Degradation Due To Carrier Spacing | Mocomtech CDM-QX guide

CDM-Qx Satellite Modem	Revision 5
CnCPerformance Characterization	MN/CDMQx.IOM
Nominally, these effects are treated independently so it is possible to add them together
to estimate the total degradation. Initially, degradation due to carrier spacing is examined
to characterize the adjacent carrier performance. Next, the CnC ratio is evaluated to
estimate its impact. The symbol rate ratio of CnC carriers and the allowable carrier offset
are discussed followed by some CnC examples.
The rules for CnC operation are summarized below:
• Both earth stations share the same footprint so each sees both carriers
• CnC carriers are operated in pairs
• One outbound with multiple return carriers is not allowed
• Asymmetric data rates are allowed up to a symbol rate ratio of 3
• Minimum symbol rate for CnC is 128 ksps
• The CnC ratio is normally less than 10 dB
• CnC operates with modems not modulators only or demodulators only.

D.2 Degradation Due To Carrier Spacing

In satellite links, one of the impairments to estimate is the impact of carrier spacing on performance and allocate the degradation to the link budget. Data was taken using the CDM-Qx Modem, operating with Turbo coding, to measure Eb/No degradation 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 with noise to operate at a nominal or reference Eb/No corresponding to a BER ≈ 10-8and with no adjacent carrier present. A like- modulated adjacent carrier is then added and the Eb/No degradation recorded. The test is conducted with a single adjacent carrier as shown in Case A of Figure D-1, but this is equivalent to two equally spaced adjacent carriers on either side of the desired carrier, each 3 dB less than a single adjacent carrier as shown in Case B.

Adjacent

Carrier

Level Desired Adjacent

Carrier Carrier

R = +3 dB
A	Carrier
	Spacing

R = 0 dB Adjacent						Desired		Adjacent
				Carrier		Carrier		Carrier
				Carrier		Carrier		Carrier

					Carrier

B
B					Spacing
					Spacing

Figure D-1. Adjacent Carrier: A (As Tested) and B(As Plotted)

D–2

Image 244

Mocomtech CDM-QX Degradation Due To Carrier Spacing, Figure D-1. Adjacent Carrier a As Tested and BAs Plotted

