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CDM-Qx Satellite Modem

Revision 6

CnCPerformance Characterization MN/CDMQx.IOM

The link parameters and results are summarized in the table:

Parameters

Site A

Site B

Satellite EIRP (dBW)

37

37

Satellite BOo (dB)

6

6

Satellite BOi (dB)

10

10

Satellite SFD (dbW/m

2

) -78

-78

Satellite G/T (dB/K)

0

0

E/S Antenna (meters)

4.5

2.4

Data Rate (kbps)

192

192

Carrier Spacing Factor

1.3

1.3

Conventional Link

8PSK 2/3 TCM

8PSK 2/3 TCM

Occupied BW1 for 2 Carriers (kHz)

274.6

274.6

% of Transponder Power

0.55

0.16

CnC Link

QPSK 3/4 Turbo QPSK

3/4

Turbo

Occupied BW2 for 2 Carriers (kHz)

166.4

166.4

% of Transponder Power

0.37

0.11

CnC Ratio (dB)

+5.3

-5.3

Expected Eb/No Degradation (dB)

-0.1

0.0

The link asymmetry has increased the CnC ratio at Site A to +5.3 dB. Yet this results in a
degradation of only 0.1 dB. This is a C-Band link so no additional change in signal level
is expected due to rain fade. The CnC ratio at Site B is -5.3 dB so no degradation is
expected.

What is done if the CnC ratio is 10 dB or more? In a C-Band link it is possible to tolerate
the additional impairment, but then the modem is operating with less margin. One
possibility to reduce the CnC ratio is to increase the amount of power transmitted from
the remote site with the smaller antenna. This is feasible in some instances where there
are higher power satellite transponders. If the installation is a new one, a larger, though
more expensive, antenna is possible at the remote site. This simultaneously decreases the
CnC ratio at the hub while increasing it at the remote site.

Another alternative is to reduce the modulation order and/or error correction code rate on
the receive side of the remote site. This decreases the power transmitted by the hub and
reduces its CnC ratio. The hub’s CnC ratio will decrease further if it is possible to
increase the modulation order or code rate at the hub. In the above example changing
from QPSK 3/4 to QPSK 1/2 helps reduce the power but requires additional 1.5 times
more bandwidth. The 1.2 dB Eb/No difference between rate 3/4 and 1/2 reduces the CnC
ratio at the hub.

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Содержание CDM-Qx

Страница 1: ...Manual Note This manual incorporates data for the CDM Qx and CDM QxL IMPORTANT NOTE The information contained in this document supersedes all previously published information regarding this product Pr...

Страница 2: ......

Страница 3: ...s manual incorporates data for the CDM Qx and CDM QxL Comtech EF Data is an ISO 9001 Registered Company Part Number MN CDMQx IOM Revision 6 June 12 2007 Copyright Comtech EF Data 2007 All rights reser...

Страница 4: ...This page is intentionally blank...

Страница 5: ...al Safety xiii Fuses xiii Environmental xiii Installation xiii Telecommunications Terminal Equipment Directive xiv CE Mark xiv Trademarks xiv Warranty Policy xv Limitations of Warranty xv Exclusive Re...

Страница 6: ...lect Internal IF Loop 2 4 2 5 Connect External Cables 2 4 CHAPTER 3 FUNCTIONAL DESCRIPTION 3 1 CHAPTER 4 EXTERNAL CONNECTIONS 4 1 4 1 Introduction 4 1 4 2 Front Panel 4 1 4 3 Rear Panel 4 3 4 4 Chassi...

Страница 7: ...7 1 5 Config Frame FRAMING MODE 5 31 5 7 1 6 Config Interface DATA INTERFACE 5 33 5 7 1 7 Config Ref REFERENCE OSCILLATOR 5 36 5 7 1 8 Config Mask MASK 5 37 5 7 1 9 Config ODU OUTDOOR UNIT for L Band...

Страница 8: ...CK 5 59 5 7 6 3 Utility Ref REFERENCE ADJUST 5 60 5 7 6 4 Utility ID CIRCUIT IDENTIFICATION 5 60 5 7 6 5 Utility Display DISPLAY BRIGHTNESS 5 60 5 7 6 6 Utility Firmware FIRMWARE 5 61 5 7 7 Utility FA...

Страница 9: ...1 1 11 1 Introduction 11 1 11 2 Ethernet Management Interface Protocols 11 1 11 3 Web Server HTTP Interface 11 2 11 3 1 Web Server Menu Tree 11 3 11 4 SNMP Interface 11 8 11 4 1 Management Information...

Страница 10: ...mote Commands C 12 C 5 3 Common Remote Commands for Tx or Rx or Modem C 16 C 5 4 Query Commands C 25 C 5 5 Bulk Commands C 34 C 5 6 BUC Commands C 36 C 5 7 LNB Commands C 38 C 5 8 Built in BERT comman...

Страница 11: ...signments 4 10 Table 4 8 Interface Specifications 4 12 Table 4 9 HSSI EIA 613 Interface Connector Pinout 4 13 Table 5 1 Front Panel LED Indicators 5 2 Table 5 2 Prinicpal Menu Tree 5 6 Table 6 1 Viter...

Страница 12: ...erbi Rate 3 4 and Rate 7 8 with 220 200 R S Outer Code 6 16 Figure 9 1 Transponder Utilization with and without CnC 9 3 Figure A 1 Power Spectral Density Chart A 2 Figure D 1 Adjacent Carrier A As Tes...

Страница 13: ...uct in warranty and out of warranty for repair or replacement Contact the Comtech EF Data Customer Support Department Be prepared to supply the Customer Support representative with the model number se...

Страница 14: ...M Qx Reporting Comments or Suggestions Concerning this Manual Comments and suggestions regarding the content and design of this manual will be appreciated To submit comments please contact the Comtech...

Страница 15: ...t connector behind a small plastic flap CDM Qx 70 140 For 115 and 230 VAC operation use 2 0A 20mm fuses CDM Qx L Band For 115 and 230 VAC operation use T3 15A 20mm fuses FOR CONTINUED OPERATOR SAFETY...

Страница 16: ...UL CSA OVE CEBEC NEMKO DEMKO BS1636A BSI SETI IMQ KEMA KEUR and SEV CAUTION The modulator and demodulator cards shall not be plugged in when the modem is powered on Damage to the cards can be the res...

Страница 17: ...buyer of the repaired or replaced parts Limitations of Warranty The warranty does not apply to any part of a product that has been installed altered repaired or misused in any way that in the opinion...

Страница 18: ...g those of merchantability and fitness for a particular purpose The buyer shall pass on to any purchaser lessee or other user of Comtech EF Data Corporation s products the aforementioned warranty and...

