1

Each measurement function is selected by a two-character code. Table 3.8 presents the
measurement function codes for the 2251A.

Table 3.8 - Measurement Function Codes

Function

Code

Frequency A

Frequency B

Frequency C

Period A

Time Interval A B

Totalize A by B

Ratio A/B

Ratio C/B

Rise Time A

Fall Time A

Positive Pulse Width A

Negative Pulse Width A

Phase A Rel B

Check

NOTE

Option 41 must be installed in the 2251A for FC and RC to be accepted as valid
commands.

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Summary of Contents for 2251A

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Page 2: ...1828 Racal Elektronik System GmbH Frankenforster Strasse 21 51427 Bergisch Gladbach 1 Germany Tel 49 2204 92220 FAX 49 2204 21491 Racal Australia Pty Ltd 3 Powells Road Brookvale NSW 2100 Australia Tel 61 2 9936 7000 FAX 61 2 9936 7036 Racal Electronics Pte Ltd 26 Ayer Rajah Crescent 04 06 07 Ayer Rajah Industrial Estate Singapore 0513 Tel 65 7792200 FAX 65 7785400 Racal Instruments Ltd Room 1213 ...

Page 3: ...t Racal Instruments support facility A list is located on the last page of this manual If you are unsure where to call contact Racal Instruments Inc Customer Support Department in Irvine California USA at 1 800 722 3262 or 1 949 859 8999 or via fax at 1 949 859 7139 We can be reached at helpdesk racalinstruments com PROPRIETARY NOTICE This document and the technical data herein disclosed are propr...

Page 4: ...nductor in the power cord Maintenance and calibration procedures sometimes call for operation of the unit with power applied and protective covers removed Read the procedures and heed warnings to avoid live circuit points Before operating this instrument 1 Ensure the instrument is configured to operate on the voltage at the power source See Installation Section 2 Ensure the proper fuse is in place...

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Page 6: ... 1 3 1 VXIbus Control 3 1 3 2 VXIbus Logical Address and Interrupt Level Assignment 3 1 3 3 2251A Home State 3 2 3 4 Functional Check 3 3 3 5 Output Message Format 3 4 3 6 Input Commands 3 6 3 7 Selecting the Measurement Function 3 11 3 8 Numerical Input Data 3 12 3 9 Resolution Control Selection 3 13 3 10 Signal Conditional Parameters 3 14 3 11 Measurement Control Codes 3 15 3 12 Store and Recall...

Page 7: ...equency Sensitivity Test Configuration 4 5 4 4 Input B High Frequency Sensitivity Test Configuration 4 6 4 5 Input C Test Configuration 4 7 4 6 Time Interval A B Test Configuration 4 8 4 7 Totalize A by B Test Configuration 4 9 4 8 Ratio A B Test Configuration 4 10 4 9 Ratio C B Test Configuration 4 11 4 10 Input A Trigger Level Test Configuration 4 12 4 11 Input B Trigger Level Test Configuration...

Page 8: ... 16 3 14 Special Function Codes 3 18 3 15 Using the Special Function 3 19 3 16 IEEE 488 2 Command Codes 3 20 3 17 STA Related Q Codes 3 23 3 18 2251A STA Response Description 3 24 3 19 2251A STA Error Code Set 3 25 3 20 Alphabetical List of 2251A Command Codes 3 26 4 1 Input A Sensitivity Low Frequency Test 4 3 4 2 Input A Sensitivity High Frequency Performance Limits 4 4 4 3 Input B Sensitivity L...

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Page 10: ...he measurement capabilities of the 2251A may be extended to include frequency measurements to 1 3 GHz with Option 41 1 1 3 The 2251A is designed to be controlled remotely over the VXIbus No local control of the counter is possible The command set the counter responds to is defined by Racal Instruments Refer to Section 3 of this manual for details of this command set 1 1 4 Refer to Figure 1 1 for a...

Page 11: ...ween device dependant commands to open and close the counter s gate 1 2 1 7 Ratio A B This measures the ratio of the frequencies applied to inputs A and B 1 2 1 8 Rise Fall A This measures the rise or fall time of a signal at input A depending on the slope selected 1 2 1 9 Pulse Width A This measures the interval between successive rising to falling or falling to rising edges depending on the trig...

Page 12: ... a measurement is provided by input D or the VXI trigger bus Arming conditions are selected by the use of special functions available in the command set 1 3 2 2 External Frequency Standard Input The 2251A may be locked to an external reference frequency applied to this input Selection of the reference frequency is under software control 1 3 2 3 Math Function When the math function is active the 22...

Page 13: ...allows the 2251A to be synchronized to any integer sub multiple of an external 10 MHz reference e g 1 2 2 5 5 MHz 1 4 1 3 Option 11 This option provides a 0 1 ppm 10 MHz internal reference The internal reference is also output on the front panel for external use Option 11 and Option 10 are mutually exclusive 1 4 1 4 Option 41 Channel C This option extends the frequency measurement range to 1 3 GHz...