Страница 19: ...i channel modem with redundancy contained in a single rack unit 1RU chassis The Modem offers flexibility redundancy integration and performance with four slots configurable as modulators or demodulato...

Страница 20: ...with Reed Solomon o Trellis and Reed Solomon o Optional 2nd Generation Turbo Product Coding TPC IESS 315 compliant Fully Accessible System Topology FAST Asymmetric Loop Timing Common frequency referen...

Страница 21: ...nfiguration parameters on the selected Demodulator are temporarily changed to match those of the selected Modulator and an internal RF switch connects the modulator output to the demodulator input Whe...

Страница 22: ...8 1 Quad E1 G 703 Data Interface Module PL 10898 1 EIA 612 613 HSSI Interface PL 10416 1 AC Chassis 70 140 IF PL 10416 2 DC Chassis 70 140 IF PL 12798 1 AC Chassis L Band PL 12798 2 DC Chassis L Band...

Страница 23: ...s Comtech EF Data s FAST system allows immediate implementation of different options through the user interface keypad All FAST options are available through the basic platform unit 1 4 2 FAST System...

Страница 24: ...on technologies currently available and is now offered with a sufficient range of code rates and modulation types to optimize link performance under any conditions The second hardware option is the In...

Страница 25: ...digital interfaces The modem expands the capabilities into L Band frequencies Utilizing advanced technology and proprietary digital signal processing techniques the design eliminates analog circuitry...

Страница 26: ...CDM Qx Satellite Modem Revision 6 Introduction MN CDMQx IOM Notes 1 8...

Страница 27: ...l extend more than 1 inch into the container This can cause damage to the modem Unpack the modem as follows Step Procedure 1 Cut the tape at the top of the carton indicated by OPEN THIS END 2 Remove t...

Страница 28: ...at 2 HW 10 32SPLIT Washer 10 Split 2 HW 10 32HEXNUT Nut 10 Hex 2 FP 6138 1 Bracket Rear Support 4 HW 10 32x1 2RK Bolt 10 Rack Bracket The tools required for this installation are a medium Phillips scr...

Страница 29: ...There are no internal jumpers to configure All configuration is carried out entirely in software The unit should first be configured locally using the front panel keypad and display The unit will shi...

Страница 30: ...es occur please call the factory for assistance Observe the following If modulators and demodulators are to be used without grouping them as a modem a data interface cable is required to plug into eac...

Страница 31: ...data is fed to the transmit digital filters which perform spectral shaping on the data signals The resultant I and Q signals are then fed to the BPSK QPSK 8 PSK 16 QAM modulator The carrier is generat...

Страница 32: ...demodulators to be installed If configured as a single modem two plug in cards comprising a modulator and demodulator are required A Modulator card contains the transmit interface circuits the framer...

Страница 33: ...CDM Qx Satellite Modem Revision 6 Functional Description MN CDMQx IOM Figure 3 1 Modem Functional Block Diagram 3 3...

Страница 34: ..._______________ _______________________________________ _______________________________________ _______________________________________ _______________________________________ ________________________...

Страница 35: ...ont panel of the modem 4 2 Front Panel Earlier Version prior to June 2007 USB LED Indicators Keypad Display VFD Current Version as of June 2007 Figure 4 1 Front Panel Earlier and Current Versions The...

Страница 36: ...They have a positive click action which provides the user with tactile feedback As shown in Figure 4 1 versions of the CDM Qx manufactured prior to June 2007 feature a keypad mounted directly behind a...

Страница 37: ...uration 3 Modem 1 with G 703 T1 E1 Balanced DB 15 and Quad E1 Interface Module 1 4 Ports of E1 with D I 4 RJ 45 Figure 4 2 Rear Panel Notes 1 One interface per Modem i e Modulator and Demodulator card...

Страница 38: ...interface located in the modulator or demodulator Table 4 1 Modem Rear Panel Connectors Name Ref Desig Connector Type Function Configuration 1 Modem1 with G 703 T1 E1 Balanced DB 15 Modem2 with EIA 4...

Страница 39: ...5 Remote Interface 485 232 9 Pin D Male Remote Interface Slot 1 Mod Alarms 15 Pin Male Form C Alarms G 703 BNC Unbalanced G 703 Data Output incorrect slot for IO Slot 2 Demod Alarms 15 Pin Male Form C...

Страница 40: ...ement functions 4 4 3 485 232 Connector The 485 232 connectors are a 9 pin D type male DB9 M Access is provided to remote control ports of the modem using both RS 232 and RS 485 Table 4 2 Remote Contr...

Страница 41: ...r RX fault and Unit Fault are supported If a Modulator and Demodulator are vertically grouped together as a modem TX fault and the External carrier off pin will also be supported The receive I and Q d...

Страница 42: ...Pin Signal Function Name Direction 1 Drop Data Input DDI In 9 Drop Data Input DDI In 2 Ground GND 10 Not Used 3 Insert Data Output IDO Out 11 Insert Data Output IDO Out 4 Ground GND 12 Drop Data Outpu...

Страница 43: ...eneric Signal Description Direction RS 422 RS 530 LVDS V 35 RS 232 Circuit 2 TX Data A DTE to Modem SD A SD A BA 103 14 TX Data B DTE to Modem SD B SD B 103 24 TX Clock A DTE to Modem TT A SCTE A DA 1...

Страница 44: ...uipment The second purpose of the connector is to allow the user to provide a reference E1 input clock The user can then use this E1 clock input to drive the demodulator receive buffer See the section...

Страница 45: ...of the CDM Qx s Modulators or Demodulators It provides physical and electrical connection between the external terrestrial device and the internal circuitry of the modulator or demodulator By convent...

Страница 46: ...te Signal Characteristics The A terminal is positive with respect to the B Terminal for a binary 1 Mark or ON state Clock Data Relationship The data transitions occur during the OFF to ON transition o...

Страница 47: ...ilable CA 107 3 28 from DCE Receive Data RD 104 4 29 from DCE Loopback circuit C LC undefined 5 30 from DCE Not used Send Timing ST 114 6 31 from DCE Signal Ground SG 102 7 32 Ground DTE Available TA...

Страница 48: ...nd neutral fusing 20 mm type fuses IMPORTANT For continued operator safety always replace the fuses with the correct type and rating 4 6 DC Power Connector A standard 3 screw terminal block supplies t...

Страница 49: ...in slots and indicates which slot is currently being addressed To navigate between sides is as simple as selecting a slot if the curser is on the left side and being in the root menu on the left side...