Page 14: ...ivity Sinewave X1 25 mV rms to 100 MHz 0 55EC 50 mV rms to 200 MHz 0 30EC 60 mV rms to 200 MHz 30 45EC 70 mV rms to 200 MHz 45 55EC Sensitivity Pulse X1 75 mV pp at 5 ns pulse width Dynamic Range X1 36 dB to 50 MHz 75 mVpp to 5 Vpp 30 dB to 100 MHz 75 mVpp to 2 5 Vpp 24 dB to 200 MHz 150 mVpp to 2 5Vpp Maximum Input 50 ohm input 5 V rms Maximum Input 1 Megohm input X1 260 V DC AC rms DC to 2 kHz d...

Page 15: ...rms 1 5 2 Trigger Conditions Automatic or manual selection in the 5 1 V to 5 1 V range X1 51 V to 51 V range X10 Trigger Level Range X1 5 1 V in 20 mV steps X10 51 V in 200 mV steps Trigger Level Accuracy X1 1 of Trigger Level 30 mV X10 1 of Trigger Level 300 mV Autotrigger Minimum Amplitude 150 mV pp Autotrigger Frequency Range DC 50 Hz to 160 MHz typically to 200MHz Artisan Technology Group Qual...

Page 16: ... 3 2 Frequency C Option 41 Range 40 MHz to 1 3 GHz LSD 1 ns Gate Time x Freq Resolution 1 ns Gate Time x Freq Accuracy Resolution Timebase Error x Freq 1 5 3 3 Period A Range 5 ns to 1 7 x 10 sec 3 LSD 1 ns Gate Time x Period Resolution 2 x LSD 1 4 x Trigger Error Gate Time x Period Accuracy Resolution Timebase Error x Period Refer to Notes and Definitions Artisan Technology Group Quality Instrume...

Page 17: ...Resolution LSD 1 ns Start Trigger Error Stop Trigger Error Accuracy Resolution Timebase Error x Time Interval Trigger Level Setting Error 2 ns 1 5 3 5 Totalize A By B Range 100 MHz 1 to 10 1 events 12 Pulse Width 5 ns min at trigger points Maximum Rate 10 events sec 8 Start Stop Input B LSD 1 count Resolution LSD Accuracy LSD Refer to Notes Definitions Page Changed 3 10 99 Artisan Technology Group...

Page 18: ...or B Gate Time Accuracy LSD Trigger Error B Gate Time 1 5 3 8 Rise Fall Time Range 20 ns to 20 ms Rise Time Start slope 10 trigger point Stop slope 90 trigger point Fall Time Start slope 90 trigger point Stop slope 10 trigger point Input Channel Input A Minimum Pulse Height 500 mV pp Minimum Pulse Width 20 ns at signal peaks LSD displayed 1 ns 100 ps using averaging mode Resolution LSD 1 ns Start ...

Page 19: ...trigger point Input Channel Input A Minimum Pulse Height 150 mV pp LSD 1 ns 100 ps using averaging mode Resolution LSD 1 ns Start Trigger Error Stop Trigger Error Accuracy Resolution Trigger Level Timing Error Trigger Level Setting Error 2 ns Timebase Error x Pulse Width 1 5 3 10 Phase A Rel B Range 0 1 to 3600 LSD 0 1 to 1 MHz 0 1 to 10 MHz 0 10 to 100 MHz 0 Resolution LSD TI Resolution x 360E Pe...

Page 20: ...pp Resolution X1 20 mV Accuracy Sinewave 6 of pk pk voltage 50 mV Accuracy DC 1 of reading 40 mV 1 5 4 Averaging Mode May be applied to all functions except totalize Adds an extra digit of resolution Sample Size 100 1 5 5 Math May be applied to all counting timing measurement functions except Trigger Level and Gate Time Result Reading X Y Z where X Y and Z are constants entered by the operator Con...

Page 21: ...frequencies that are subharmonics of 10 MHz 1 5 8 External Arming Applicability All functions except phase pulse width rise fall time can be armed Input Signal TTL available from front panel BNC or 8 TTLTRGbus lines selected under program control Arming Mode 1 Start Off Stop Off 2 Start Positive Stop Off 3 Start Negative Stop Off 4 Start Positive Stop Positive 5 Start Negative Stop Positive 6 Star...

Page 22: ...nsions 10 3 H x 1 188 W x 13 775 D Not including ejector handles 1 5 13 Weight Approximately 3 lbs 1 5 14 Options 1 5 14 1 Option 10 External Frequency Standard Multiplier Phase locked frequency multiplier enabling 1 2 5 or 10 MHz to be used as the external standard Frequency Input 1 2 5 or 10 MHz 10 ppm Signal Level 100 mV rms sinewave min 10V rms max Maximum Input Levels 400V peak up to 500 Hz d...

Page 23: ...se 115dBc Hz 10 Hz 145dBc Hz 100 Hz 150dBc Hz 1KHz 10KHz NOTE Options 10 and 11 are mutually exclusive 1 5 14 3 Option 41 1 3 GHz Input C Factory installed option extending the counter range to 1 3 GHz Frequency Range 40 MHz to 1 3 GHz Refer to Sections 1 5 1 and 1 5 3 2 for additional specifications 1 6 Definitions and Notes 1 6 1 Trigger Error Trigger Error SQR e e i n 2 2 Input slew rate at tri...

Page 24: ... 6 5 Timebase Error 1 6 5 1 The fractional deviation of the timebase frequency from 10 MHz is due to ageing temperature voltage variations etc This is determined by the reference frequency used by the 2251A The default reference frequency is the VXIbus CLK10 signal 1 6 6 Resolution Gate Time 1 6 6 0 1 Gate time is related to the resolution selected in the Frequency Period Ratio and Check functions...

Page 25: ...ange This precludes unnecessary shifting of digits NOTE 2 Measurements of frequency period ratio and check are averaged when these gate times are set 1 6 6 1 The resolution of phase and totalize is determined by the input signal 1 6 6 2 Time interval rise fall time and pulse width measurements have the resolution determined by both the input signal and the resolution set 1 6 6 3 Resolution is prog...

Page 26: ...r should it be necessary to return your product for servicing call 1 800 722 3262 or call 714 859 8999 and ask for Customer Support You may also contact Customer Support via E Mail at customer_service rdii com If parts are required to repair the product at your facility call 1 800 722 3262 and ask for the Parts Department When sending your instrument in for repair complete the form in the back of ...

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Page 28: ...tic spray foam to surround and protect the instrument Reship in either the original or a new sturdy shipping carton 2 4 Interrupt Level and Logical Address Setting 2 4 1 The Interrupt Level and Logical Address of the 2251A are not software controllable Carry out the following procedure if it is necessary to change either the Logical Address or the Interrupt Level 2 4 2 To set the interrupt level o...

Page 29: ... to the mainframe with the captive screws provided at the top and bottom edges of the counter 2 5 2 1 Poor mechanical alignment of 2251A rear connectors P1 and P2 may require the counter be reseated in the VXI mainframe Do NOT use undue force to seat the counter 2 5 3 Power up the mainframe Ensure the SYSFAIL LED on the 2251A front panel lights and extinguishes after a few seconds to show the coun...

Page 30: ...ddress and Interrupt Level Assignment 3 2 1 Refer to Section 2 4 of this manual for instructions on setting the Logical Address and Interrupt Level Although there are a variety of Resource Managers and their display formats vary it is recommended that the user verify the Logical Address and Interrupt Level by viewing the configuration returned after start up Artisan Technology Group Quality Instru...

Page 31: ... Inputs A and B Measurement Mode Frequency A Time Interval Delay 200 Fs Disabled Gate Time 100 ms 8 Digits Input Impedance 1 Megohm Inputs A and B Input Attenuation X1 Inputs A and B Math Constants X 0 Y 1 Z 1 Math Disabled Input Mode Separate Inputs Input A Low Pass Filter Off Input A Trigger Slope Positive Input B Trigger Slope Positive Measurement Hold Continuous RQS Assertion Off Input Source ...

Page 32: ...Write protocol of the VXIbus Specification to which the counter conforms The command WSRd indicates that data is to be read from the 2251A using the VXIbus specified Word Serial Read protocol 3 4 2 VXIbus Communication Check Perform the following procedure a Power on the counter b Test as shown below Action Command Send the IEEE 488 2 WSWrt 03 command TST TST LF c Verify the TRIG A LED and the GAT...

Page 33: ...e 21 bytes long They are of the form aa nnnnnnnnnnnn E m cr f where aa is a 2 byte header that describes the measurement mode the 2251A is in or the type of data recalled Refer to Tables 3 1 and 3 2 for the headers the 2251A can generate describes the polarity of the measurement result nnnnnnnnnnnn is numerical data n 0 to 9 or a decimal place Leading zeros will be added to ensure that 11 bytes ar...

Page 34: ...Frequency B FB Frequency C See Note FC Period A PA Time Interval A B TI Totalize A by B TA Ratio A B RA Ratio C B See Note RC Rise Time A RT Fall Time A FT Positive Pulse Width A PW Negative Pulse Width A NW Phase A Rel B PH NOTE Option 41 must be fitted for the 2251A to be able to generate FC or RC Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com ...

Page 35: ...the signal when Special Functions 51 and 52 respectively are enabled 3 6 Input Commands 3 6 1 Introduction The 2251A responds to device dependent commands in a deferred mode This means the 2251A continues to accept commands until a terminating character or message is received then the entire string will be executed To insure that the commands have been processed a OPC command can be given and then...

Page 36: ...iption Table 3 19 2251A STA Error Code Set Table 3 20 Alphabetical List of Command Codes Device dependent commands are executed sequentially beginning with the first one sent and ending with the last If more than one command is to be sent no delimiters are required If necessary commas spaces and semicolons may be included in the command strings for clarification without affecting counter operation...

Page 37: ...Levels AMN BMN Manual Set to 0 00 V Input Coupling AAC BAC AC Inputs A and B Inputs A and B Impedance 1 MS AHI BHI Inputs A and B Input Attenuation AAD BAD X1 Input A Low Pass Filter Off AFD Input A and B Trigger Slope APS BPS Positive Input Mode A and B Separate BCS Math Constants MD X 0 Y 1 Z 1 Math Disabled Continuous Measurement Mode T0 SRQ Assertion Disabled Q0 Time Interval Delay DD 200 Fs D...