Страница 50: ...the unit from the Monitor menu Receive Traffic Note This LED corresponds to the selected slot example RX Green The Unit is On Line and carrying traffic Off The Unit is Off Line standby forced by exter...

Страница 51: ...onfiguration data numbers at the current cursor position Occasionally they may be used to scroll through a number of choices at the current cursor position Most of the menus space permitting include a...

Страница 52: ...directly below it to form a modem The example indicates a configuration in the right hand slots when viewed from the back of the chassis grouped together to form a modem Selecting the slots is the sa...

Страница 53: ...alyzer The built in spectrum analyzer mode is available accessible via remote control front panel or web browser When it is active the selected demod will not respond to specific Rx front panel settin...

Страница 54: ...7 2 1 Monitor Alarms Select Transmit Receive Unit ODU 5 7 2 2 Monitor Rx Params Select Eb No BER F BUF RSL 5 7 2 3 Monitor Event Log Select View Clear All 5 7 2 4 Monitor Stats Select View Clear All C...

Страница 55: ...enu branch permits the user to fully configure the unit Monitor This menu branch permits the user to monitor the alarm status of the unit to view the log of stored events and to display the Receive Pa...

Страница 56: ...cy Frame This menu sub branch permits the user to define if the unit should operate in a transparent mode no framing or in a framed mode In the framed mode EDMAC an overhead of 5 is added to the rate...

Страница 57: ...the user will be further prompted to enter the bus address Selecting RS232 displays the following menu Config Remote Serial Interface RS485 RS 485 Bus Address However if either RS 485 mode is selecte...

Страница 58: ...rnet displays the following Ethernet Config ENT Gateway Address MAC SNMP Config Remote Ethernet Gateway Selecting Gateway displays the following submenu M C Ethernet IP Gateway 192 128 001 001 ENT Edi...

Страница 59: ...mmunities displays the following submenu SNMP Communities Read Write ENT Selecting Read displays the following submenu Read Community ENT public Selecting Write displays the following submenu Write Co...

Страница 60: ...cters are available with the exception of backslash ASCII code 92 and ASCII code 126 When the user has composed the string press ENTER All trailing spaces are removed from the Community string upon en...

Страница 61: ...nu permits the user to select the transmit frequency from 950 MHz to 1950 MHz in steps of 100Hz for L Band units or from 50 MHz to 90 MHz and from 100 MHz to 180 MHz for 70 140MHz units On Off This su...

Страница 62: ...twork 219 201 All possible choices are presented at all times If an option is not installed either Hardware or FAST or not valid the arrow keys will force the cursor to skip past the unavailable choic...

Страница 63: ...ert QDI mode these data rates are read only otherwise they are read write The data rate will be the sum of the tributary rates for all ports This also will show the calculated symbol rate and Nx64kbps...

Страница 64: ...s Rate 3 4 384 kbps to 20 Mbps TPC 16 QAM Rate 7 8 448 kbps to 20 Mbps No Important Note Where noted in the table above if EDMAC framing is employed the upper data rate will be reduced by 5 for data r...

Страница 65: ...ure But please be aware that if an external IF Loopback is attempted connecting an external cable from the Tx IF output to the Rx IF input then this will not work The Tx carrier cannot turn on until t...

Страница 66: ...then pressing ENTER DemodUnlock ENT Config Tx Pwr AUPC TARGET Eb No Remote Demod Target Eb No Default value is 3 0 dB and upper limit is 9 9 dB Edit the target Eb No of the remote demod using the and...

Страница 67: ...ions are Default On The appropriate scrambler type is automatically selected IESS 315 On This only applies when Turbo is installed and has been selected as the FEC type Off No scrambling If CnC is ena...

Страница 68: ...o be made in this mode If the demodulator loses lock or if there is no receive signal present the internal clock is substituted Note also that this mode will work even with asymmetric Rx and Tx data r...

Страница 69: ...tion Rate 1 2 Rate 3 4 etc The available choice of Code Rate will depend on both the FEC type and Demodulation selected Data Data Rate This submenu permits the user to select the receive data rate in...

Страница 70: ...lomon QPSK Rate 1 2 Now the user changes the demodulation type from QPSK to 16 QAM In this case Rate 1 2 is no longer a valid code rate and so it will be automatically changed to the nearest valid cod...

Страница 71: ...CODE RATE Rx Code Rate 5 16 21 44 1 2 2 3 3 4 7 8 17 18 All possible choices are presented at all times If an option is not installed either Hardware or FAST or valid the arrow keys will force the cur...

Страница 72: ...PSK Rate 2 3 232 7 kbps to 18 3 Mbps Yes see note below Rate 5 16 32 kbps to 3 1 Mbps BPSK Rate 21 44 32 kbps to 4 7 Mbps Rate 21 44 32 kbps to 9 5 Mbps Rate 3 4 32 kbps to 15 Mbps Yes see note below...

Страница 73: ...nty the demodulator will search over in order to find and lock to an incoming carrier Edit the value by selecting the digit to be edited using the arrow keys The value of the digit is then changed usi...

Страница 74: ...instered and overwrite this looped data External is a user provided E1 frequency balanced clock on J5 of the Quad E1 interface card When Disabled is selected the Plesiochronous Doppler buffer is disab...

Страница 75: ...ing the arrow keys then press ENTER Selecting Clock displays the following submenu Rx Clock Inversion Normal Inverted ENT Selecting Normal or Inverted using the arrow keys then press ENTER Config Rx M...

Страница 76: ...the CnC FrqOffs Frequency Offset This submenu permits the user to adjust the frequency offset for the CnC SrchDelay Search Delay This submenu permits the user to configure the search delay parameters...

Страница 77: ...anged using the arrow keys then pressing ENTER Config Rx CnC ReAcq CnC RE ACQUISITION TIME Edit the re acquisition time using the arrow keys then pressing ENTER 5 7 1 4 Config Group GROUPING MOD DEMOD...

Страница 78: ...k up device Config Group Redundancy Config Config Redundancy None 1 1 1 2 1 3 ENT Selecting None turns off redundancy Config Group Redundancy Config 1 1 Selecting the 1 1 entry configures 1 1 redundan...

Страница 79: ...5 Config Frame FRAMING MODE Framing requires a modulator demodulator pair grouped into a modem see Config Group Framing Mode Unframed EDMAC EDMAC 2 D I ENT Select Unframed EDMAC EDMAC 2 or D I using t...

Страница 80: ...nit which is local to the M C computer and which passes messages via the overhead to a distant end modem An EDMAC SLAVE is a unit that is not local to the M C computer which is at the distant end of a...