Page 38: ...d S80 Table 3 6 Instrument Preset Code Function Code Sets counter functions and settings to Home State IP NOTE Some of the device dependent commands in the following tables require additional numerical input data Such numerical input follows its command and is indicated by an asterisk in the tabulations Numerical Input format is described in Table 3 7 Home state commands are underlined in all of t...

Page 39: ...may have up to nine digits and a decimal point The decimal point is not essential After entry of nine digits without a decimal point additional digits are ignored and a programming error is generated Excess digits that are truncated will still increase the power of ten stored Also if fewer than nine digits are needed unused bytes may be omitted 4 Spaces or nulls entered between bytes 11 and 12 are...

Page 40: ...n Code Frequency A FA Frequency B FB Frequency C FC Period A PA Time Interval A B TI Totalize A by B TA Ratio A B RA Ratio C B RC Rise Time A RT Fall Time A FT Positive Pulse Width A PW Negative Pulse Width A NW Phase A Rel B PH Check CK NOTE Option 41 must be installed in the 2251A for FC and RC to be accepted as valid commands Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SO...

Page 41: ... 10 9 10 10 9 NOTES 1 Entered numbers will be rounded up before storage as follows a Trigger Level X1 to next multiple of 20 mV b Trigger Level X10 to next multiple of 200 mV c Delay gate time to next multiple of 25 6 Fs 2 Resolution entries are rounded down to the next integer Refer to Table 3 10 for resolution numbers and related gate times 3 Math constant Z can be set to 0 However an error mess...

Page 42: ...51A resolution control selection Table 3 10 Resolution Control Selection Command Code To Number of Selected Select Resolution Digits in Frequency Number of Digits Period Ratio and Check Gate Time SRS 10 10 10 s SRS 9 9 1 s SRS 8 8 100 ms SRS 7 7 10 ms SRS 6 6 1 ms SRS 5 5 1 ms SRS 4 4 1 ms SRS 3 3 1 ms NOTES 1 The most significant digit is permitted to exceed the resolution by 1 digit providing a ...

Page 43: ... Input A AFD AFE COM A Disable Enable BCS BCC DC AC Coupling A ADC AAC DC AC Coupling B BDC BAC 1 MS 50S Impedance A AHI ALI 1 MS 50S Impedance B BHI BLI Slope A Pos Neg APS ANS Slope B Pos Neg BPS BNS X10 Attenuator A Disable Enable AAD AAE X10 Attenuator B Disable Enable BAD BAE Manual AUTO TRIG A AMN AAU Manual AUTO TRIG B BMN BAU Artisan Technology Group Quality Instrumentation Guaranteed 888 ...

Page 44: ...SFD SFE Reset measurement RE NOTES 1 In continuous measurement mode the output buffer is updated at the end of each gate period If the buffer is being read when the gate period ends updating is delayed until reading is complete 2 In single measurement mode the output buffer is cleared every time a T2 command is received 3 In making manual totalize measurements T2 and T3 commands are used with the ...

Page 45: ...l math constant Y SMY RMY Defaults to 1 Store Recall math constant Z SMZ RMZ Defaults to 1 Store Recall arming delay time SDT RDT Defaults to 200 Fs Store Recall gate time SGT RGT Defaults to 100 ms Store Recall memory 0 through 9 SM RM See NOTE 2 Store Recall special function S RSF Defaults to all SFs off NOTES 1 Recalled values do not cause the Reading Ready bit in the status byte to be set nor ...

Page 46: ...be entered into the special function register but only the second digit of the special function number is stored The first digit of the special function number is indicated by the position in the output string The default state has 0 s entered in all positions The special function output string is generated in response to the RSF command code 3 13 2 Special function numbers must be entered into me...

Page 47: ...to trigger measurement 50 Selects Mean Amplitude Measurement Mode 51 Selects Positive Peak Amplitude Mode 52 Selects Negative Peak Amplitude Mode 60 Totalize A by B When in TA 61 Manual Totalize When in TA 70 Basic 10 MHz Check 72 Start TEC short continuous calibration display shows TEC count Must enable CK mode 73 Start TEC long continuous calibration display shows TEC count Must enable CK mode 7...

Page 48: ...ions are enabled immediately enables that special function 2 In Special Function 21 Frequency B is specified to 160 MHz only Period B is specified to 6 25 ns only Totalize B by A operates for one complete cycle of Input A 3 Special Functions 77 and 78 require connection of a 10 MHz internal standard to Input A or B Refer to Section 4 1 5 1 for a description of required signals 3 13 4 Recalling the...

Page 49: ...t Status Byte STA old 2251 Status Byte NOTE NRf is a numerical input in the range of 0 to 255 Complies with IEEE 488 2 Section 7 7 2 for the accepted input formatting 3 14 1 IDN Respond with the 2251A s Identify string e g RACAL INSTRUMENTS 2251A 0 19 1 3 14 2 RST Preset the 2251A to a know state See Table 3 5 Instrument Preset Conditions 3 14 3 TST Command the 2251A to do an Internal Self Test Th...