Страница 81: ...Ins CH TS ENT Select Drp CH TS to display the Tx Data rate Select Ins CH TS to display the Rx Data rate 5 7 1 6 Config Interface DATA INTERFACE Data interface for each card modulator or demodulator is...

Страница 82: ...following options are possible TA to CA Loop TA and CA are looped but TA does not control the ON OFF state of the carrier RR controls CA TA controls Tx Out TA controls the ON OFF state of the carrier...

Страница 83: ...of them displays the next submenu as follows where X is the tributary port number Port X Drop Insert LineCode Alarm ENT Selecting Drop displays the following submenu Port X Tx Trib Rate ENT Disabled...

Страница 84: ...ort X Bipolar Violation Active Masked ENT Default is Masked 5 7 1 7 Config Ref REFERENCE OSCILLATOR The modem can accept an externally supplied frequency reference using the BNC connector on the rear...

Страница 85: ...ing submenu Tx Alarm Mask Tx FIFO G 703 BPV Tx AIS ENT Select Tx FIFO G 703 BPV or Tx AIS using the arrow keys then press ENTER For each of the choices a submenu similar to the one shown below will be...

Страница 86: ...then press ENTER If the user selects Active then a unit fault will be generated whenever the unit sees 1 External Reference is selected 2 There is no signal activity at the external reference port If...

Страница 87: ...dow If the measured BUC current falls outside this window an alarm is generated Delay This menu permits the user to define the carrier on delay following a power up sequence LO This menu permits the u...

Страница 88: ...s using the arrow keys then press ENTER The valid range is from 01 to 15 Config ODU BUC M C FSK Tx On Off FSK TX ON OFF Selecting Tx On Off displays the following submenu BUC RF Output Select On or Of...

Страница 89: ...UC Current Alarm Lower limit by selecting the digit to be edited using the arrow keys The value of the digit is then changed using the arrow keys then pressing ENTER Config ODU BUC Delay BUC DELAY Sel...

Страница 90: ...ENTER Voltage Selects 13 or 18 Volts as the LNB power supply output voltage 10MHz This menu permits the user to turn the 10MHz frequency reference for the BUC ON or OFF Alarm This menu permits the use...

Страница 91: ...ent Alarm Upper Lower ENT Select Upper or Lower using the arrow keys then press ENTER Selecting Upper displays the following submenu LNB Current Alarm Upper Limit 200mA ENT The range of current is fro...

Страница 92: ...isplaying the RF frequency of the modem BUC combination If a value of 00000 is entered here the default then no RF frequency will be displayed on the Config Rx Freq menu Config ODU LNB Mix MIX Selecti...

Страница 93: ...he arrow keys then press ENTER Depending on the selection one of the following menus will be shown Monitor Alarms Unit UNIT ALARMS Unit Fault 12 Volt PSU is under voltage ENT This screen indicates if...

Страница 94: ...indicates that the buffer is emptying and 50 indicates that it is filling RSL Receive Signal Level A value in dBm indicating the input power of the desired carrier as seen by the demodulator If the si...

Страница 95: ...onal convention the date is shown in DAY MONTH YEAR format IMPORTANT 5 7 2 4 Monitor Stats LINK STATISTICS for grouped as modem only Selecting Stats displays the following submenu Link Statistics View...

Страница 96: ...equal to 16 0 dB the display will show 16 0 dB If AUPC is not enabled the values of maximum and average TPLI will both show Off Examples 08 0 13 5 2 5 1 8 means Minimum Eb No observed in the measurem...

Страница 97: ...No 14 0dB TX Power Increase 2 2dB The top line displays the value of Eb No of the demodulator at the distant end of the satellite link The Eb No displays Unlock if the remote demod is unlocked The bot...

Страница 98: ...ure If BUC FSK is enabled displays BUC ambient temperature in C SW If BUC FSK is enabled displays the M C software version of the BUC PLL If BUC FSK is enabled displays the fault status of the BUC PLL...

Страница 99: ...This test mode invokes two distinct loopbacks The first of these is the inward loop which takes data being received from the satellite direction and passes it directly to the modulator Simultaneously...

Страница 100: ...BERT Config displays BERT Config Tx ON Rx ON Tx Pat 2047 Rx Pat 2047 If the selected slot is Tx the Rx parameters are not selectable and vice versa Note the BERT generator resides at the Tx side while...

Страница 101: ...set the BERT monitor Rx side for a fresh start of BER measurement The SyncThres control is the synchronization loss threshold as defined a 256 256 bit errors counted in less than 1000 bits o data b lo...

Страница 102: ...e Mask Ref ID These screens display information on the current configuration of the unit Depending on the choice selected one of the following screens is displayed using the arrow keys then press ENTE...

Страница 103: ...off Using arrow keys displays the following information Tx C N N 35 Top line Reed Solomon code rates C Comtech 220 200 E EF Data 225 205 I IESS 310 219 201 Tx Clock Inversion N Normal I Inverted Tx Da...

Страница 104: ...I Inverted Rx Roll Off factor 20 20 roll off 35 35 roll off 5 7 4 4 Info Buffer BUFFER INFORMATION Buffer Enabled Tx Rx This displays if the buffer is enabled or disabled shows the exact clocking mode...

Страница 105: ...h alarms are currently masked If an alarm is not masked a blank is displayed in the relevant screen position 5 7 4 8 Info Ref FREQUENCY REFERENCE Frequency Reference Internal 10 MHz ENT This displays...

Страница 106: ...stored configuration the following screen is displayed Your Configuration has been Saved to Location 9 ENT Pressing ENTER or CLEAR takes the user back to the previous menu If however the selected loc...

Страница 107: ...ILITY UTILITY RxBuffer Clock Ref ID Display Firmware FAST Select RxBuffer Clock Ref ID Display Firmware or FAST using the arrow keys then press ENTER Depending on the selection the following submenus...

Страница 108: ...r CW and an exact center frequency of for example 1000 MHz 5 7 6 4 Utility ID CIRCUIT IDENTIFICATION Edit Circuit ID ENT 28 CHARACTER TST MESSAGE Edit the Circuit ID string using the and arrow keys On...

Страница 109: ...he user may select using the arrow keys and ENTER key to view information about the Bootrom the 2 images or the CPLD on the modulator or demodulator card Each image can be viewed as follows Image x Bu...

Страница 110: ...the modem Obtain the FAST code for the new option from Comtech EF Data FAST Select the module Base Slot1 Slot2 Slot3 Slot4 The Base refers to the base unit where you can view the redundancy option as...

Страница 111: ...the following menu displays FAST Code Rejected ENT or CLR Selecting Demo Mode displays FAST Demo Mode Off On 604669 seconds remain The Demo Mode allows the user to use all FAST options with limited ti...