Page 50: ...ond with the Operation Complete Bit in the ESR being Set after the 2251A has completed all pending commands Reading the ESR will clear the OPC bit 3 14 11 OPC This command will respond with a 1 after the 2251A has completed all pending commands 3 14 12 WAI Wait for the 2251A to complete all pending commands 3 14 13 TRG Trigger the 2251A to start a measurement Used with the T1 Command and the same ...

Page 51: ...These are shown in Figure 3 1 which is a replica of Figure 11 8 in the IEEE 488 2 1987 Specification Figure 3 1 IEEE 488 2 Status Reporting Model NOTE Bit 0 of the Status Byte is asserted via Bit 7 SRQ Bit of the Device Dependent Status Byte See Section 3 16 below Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com ...

Page 52: ...17 STA Related Q Codes Function Code DDSB generation inhibited Q0 DDSB generation upon error detected Q1 DDSB generation for measurement ready Q2 DDSB generation for measurement ready or error detected Q3 DDSB generation for frequency standard change Q4 DDSB generation for frequency standard change or error detection Q5 DDSB generation for measurement ready or frequency standard change Q6 DDSB gen...

Page 53: ...re interpreted as shown in Table 3 18 Table 3 18 2251A STA Response Description BIT EXPLANATION 1 lsb 2 and 3 Error number 1 to 5 in binary 2 3 4 1 External frequency standard 5 1 Reading ready 6 1 Error condition 7 1 Service requested SRQ 8 msb 1 Gate open Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com ...

Page 54: ...ilure 53 AC DC coupling Input A relay check failure 54 Input A low pass filter relay check failure 55 COM A relay check failure 56 X1 X10 Input B relay check failure 57 50 S 1MS Input B relay check failure 58 AC DC coupling Input B relay check failure NOTES 1 When Error 05 GPIB Syntax Entry Error occurs the erroneous command string will be correctly executed up to the error the rest will be handsh...

Page 55: ...lter AFE Enables Input A filter AHI Sets Input A input impedance to 1 Megohm ALI Sets Input A input impedance to 50 ohms AMN Selects Input A manual trigger mode ANS Sets Input A trigger to negative slope APS Sets Input A trigger to positive slope B0 Selects 10 MHz signal from backplane as reference frequency B1 Selects EXT STD INPUT as reference frequency BAC Selects Input B AC coupling BAD Disabl...

Page 56: ...signal on backplane connector P2 C 24 TTLTRG3 D4 Enable Gate out signal on backplane connector P2 A 26 TTLTRG4 D5 Enable Gate out signal on backplane connector P2 C 26 TTLTRG5 D6 Enable Gate out signal on backplane connector P2 A 27 TTLTRG6 D7 Enable Gate out signal on backplane connector P2 C 27 TTLTRG7 D8 Disable Gate output Default DD Disables Time Interval Delay DE Enables Time Interval Delay ...

Page 57: ...mode PH Selects Phase A relative to B measurement mode PW Selects Positive Pulse Width A measurement mode Q0 SRQ assertion UNCONDITIONALLY inhibited Q1 SRQ assertion upon error detection Q2 SRQ asserted for measurement ready Q3 SRQ asserted for measurement ready or error detection Q4 SRQ asserted for frequency standard change Q5 SRQ asserted for frequency standard change or error detection Q6 SRQ ...

Page 58: ...surement RF Reads total so far RGS Recalls VXIbus Processor Software issue number RGT Recalls Gate time RLA Recalls Input A trigger level RLB Recalls Input B trigger level RMn Recalls memory setting n Sets the 2251A to a previously stored configuration n 0 to 9 Note all stored settings are lost on powering down the 2251A 2251A configurations are stored by the SMn command code RMS Recalls master so...

Page 59: ...ontinuous auto trigger measurement Cancels S31 S31 Selects single shot auto trigger measurement S50 Selects Mean Amplitude measurement mode Cancels S51 or S52 S51 Selects Positive Peak amplitude measurement mode S52 Selects Negative Peak amplitude measurement mode S60 Selects Totalize A by B measurement mode when function code TA is written Cancels S61 S61 Selects Manual Totalize measurement mode ...

Page 60: ...v is 5 1 V to 5 1 V if X1 input attenuation is selected or 51 to 51 V if X10 input attenuation is selected Increments of 20 mV and 200 mV are permitted in the X1 and X10 input attenuation modes SLBv Sets Input B trigger level to v Volts The permitted range of values for v is 5 1 V to 5 1 V if X1 input attenuation is selected or 51 to 51 V if X10 input attenuation is selected Increments of 20 mV an...

Page 61: ...he relationship between resolution and gate time STB Query the Status Byte Register response is 0 to 113 Bit0 DDSB Bit4 Message Available Bit5 Event Status Bit Bit6 RQS MSS Bit T0 Selects continuous measurement mode T1 Selects single shot measurement mode T2 Starts Manual Totalize or triggers a measurement cycle when in T1 single shot mode T3 Stops Manual Totalize TA Selects Total A by B measureme...