Страница 112: ...CDM Qx Satellite Modem Revision 6 Front Panel Operation MN CDMQx IOM Notes 5 64...

Страница 113: ...SIMM modules that are field upgradeable The codec provides data rate capability up to 20 Mbps and code rates of Rate 5 16 BPSK Rate 21 44 BPSK QPSK Rate 3 4 and 7 8 QPSK 8 PSK and 16 QAM Rate 17 18 QP...

Страница 114: ...d BER performance very useful coding gain Higher coding gain possible with other methods Almost universally used with de facto standards for constraint length and coding polynomials Shortest decoding...

Страница 115: ...very low data rates this equates to several seconds making it highly unsuitable for voice applications Additionally the de interleaver frame synchronization method can add significantly to the time ta...

Страница 116: ...ransponders are no longer power limited but bandwidth limited In order to maximize transponder capacity 8 PSK was looked at as a method of reducing the occupied bandwidth of a carrier and adopted Qual...

Страница 117: ...becomes unusable This is considered to be a particularly advantageous characteristic in a fading environment Typically in QPSK 8 PSK and 16 QAM TPC modes the demod and decoder can remain synchronized...

Страница 118: ...ith TPC this increase in delay is very modest The table below shows for the Modem the processing delays for the major FEC types including the three TPC modes Table 6 5 Turbo Product Coding processing...

Страница 119: ...6 9 dB 6 5 dB 1 90 bits Hz 0 53 x bit rate 626 kHz 8 PSK Rate 2 3 TCM and R S IESS 310 6 5 dB 5 6 dB 6 9 dB 6 0 dB 1 82 bits Hz 0 56 x bit rate 666 kHz 8 PSK Rate Turbo 6 2 dB 5 7 dB 6 8 dB 6 3 dB 2...

Страница 120: ...20 more bandwidth efficient than the TCM case The additional advantages of Turbo lower delay performance during fades etc should also be considered Table 6 6 Turbo Product Coding Summary FOR AGAINST...

Страница 121: ...1E 6 1E 5 1E 4 1E 3 1E 2 1E 1 1 2 3 4 5 6 7 8 9 10 11 12 Eb No in dB Specification limit Rate 1 2 Coding Uncoded BPSK QPSK Typical Performance Specification limit Rate 3 4 Coding 1 2 3 4 5 6 7 8 9 10...

Страница 122: ...200 Outer Code Uncoded BPSK QPSK 1 2 3 4 5 6 7 8 9 10 11 12 BER Viterbi with concatenated RS 220 200 Outer Code Combined sync threshold demod and Viterbi Decoder Rate 1 2 Sync threshold Rate 3 4 Spec...

Страница 123: ...Eb No in dB Specification limit Rate 2 3 Coding and 219 201 RS Outer Code Uncoded BPSK QPSK Typical Performance Specification limit Rate 2 3 Coding 1 2 3 4 5 6 7 8 9 10 11 12 BER 8 PSK TCM Rate 2 3 D...

Страница 124: ...oded BPSK QPSK Rate 3 4 QPSK 8 PSK and 16 QAM 1 2 3 4 5 6 7 8 9 10 11 BER Spec limit Rate 3 4 16 QAM Spec limit Rate 3 4 8 PSK Spec limit Rate 3 4 QPSK OQPSK Typical performance Performance with CDM Q...

Страница 125: ...ded BPSK QPSK Comtech Turbo Product Codec Rate 7 8 QPSK 8 PSK and 16 QAM 1 2 3 4 5 6 7 8 9 10 11 12 BER Spec limit Rate 7 8 16 QAM Spec limit Rate 7 8 8 PSK Spec limit Rate 7 8 QPSK OQPSK Typical perf...

Страница 126: ...bo Product Codec Rate 1 2 QPSK Rate 17 18 QPSK and 8 PSK Uncoded BPSK QPSK 1 2 3 4 5 6 7 8 9 10 11 12 BER Spec limit Rate 17 18 8 PSK Spec limit Rate 17 18 QPSK OQPSK Spec limit Rate 1 2 QPSK OQPSK Ty...

Страница 127: ...E 5 1E 4 1E 3 1E 2 1E 1 1 2 3 4 5 6 7 8 9 10 11 12 Eb No in dB Uncoded BPSK QPSK Comtech Turbo Product Codec Rate 21 44 BPSK Rate 5 16 BPSK 1 2 3 4 5 6 7 8 9 10 11 12 BER Spec limit Rate 21 44 BPSK Sp...

Страница 128: ...n dB Specification limit Rate 3 4 Viterbi and 220 200 RS Outer Code Uncoded BPSK QPSK Typical Performance Specification limit Rate 7 8 Viterbi and 220 200 RS Outer Code 1 2 3 4 5 6 7 8 9 10 11 12 BER...

Страница 129: ...of each frame a 12 bit synchronization word is added This allows the demodulator to find and lock to the start of frame At regular intervals throughout the frame additional data bytes and flag bits a...

Страница 130: ...will identify it as being for a distant end unit Before the M C data can be successfully transmitted and received pairs of units must be split into EDMAC Masters and EDMAC Slaves Masters are local to...

Страница 131: ...tant end This should normally be set to the base 10 address 1 For example if the MASTER unit is set to 30 choose 31 for the distant end unit On the distant end unit Enable framing and EDMAC define the...

Страница 132: ...CDM Qx Satellite Modem Revision 6 EDMAC Channel MN CDMQx IOM This page is intentionally blank 7 4...

Страница 133: ...n must be used The remote modem constantly sends back information about the demodulator Eb No using reserved bytes in the overhead structure The local modem then compares this value of Eb No with a pr...

Страница 134: ...s point the user will be prompted to define four key parameters 8 2 1 Target Eb No This is the value of Eb No that the user desires to keep constant at the remote modem If the Eb No exceeds this value...

Страница 135: ...nsation Rate As with any closed loop control system the loop parameters must be chosen to ensure stability at all times Several features have been incorporated to ensure that the AUPC system does over...

Страница 136: ...16 0 dB will be displayed As long as framing is enabled the value will still be available even though AUPC may be disabled Also displayed is the current value of Tx power increase If EDMAC framing is...

Страница 137: ...or and demodulator must be grouped together for CnC to operate 3 The relative power level between the two carriers must be 10 dB of each other For optimal performance the carriers should be 7 dB of ea...

Страница 138: ...me as the Tx and CnC is turned on At this point both sides of the link should be locked and passing traffic normally Once the links have been configured such that the Eb No values with good weather co...