Page 62: ...counter but not the absolute accuracy Absolute accuracies must be calculated from the expressions given in the Specifications section of this manual after finding the timebase errors that apply to the external frequency standard or CLK10 signals used by the counter 4 1 4 Required Test Equipment 4 1 4 1 Signal Generator 10 kHz to 1 3 GHz Racal Instruments 9087 4 1 4 2 Function Generator DC to 10 kH...

Page 63: ...S73 and S75 are 800 220 The expected results for S72 and S74 are S73 result 2 tolerance 20 40 and S75 result 2 tolerance 20 40 respectively For S77 and S78 tests it is necessary to input a 10MHz square wave signal with amplitude of a positive peak between 8V and 1 0V and a negative peak between 2V and 4V 6 A successful completion of the relays results in an output of CK 0000000000 0E000 Error Code...

Page 64: ... Connect the Function Generator to the 2251A as shown in Figure 4 1 Figure 4 1 Input A Low Frequency Sensitivity Test Configuration 4 1 6 2 Apply the frequencies given in Table 4 1 to the counter Verify that the 2251A gives a stable reading within the tolerances given at less than the signal levels given Frequency Signal level Resolution Tolerance 10 Hz 25 mV rms 8 1 Hz 5 kHz 25 mV rms 8 0 1 Hz 10...

Page 65: ...on to the values given in Table 4 2 and apply the frequencies given to the counters input A Verify that the 2251A gives a stable reading within the tolerances given at less than the signal level given Frequency Signal level Resolution Tolerance 200 MHz 50 mV rms 9 1 Hz 160 MHz 50 mV rms 9 1 Hz 100 MHz 25 mV rms 9 1 Hz 10 MHz 25 mV rms 8 1 Hz 100 kHz 25 mV rms 8 0 1 Hz Valid up to 30 C Table 4 2 In...

Page 66: ...LI 4 1 7 1 Connect the Function Generator to the 2251A as shown in Figure 4 3 Figure 4 3 Input B Low Frequency Sensitivity Test Configuration 4 1 7 2 Apply the frequencies given in Table 4 3 to the counters input B Verify that the 2251A gives a stable reading within the tolerances given at less than the signal level given Frequency Signal level Resolution Tolerance 10 Hz 25 mV rms 8 1 Hz 5 kHz 25 ...

Page 67: ...rement resolution to the values given in Table 4 4 and apply the frequencies given in Table 4 4 to the counters input B Verify that the 2251A gives a stable reading within the tolerances given at less than the signal levels given Frequency Signal level Resolution Tolerance 160 MHz 50 mV rms 9 1 Hz 100 MHz 25 mV rms 9 1 Hz 10 MHz 25 mV rms 8 1 Hz 100 kHz 25 mV rms 8 0 1 Hz Table 4 4 Input B Sensiti...

Page 68: ...al Generator to the counter as shown in Figure 4 5 Figure 4 5 Input C Test Configuration 4 1 8 1 3 Set the 2251A measurement resolution to the values given in Table 4 5 and apply the frequencies given in Table 4 5 to the counters input C Verify that the 2251A gives a stable reading within the tolerances given at less than the signal levels given Frequency Signal level Resolution Tolerance 40 MHz 1...

Page 69: ...z reference from the 2251A Command String IP TI ALI BCC 4 1 9 0 2 Connect the 2251A to the signal generator as shown in Figure 4 6 Set the signal generator to 10 MHz 0 dBm Figure 4 6 Time Interval A B Test Configuration 4 1 9 1 Set the counter input trigger slopes as shown in Table 4 6 and verify that the counters measurement result is as given in Table 4 6 Input A Input B Result Tolerance Slope S...

Page 70: ... external signal source 10 MHz Input Configure the external signal source to accept the 10MHz reference from the 2251A Command String IP TA ALI 4 1 10 2 Connect the 2251A to the signal generator as shown in Figure 4 7 Set the signal generator to 10 MHz 0 dBm Verify that the counters measurement result is 10000 1 Figure 4 7 Totalize A by B Test Configuration 4 1 10 3 Disconnect the test equipment A...

Page 71: ... measurement resolution to three digits Command String IP RA ALI SRS3 4 1 11 2 Connect the 2251A to the signal generator as shown in Figure 4 8 Set the signal generator to 50 MHz 100 mV rms Verify that the counters measurement result is 50000 10 Figure 4 8 Ratio A B Test Configuration 4 1 11 3 Disconnect the test equipment Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE w...

Page 72: ...lution to six digits Command String IP RC ALI SRS6 4 1 12 2 Connect the 2251A to the signal generator as shown in Figure 4 9 Set the signal generator to 50 MHz 100 mV rms Verify that the counters measurement result is 50000 10 Figure 4 9 Ratio C B Test Configuration 4 1 12 3 Disconnect the test equipment Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com ...

Page 73: ...stored trigger level Command code RLA and verify that it is 5 000 V 80 mV 4 1 13 4 Reverse the polarity of the DC input to the counter single shot autotrigger the counter and recall the stored trigger level value Verify that it is 5 000 V 80 mV 4 1 13 5 Set the 2251A to its home state Set the counter to DC input coupling for input B and enable special functions Command String IP BDC SFEBAU 4 1 13 ...

Page 74: ...e the polarity of the DC input to the counter trigger the measurement and recall the stored trigger level value Verify that it is 5 000 V 80 mV 4 1 13 8 Disconnect the test equipment Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com ...

Page 75: ...ase the signal generator output level until the counter gives a stable reading Note the signal generator output level 4 2 1 4 Enable the counters input A filter Command code AFE and verify that the 2251A no longer counts Increase the signal generator until the counter gives a stable reading Note the signal generator output level and verify that this level is approximately twice the level previousl...

Page 76: ...ignal generator output level until the counter gives a stable reading Note the signal generator output level 4 2 2 4 Enable the counters input A attenuator Command code AAE and verify that the 2251A no longer counts Increase the signal generator until the counter gives a stable reading Note the signal generator output level and verify that this level is approximately ten times the level previously...

Page 77: ... 10 mV Increase the signal generator output level until the counter gives a stable reading Note the signal generator output level 4 2 3 4 Enable the counters input B attenuator Command code BAE and verify that the 2251A no longer counts Increase the signal generator until the counter gives a stable reading Note the signal generator output level and verify that this level is approximately ten times...

Page 78: ... procedures to be carried out CAUTION The 2251A contains static sensitive devices Observe all Electrostatic Discharge precautions while the counter is disassembled 4 4 Reassembly Instructions 4 4 1 Align the bottom cover with the channels in the side extrusions of the counter and slide the cover along the channels 4 4 2 Secure the cover to the counter body with the thirteen screws obtained on the ...

Page 79: ... in the Home state 4 5 1 3 It is recommended that the counter is read repeatedly and the current measurement result displayed by the controller used while adjusting the counters input amplifiers to obtain a stable count 4 5 2 Input A Amplifier Setup Procedure 4 5 2 1 Set R12 fully counterclockwise and R10 to its midposition R10 and R12 are located on the counter PCB as shown in Figure 4 15 Figure ...

Page 80: ... GATE LED is flashing 4 5 2 6 Turn off the RF output of the signal generator 4 5 2 7 Set the counter resolution to eight digits Command code SRS8 4 5 2 8 Increase the signal generator output level to 13 mV rms 4 5 2 9 Adjust R12 slowly clockwise until the counter measurement result starts to become unstable Turn R12 slowly counterclockwise until the counter measurement result is stable value 100 M...

Page 81: ...Setup Configuration 4 5 3 4 Set the signal generator output to 100 MHz 3 0 mV rms 4 5 3 5 Adjust R11 to obtain a stable reading of 100 MHz 0 1 MHz Verify that the counters GATE LED is flashing 4 5 3 6 Turn off the RF output of the signal generator 4 5 3 7 Set the counter resolution to eight digits Command code SRS8 4 5 3 8 Increase the signal generator output level to 13 mV rms 4 5 3 9 Adjust R15 ...

Page 82: ... 5 4 3 Select Frequency C as the measurement function Command code FC 4 5 4 4 Set the signal generator output to 1 GHz 10 0 mV rms 4 5 4 5 Adjust R27 slowly clockwise until the GATE LED starts to flash and the measurement result is 1GHz 10 Hz 4 5 4 6 Turn off the signal generator output Reduce the signal generator output level to 9 0 mV rms 4 5 4 7 Turn on the signal generator output and verify th...

Page 83: ... Connect the master frequency standard 9480 FRS or equivalent to the EXT STD INPUT of the 2251 Frequency Counter 4 Connect the 2251A 10MHz UUT reference output to INPUT of the 2251A Figure 4 19 External Standard Output 5 Program the 2251 Frequency Counter as follows 1 Frequency Channel A 2 AC coupled 50 ohm input impedance 3 Auto Trigger 4 External Reference Input 5 10 S Gate Time 6 Enable math fu...

Page 84: ...tomatic Functions Commands The letters in all capital refer to the device dependent commands for the 2251A the automatic commands and their device dependent commands are COMMAND Parameter Set PW Positive Pulse Width defined as the time between the 50 amplitude point of the rising and falling edges of a waveform See Figure 5 1 NW Negative Pulse Width defined as the time between the 50 amplitude poi...

Page 85: ...sabled on Channel A the only channel on which it is available When in the automatic functions of Pulse Width and Rise Fall Time the signal being measured on the 2251A is on a single channel and the Common mode BCC is automatically enabled Channel A and B inputs are internally connected to allow the counter to minimize propagation delay and mismatch When in Common mode it is not possible to swap Ch...

Page 86: ...generated unless the 2251A has previously been masked by use of the Q n commands to do so BCS The 2251A will disable the Common mode and will expect to see a separate signal on the Channel B input BAC The 2251A will ignore this command as the coupling is controlled by Channel A due to the Common setting BMN The 2251A will ignore this command as the trigger control either automatic or manual is con...