Страница 139: ...Carrier Operation MN CDMQx IOM Uplink Transponder A B Downlink Transponder A B Traditional FDMA System Without CnC Uplink Transponder A B Downlink Transponder A B CDM Qx System With CnC Figure 9 1 Tra...

Страница 140: ...__________________ _______________________________________ _______________________________________ _______________________________________ _______________________________________ _____________________...

Страница 141: ...viewed from the rear When modules grouped as modems are being configured as redundant the backup modem has to be located in the right hand column of slots with the modulator on top If a 1 1 modulator...

Страница 142: ..._________ _______________________________________ _______________________________________ _______________________________________ _______________________________________ ______________________________...

Страница 143: ...hernet Management Interface Protocols The modem 10 100BaseT Ethernet Management Interface supports three 3 different management protocols Web Server interface for complete product management SNMP with...

Страница 144: ...et Explorer 5 5 or higher By typing http xxx xxx xxx xxx where xxx xxx xxx xxx Base Modem IP address on your browser the Login prompt will appear HTTP Login Access Levels are defined as follows User L...

Страница 145: ...Web Server Menu Tree Table 11 1 Web Server Menu Tree Level 1 Level 2 Home Home Contact Support Admin Access Remote Config Mdm Quick View Unit Status Maint Unit Info IMPORTANT Please make sure that the...

Страница 146: ...the web page the CDM Qx has two Tx cards and two Rx cards one Tx and one Rx grouped as modem and the others are individual Tx and Rx In this page the Base is highlighted that means the current page t...

Страница 147: ...Clicking any of these icons highlights them as illustrated in the next example As shown both the MD and Config icons are highlighted In this case both the modulator and demodulator parameters are acc...

Страница 148: ...view the constellation of the demodulated signal as shown In this example the CDM Qx has four 4 Rx cards installed Clicking Base then Test allows the user to simultaneously view all the constellation...

Страница 149: ...analyzer feature in the CDM Qx allows the user to view the spectrum of the signal as shown When the spectrum analyzer feature is turned ON the selected demodulator will not be allowed to receive traff...

Страница 150: ...of a particular function A MIB file is a tree of nodes that is unique to a particular device There are three MIB files associated with the CDM Qx MIB File Name Description fw10874 2 mib ComtechEFData...

Страница 151: ...trings for SNMP access Read Community default public Write Community default private Trap Community default comtech 11 4 3 SNMP Traps The modem has the ability to send out SNMP traps when certain even...

Страница 152: ...xRxTrafficAlarmV2 1 3 6 1 4 1 6247 27 2 0 3 11 5 Telnet Interface The modem provides a Telnet interface for two primary functions Equipment M C via the standard equipment Remote Control protocol Equip...

Страница 153: ...r n for the messages coming from Telnet Server the multi line command response for example FRW Response will be displayed as one line with the latter lines overwrite the previous lines In order to vi...

Страница 154: ...CDM Qx Satellite Modem Revision 6 Ethernet Management Base Modem MN CDMQx IOM 11 12...

Страница 155: ...rd low stability internal reference Stability 0 06 ppm 0 to 50 o C 32 o to 122 o F Optional high stability internal reference Stability 0 06 ppm 0 to 50 o C 32 o to 122 o F standard reference for L Ba...

Страница 156: ...c operation Rx and Tx data rates do not need to be identical External Clock at transmit data rate External TX Carrier Off By TTL low signal or external contact closure hardware function automatically...

Страница 157: ...te that Reed Solomon increases acquisition time due to the additional time taken for the RS decoder to declare synchronization Clock tracking range 100 ppm min VITERBI BER performance met in the prese...

Страница 158: ...No typical value in parentheses 2 4 dB 2 1dB 2 6 dB 2 3dB 2 7 dB 2 4dB TURBO PRODUCT CODEC Rate 3 4 QPSK Rate 3 4 8 PSK Rate 3 4 16 QAM BER With two adjacent carriers each 7 dB higher than the desire...

Страница 159: ...10 6 BER 10 8 16 QAM Rate 3 4 Viterbi RS Guaranteed Eb No typical value in parentheses 8 1 dB 7 5 dB 8 6 dB 8 0 dB 16 QAM Rate 7 8 Viterbi RS Guaranteed Eb No typical value in parentheses 9 5 dB 9 0...

Страница 160: ...9 pin D sub female 2 ports per DB 9 EIA 612 613 HSSI EIA 612 EIA 613 Rates up to 20 Mbps 50 pin mini D SCSI II HSSI female Modem Alarms Present on all modules Relay outputs Tx Rx unit faults Demodulat...

Страница 161: ...32 kbps to 4 7 Mbps TPC QPSK Rate 21 44 32 kbps to 9 5 Mbps TPC QPSK Rate 3 4 32 kbps to 15 Mbps TPC QPSK Rate 7 8 32 kbps to 17 5 Mbps TPC QPSK Rate 17 18 32 kbps to 18 888 Mbps TPC 8 PSK Rate 3 4 2...

Страница 162: ...dressable multidrop 2 wire or 4 wire 10 100 BaseT Ethernet M C Software SATMAC software for control of local and distant units AC Consumption Depends on configuration 120 watts maximum for 70 140 250...

Страница 163: ...ad procedure 1 Identify the reflashable product firmware number and version for download The current base modem M C version can be viewed at the top level menu of the front panel display press CLR but...

Страница 164: ...n firmware release is provided If applicable one version prior to the current release is also available Be sure to identify and download the desired version The downloadable files are stored in two fo...

Страница 165: ...g bin d Type prompt then type hash to facilitate the file transfers 7 Transfer the files Type put c temp FW11245 bin bulk to begin the file transfers The destination bulk must be all lower case While...

Страница 166: ...CDM Qx Satellite Modem Revision 6 Flash Upgrading MN CDMQx IOM Notes B 4...

Страница 167: ...pendent differential mode twisted pairs each handling serial data in different directions It is assumed that there is a controller device a PC or dumb terminal which transmits data in a broadcast mode...

Страница 168: ...reception by a UART In this case the asynchronous character format is fixed at 8N1 The baud rate may vary between 1200 and 38 400 baud All data is transmitted in framed packets The controller is assum...

Страница 169: ...ers Example 0654 RSW 32 CR LF Explanations for each of the components of the packet follow C 4 1 Start Of Packet Controller to Target This is the character ASCII code 60 Target to Controller This is t...

Страница 170: ...played in its raw ASCII form Only upper case alphabetic characters may be used A Z ASCII codes 65 90 C 4 4 Instruction Code Qualifier This is a single character that further qualifies the preceding in...

Страница 171: ...no message arguments This indicates that there was an error in the message sent by the controller The code Target to Controller is only used as follows If the controller sends an instruction to set a...

Страница 172: ...ode will allow the user to access the Web server SNMP or Telnet C 4 5 Message Arguments Arguments are not required for all messages Arguments are ASCII codes for the characters 0 to 9 ASCII 48 to 57 p...

Страница 173: ...ssage ok Received ok but invalid arguments found Message ok but not permitted in current mode Message ok but unit is not in Remote mode Time out of an EDMAC pass through message Message ok but no card...

Страница 174: ...CDM Qx Satellite Modem Revision 6 Remote Control MN CDMQx IOM Notes C 8...

Страница 175: ...TFQ 0950 9872 TFQ TFQ TFQ TFQ TFQ TFQ TFQ TFQ TFQ xxxx xxxx see description arguments TX FEC Type TFT 1 byte value of 0 though 7 Command or Query TX FEC coding type where 0 Reserved 1 Viterbi 2 Viter...

Страница 176: ...te Command or Query TX Reed Solomon n k values where 0 Unframed closed network 220 200 1 EFD closed network 225 205 2 IESS 310 compatible operation 219 201 3 EDMAC mode closed 200 180 EDMAC only Notes...

Страница 177: ...4 OFF due to BUC warm up delay not a valid argument in a command format Example TXO 1 TX Carrier ON TXO TXO TXO TXO TXO TXO TXO TXO TXO x see description of arguments TX Power Level TPL 4 bytes Comman...

Страница 178: ...l Tx 0 Off 1 On TXC TXC TXC TXC TXC TXC TXC TXC TXC x see description of arguments TX roll off alpha factor TXA 1 byte Command or Query Tx roll off alpha factor 0 20 1 35 default TXA TXA TXA TXA TXA T...

Страница 179: ...n of arguments RX Demod Type RMD 1 byte value of 0 through 5 Command or Query RX Demodulator where 0 BPSK 1 QPSK 2 Reserved 3 8 PSK 4 16 QAM Turbo or Viterbi Reed Solomon 5 Reserved Depending on FEC t...

Страница 180: ...s Resolution 1 bps See Chapter 5 for valid rates Query ONLY if Interface Type is Quad Drop Insert ITF D Example RDR 02047 999 RDR RDR RDR RDR RDR RDR RDR RDR RDR xxxxx xxxx see description of argument...

Страница 181: ...s 6 16384 bits Example RBS 0 RBS RBS RBS RBS RBS RBS RBS RBS RBS x see description of arguments RX Buffer Clock Source BCS 1 byte value of 0 through 4 Command or Query RX buffer clock source where 0 I...

Страница 182: ...al HDB3 7 G 703 E1 Bal AMI 8 G 703 E1 Bal HDB3 9 HSSI A ASI B G 703 TI Unbal AMI C G 703 T1 Unbal B8ZS D Quad Drop Insert F None Query only All other codes are invalid Example ITF 1 V 35 ITF ITF ITF I...

Страница 183: ...e value of 0 through 6 Command or Query External Reference Frequency where 0 Internal external reference connector not used 1 External 1 MHz 2 External 2 MHz 3 External 5 MHz 4 External 10 MHz 5 Exter...

Страница 184: ...ments Local Remote Status LRS 1 byte value of 0 1 Command or Query Local Remote status where 0 Local 1 Serial Remote 3 Ethernet Remote Example LRS 1 Serial Remote LRS LRS LRS LRS LRS LRS x see descrip...

Страница 185: ...d or Query Used to set the IP Address and network prefix for the 10 100 BadeTX Ethernet management port in the format xxx xxx xxx xxx yy where yy is the network prefix 0 to 31 Example 010 006 030 001...

Страница 186: ...bytes of Insert information I 31 bytes defining Timeslot locations or channels T Insert type 0 reserved 1 reserved 2 E1 CCS 3 reserved Timeslot definition 0 Unused 1 9 for timeslots 1 9 A 10 B 11 C 1...

Страница 187: ...1 byte argument 0 to 9 Example CLD 4 retrieve unit configuration from location 4 CLD CLD CLD CLD CLD N A N A ReCenter Buffer RCB None Command only Forces the software to recenter the receive Plesiochr...

Страница 188: ...e statistics log Example CAS Note This command takes no arguments CAS CAS CAS CAS CAS N A N A Initialize Statistics Pointer ISP None Command only Resets internal pointer to allow RNS Queries to start...

Страница 189: ...ot 1 is the primary card to be backed up 2 slot 2 is the primary card to be backed up 3 slot 3 is the primary card to be backed up Note For 1 1 Modem use FBU 1 FBU FBU FBU FBU FBU FBU FBU FBU x see de...

Страница 190: ...max delay value in milliseconds Maximum allowable value is 330ms Syntax CSD xxx yyy Where xxx min yyy max Example 010 325 CSD CSD CSD CSD CSD CSD CSD CSD CSD xxx yyy see description of arguments CnC...

Страница 191: ...0 None 1 8 PSK 8 QAM 2 16 QAM 3 8 PSK 8 QAM 16 QAM f Spare for future use g Spare for future use h Turbo data rate S W option 0 None 1 up to 512Kbps 2 up to 2048Kbps 3 up to 5Mbps 4 up to 10Mbps 5 up...

Страница 192: ...pable of supporting also1 2 and 1 1 If a 2 capable of supporting 1 1 as well b CnC First Instance rate option 0 None 1 128 Kbps to 512Kbps 2 128Kbps to 1Mbps 3 128Kbps to 2 5Mbps 4 128Kbps to 5Mbps 5...

Страница 193: ...nthesizer Lock 07 AUPC Upper Limit Reached 09 AIS Detected on Incoming Data 0B Bipolar violation on G 703 Interface 0F TX EEPROM Checksum Error 12 Power supply fault 5 volts 13 Power supply fault 5 vo...

Страница 194: ...bx cy dz see description of arguments Remote Eb No Modem only N A 4 bytes Query only Returns the value of Eb No of the remote demod Responds 99 9 remote demod unlock Responds xx x if EDMAC is disable...

Страница 195: ...t 2 RX Traffic on slot 1 3 RX Traffic on slot 2 4 RX Traffic on slot 3 5 RX Traffic on slot 4 6 TX Traffic on slot 1 7 TX Traffic on slot 2 8 TX Traffic on slot 3 9 TX Traffic on slot 4 A ODU B Power...

Страница 196: ...added with zeros N A RNS RNS CR AA ABB BC CD Ddd mmyyhhmmss CR AA ABB BC CD Ddd mmyyhhmmss CR AA ABB BC CD Ddd mmyyhhmmss CR AA ABB BC CD Ddd mmyyhhmmss CR AA ABB BC CD Ddd mmyyhhmmss see description...