Page 87: ...BPS The 2251A will change to Negative Width NW mode returning a header of NW Channel A will have negative slope enabled and Channel B will have positive slope enabled The default settings for a Negative Pulse Width NW command in addition to the above common settings are COMMAND Parameter Set TI Time Interval ANS Negative Slope Channel A BPS Positive Slope Channel B ADC Channel A DC Coupled The fol...

Page 88: ... to Fall Time FT with a header of FT Channels A and B will have a negative slop enabled BNS The 2251A will remain in the Rise Time RT mode with a header of RT and Channels A and B with positive slope enabled The default settings in addition to the above common settings when the Fall Time FT command is sent to the 2251A are COMMAND Parameter Set TI Time Interval ANS Negative Slope Channel A BNS Neg...

Page 89: ...een the two signals The Time Interval is then divided by the Period and the result multiplied by 360 to scale the answer for degrees Refer to Figure 5 3 Figure 5 3 Phase Measurement The default settings for the 2251A in the Phase mode are COMMAND Parameter Set PH RA PA TI The function is a sequential setting of functions which are not programmable or changeable by the user AMN Manual trigger Chann...

Page 90: ...asurement is being made on separate signals The Common input can be enabled if a single signal is to be characterized with the BCC command Summary To summarize the automatic functions are designed to reduce the user s setup time by programming the counter s functions and signal conditioning parameters for typical values appropriate to the measurement For example most pulse parameter measurements a...

Page 91: ... dependent on the frequency of the signal The slower the input signal the longer it takes for the auto trigger to complete its determination of the signal peaks and set the trigger threshold at the correct point The maximum amount of time is one 1 second per channel If auto trigger is enabled for both channels each channel will add to the measurement cycle time regardless of whether the channel is...

Page 92: ...ime interval to be measured Thus some idea of the time interval should be known in order to calculate the measurement time Meas Time 1 nS to 8x10 S Signal Dependent 7 Ratio Ratio measurement time is equivalent to the actual gate time The actual gate time always exceeds the programmed gate time by up to 2 periods of the slower input signal Thus the total measurement time is the sum of the programme...

Page 93: ... 1 mS Meas Time 1 002 S Measurement Cycle Processing time Trigger Time Meas Time Measurement Cycle 50 mS 500 mS 1 002 S Measurement Cycle 1 552 S NOTE Frequency period measurements do not require the enabling of auto trigger on both input channels Only the channel with the input signal needs to have auto trigger enabled This reduces the amount of overhead introduced by auto trigger Frequency perio...

Page 94: ...ime Measurement Cycle 50 mS 500 mS 500 mS 50 nS Measurement Cycle 1 05000005 S RATIO MEASUREMENTS Ratio Measurements involve frequency readings of two signals over a specified gate time EXAMPLE Signal A Frequency 2 MHz Period 0 5 FS Signal B Frequency 1 MHz Period 1 FS Programmed GateTime 100 mS Auto trigger Channel A 500 mS Auto trigger Channel B 500 mS Processing Time 50 mS Meas Time Programmed ...

Page 95: ...als is required in order to calculate the measurement time EXAMPLE Signal Frequency of Both channels 1 MHz Period 1 FS Auto trigger Channel A 500 mS Auto trigger Channel B 500 mS Processing Time 50 mS Expected Phase Difference 90E Phase Time Interval 360E Period Time Interval Phase Period 360E Time Interval 90E 1FS 360E Time Interval 250 nS Time Interval Meas Time 250 nS Ratio Meas Time Gate Time ...

Page 96: ...trigger This can be eliminated by using the manual trigger mode which does not add to the measurement cycle time The next major component is the gate time for frequency period and ratio measurements Up to 10 S can be added to the measurement cycle time if 10 digits of resolution is required Thus when considering measurement cycle time the user needs to consider the trade off between high resolutio...

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Page 98: ... assembly drawing parts list system wire list and wire list 407298 Virginia Panel Inc Series VP90 Interface Harness 407299 TTI Testron Inc Interface Harness TTI Receiver must be above chassis For more information on Racal Instruments complete line of Test Receiver Interface solutions contact your Sales Representative Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www art...

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Page 108: ... Number 1 Describe in detail the problem and symptoms you are having Please include all set up details such as input output levels frequencies waveform details etc 2 If problem is occurring when unit is in remote please list the program strings used and the controller type 3 Please give any additional information you feel would be beneficial in facilitating a faster repair time i e modifications e...

Page 109: ...lan Italy Tel 39 02 5750 1796 FAX 39 02 5750 1828 Racal Elektronik System GmbH Frankenforster Strasse 21 51427 Bergisch Gladbach 1 Germany Tel 49 2204 92220 FAX 49 2204 21491 Racal Australia Pty Ltd 3 Powells Road Brookvale NSW 2100 Australia Tel 61 2 9936 7000 FAX 61 2 9936 7036 Racal Electronics Pte Ltd 26 Ayer Rajah Crescent 04 06 07 Ayer Rajah Industrial Estate Singapore 0513 Tel 65 7792200 FA...

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