Страница 197: ...C Delay Monitor N A 7 bytes Query only When CnC is enabled and it s locked it monitors the delay of the interferer in microseconds Example 1 CDM 229 500 229 5 ms Example 2 CDM 999 999 not locked or Cn...

Страница 198: ...FW 11250 1 1 1 1 11 08 04 FW 11251 1 1 1 1 11 16 04 FW 11252 1 1 1 1 06 25 04 FW 11253 1 1 1 1 10 21 04 FW 11254 1 1 1 1 11 18 03 N A FRW FRW x x see description of arguments Software Image IMG 1 byte...

Страница 199: ...s unlocked Example RFO 002 3 2 3 kHz N A RFO RFO sxxx x see description of arguments Buffer Fill State N A 2 bytes Query only Unit returns the value of the buffer fill state between 1 to 99 Returns 00...

Страница 200: ...hhh hhh Tx Data Rate same as TDR i Tx Spectrum Inversion same as TSI j Tx Scrambler State same as TSC kk k Tx Power Level same as TPL l Tx Clock Source same as TCK m Tx Data Invert same as TDI n Tx Ca...

Страница 201: ...t only OGC see description of arguments OGC aa BUC Address same as BAD b BUC FSK comms enable same as BCE c BUC Power Control same as BPC Where n 0 to 9 d BUC 10 MHz Freq Ref Enable same as BFR Return...

Страница 202: ...f arguments L Band Unit only BCE 0 Disabled BCE 1 Enabled BCE Example BCE 0 Disabled BUC Power Control BPC 1 byte value of 0 1 Command or Query BPC BPC BPC x 0 Disable BUC DC Power BPC see description...

Страница 203: ...ower Level N A 4 bytes Query only N A BOL BOL xx x BUC output power level in the form xxx where xxx is the value in watts see description of arguments L Band Unit only Example BOL 08 3 BUC reports out...

Страница 204: ...V 43 6 BUC DC voltage is 43 6 volts Terminal Tx Frequency N A 10 bytes Query only N A TTF TTF xxxxx xxxx see description of arguments Terminal Tx Frequency where frequency BUC LO TFQ L Band Unit only...

Страница 205: ...ere xxxxxx is the LO frequency in the range of 3000 to 65000 MHz LLO LLO LLO xxxxxs LLO see description of arguments L Band Unit only LLO All 0 s 000000 disables this feature LLO s is the sign for the...

Страница 206: ...nate 8 Mil 188 9 2 15 1 A 2 20 1 B 2 23 1 BERT Restart Monitor applies to Rx card BRM 1 byte value of 1 only Command only BRM N A N A Restarts or resets the BERT monitor BRM BRM Example BRM 1 BRM BRM...

Страница 207: ...Instruction Code and qualifier Arguments for Command or Response to Query Description of arguments Response to Command Target to Controller Query Instruction Code and Qualifier Response to query Targ...

Страница 208: ...ed 1 9 for timeslots 1 9 A 10 B 11 C 12 D 13 V 31 L reserved set to 0 Example 123456789ABCDEFGHIJKLMNOPQRSTUV2123456789ABCDEFGHIJKLM NOPQRSTUV20 Drop channels 1 31 using timeslots 1 31 Same for Insert...

Страница 209: ...d to adjacent carriers cross polarization and rain fade and exhibit impairments when any of these become too great In addition CnC operates in an environment where Carriers intentionally occupy the sa...

Страница 210: ...n with decreasing carrier spacing to characterize performance in the presence of two equally spaced like modulated adjacent carriers This is done without CnC For testing the modem is initially set up...

Страница 211: ...Carrier Spacing is the distance between the centers of the desired and adjacent carriers divided by the symbol rate There are two sets of adjacent carrier plots representing operation with 20 and 35...

Страница 212: ...0 dB 3 dB 6 dB For Two Equally Space Carriers Each With Level Relative To Desired Eb No Degradation Versus Carrier Spacing 8 PSK 3 4 Turbo 35 1 4 1 2 1 0 0 8 0 6 0 4 0 2 0 0 0 80 1 00 1 20 1 40 1 60 C...

Страница 213: ...he way the adjacent carrier testing is conducted It shows a single adjacent carrier 3 dB higher than the desired carrier equivalent to two like modulated adjacent carriers on either side of the desire...

Страница 214: ...tio CnC Ratio The CnC Ratio represents the difference in power between the co located interfering carrier and the desired carrier in dB CnC Ratio Interferer Power Desired Carrier During CnC operation...

Страница 215: ...eference Eb No with no interfering carrier present and the Eb No reported by the modem at a given CnC ratio Figure D 7 plots the impact of CnC ratio on QPSK and 8 PSK constellations while Figure D 8 s...

Страница 216: ...tically For estimating the link parameters the CnC ratio is adjusted by 10 Log Symbol Rate Ratio If the symbol rate ratio is 2 0 then the narrower carrier has a 3 dB CnC ratio when the CnC carriers ha...

Страница 217: ...fect is felt at both sites as outlined in Figure D 10 which diagrams the worst case fade at Site A The interfering carrier at Site A is attenuated twice once due to the uplink and the second time due...

Страница 218: ...returning on the downlink back to Site A Since the carrier transmitted and then received at Site A is the interfering carrier this extra attenuation is much less of an issue because it makes the CnC...

Страница 219: ...margin A link with a negative CnC ratio is also acceptable because the interfering signal is below the desired signal An asymmetric C Band link is shown in Figure D 11 It has equal symbol rate carrie...

Страница 220: ...ted What is done if the CnC ratio is 10 dB or more In a C Band link it is possible to tolerate the additional impairment but then the modem is operating with less margin One possibility to reduce the...

Страница 221: ...mation but other factors influence performance such as noise increase and G T degradation at the receive site From the previous examples there are some characteristics worth summarizing At the same sy...

Страница 222: ...A dB CnC Ratio Site B 5 3 5 3 Uplink Fade Site B 3 Uplink Fade Site A 6 Faded CnC Site B 8 3 0 7 Eb No Degradation dB Site B Per Figure D 10 QPSK 0 0 0 1 D 10 Conclusion There are several conclusions...

Страница 223: ...3 1 609 x 103 1 609 1 mm 0 03937 1 kilometer 0 621 Temperature Conversions Units of Weight Unit Gram Ounce Avoirdupois Ounce Troy Pound Avoirdupois Pound Troy Kilogram 1 gram 0 03527 0 03215 0 002205...

Страница 224: ...2114 WEST 7TH STREET TEMPE ARIZONA 85281 USA 480 333 2200 PHONE 480 333 2161 FAX...

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