Contents

CDM-Qx RevisionPage Errata a Acquisition rangePage Errata B Page Errata C Rx Rs n/k ENT IESS-310 network 219/201Page Errata D Tx Rs n/k ENT IESS-310 network 219/201Page Part Number MN/CDMQx.IOM Revision January 20,2007 Customer Support Table of Contents Chapter Functional Description External Connections Evolution of TPC in Comtech Products Comparison of all TPC Modes 11-1 Management Information Base MIB Files About this Manual Electrical Safety International Symbols CE Mark Warranty Policy CDM-Qx Satellite Modem Revision Preface MN/CDMQx.IOM Xii Introduction CDM-Qx/QxL Features Software Flash Upgrading DoubleTalk Carrier-in-CarrierVerification Data Interfaces Remote ControlTurbo Product Coding Assembly Description Major Assemblies Fast Options and Hardware Options Fast Fast Accessible Options Fast System TheoryImplementation Hardware Options Supporting Hardware and Software Band Compatibility CDM-Qx Satellite Modem Revision Introduction MN/CDMQx.IOM Installation Unpacking Optional Rear-Mounting Installation Bracket Mounting Installation of the Optional Mounting Brackets Configuration Select Internal if LoopConnect External Cables Observe the following Functional Description Page Modem Block Diagram Page Connections Front Panel LED Rear Panel Rear PanelPage Modem Rear Panel Connectors Name Ref. Desig Connector Type FunctionBNC IEC RF Output 75 or 50Ω 2 M&C 10/100BaseT Connector 3 485/232 ConnectorRemote Control Interface Connector Pin Assignments Use for 2-wire RS-485 operation Alarm Interface Connector Pin Assignments Alarms ConnectorPin # Signal Function Name Balanced G.703 Connector Tx/Rx Connector Unbalanced G.703 Tx/Rx ConnectorsBalanced G.703 Interface Connector Pin Assignments Pin # Signal Function Name Direction 7 RS-530 Data Interface Connector Pin # Generic Signal Description Direction RS-422 RSLvds RS-232 Circuit # Quad E1 Data Interface Connectors Xx6. Quad E1 Data Interface J1 Connector Pin Assignments RX and TX if Connectors AC Power ConnectorDC Power Connector AC Power Specifications Ground Connector This page is intentionally left blank Operation LED Front Panel LED IndicatorsColor Condition ENT Diamond Keypad Presently used on all UnitsCLR Left-Hand Display Area ModemsRight Hand Display Area TXF Redundancy MD MD Accessing the Display Area Spectrum AnalyzerRight-Hand Display Area RXS Principle Menu Tree Main Menu Config Monitor Test Info Save/Load Util ODU Opening ScreenComtech EF Data CDM-Qx Firmware Version ODU Config Config Remote Tx Rx Group Frame Interface Ref Mask ODU Config„Remote„Serial Config„Remote Remote ControlConfig„Remote„Serial„Interface Config„Remote„Serial„Baudrate Config„Remote„Serial„Interface„RS485 RS-485 Bus AddressConfig„Remote„Ethernet Config„Remote„Ethernet„Gateway Config„Remote„Ethernet„AddressConfig„Remote„Ethernet„MAC Config„Remote„Ethernet„SNMP Config„Remote„Ethernet„SNMP„Traps Config„Remote„Ethernet„SNMP„CommunitiesSnmp Trap Community , ENT comtech Trap Version ENT SNMPv1 SNMPv2Trap IP Addr#1 ENT Trap IP Addr#2 ENT Config„Tx Transmit Tx FEC Mod Code Data Freq On/Off Pwr Scram Clk Inv Txα Config„Tx„FEC TX FEC Type Config„Tx„Mod Modulation SchemeTx FEC Vit Vit+RS TCM+RS TPC Config„Tx„Code TX Code Rate Config„Tx„Data TX Data RateTx Code Rate 5/16 21/44 1/2 3/4 17/18 Tx Data Rate 05000.000kbps Sym02500.000ksps Config„Tx„Freq TX if Frequency Tx if Freq 1156.3456 MHz Config„Tx„On/Off Transmit ON/OFF Control Tx if Freq 1156.3456 MHz RF=14156.3456 ENTTx Output State On Off RxTxInhibit Common , ENT Tx Common Output State Off On Config„Tx„Pwr„Manual Manual Mode Config„Tx„Pwr Transmit Power Level ModeConfig„Tx„Pwr„AUPC Aupc Mode Config„Tx„Pwr„AUPC Target Eb/No Config„Tx„Pwr„AUPC MAX RangeConfig„Tx„Pwr„AUPC Alarm Config„Tx„Pwr„AUPC DEMOD-UNLOCK Config„Tx„Scram Scrambler Config„Tx„Pwr„Combined Combined Transmit PowerConfig„Tx„Clk TX Clocking Mode Config„Tx„Inv TX Inversion Functions Tx Inversion functions Spectrum Data Clock ,ENTTx Spectral Inversion Normal Inverted Tx Data Sense Config„Tx„Txα TX Roll-Off α factor Config„Rx ReceiveTx Roll-off 20% 35% ENT RxFEC Demod Code Data Freq Acq Descram Buf Inv Misc CnC Config„Rx„FEC RX FEC Type Rx FEC Vit Vit+RSTCM+RS Case Rules Comment Config„Rx„Demod Demodulation Scheme Config„Rx„Code RX Code RateDemodulation Bpsk Qpsk 8-PSK 16-QAM Rx Code Rate 5/16 21/44 1/2 3/4 7/8 17/18 Config„Rx„Data RX Data Rate Rx Data Rate 05000.000kbps Sym02500.000ksps Config„Rx„Freq RX Frequency Config„Rx„Acq Demod Acquisition RangeRx if Freq1156.3456 MHz RF=12156.3456 ENT Demod Acquisition Range Config„Rx„Buf RX Buffer Clock Source Config„Rx„Descram DescramblerENT Config„Rx„Inv RX Inversion Functions Config„Rx„Misc Rx Miscellaneous Config„Rx„Misc„Rxα RX Roll-Off α factor Config„Rx„Misc„EbNo Eb/No AlarmConfig„Rx„CnC CARRIER-IN-CARRIER→ Config„Rx„CnC„Mode CnC→ Mode of Operation Config„Rx„CnC„FrqOffs CnC Frequency OffsetPlease Check TX Power Level Please Wait Config„Rx„CnC„SrchDelay CnC Search Delay Config„Rx„CnC„ReAcq CnC RE-ACQUISITION TimeConfig„Group Grouping MOD/DEMOD Cards Config„Group„Modem Config„Group„Redundancy Config„Group„Redundancy„ConfigConfig„Group„Redundancy„Config „11 Config„Group„Redundancy„Config „12 Config„Group„Redundancy„Mode Config„Group„Redundancy„Mode„ManualConfig„Frame Framing Mode Config„Frame„Unframed Unframed Edmac Mode Framing mix AUPC-OnlyAUPC+EDMAC Master Slave Config„Frame„D&I++ D&I++ Distant-end Base Address0240 Address This Slave Unit ENT Config„Interface Data Interface Interface RS422 V.35 RS232Hssi ASI G.703 QDI None RTS/CTS operation , ENT Loop,RTS Controls Tx Out HDB3 AMI T1 Line Length Feet 703 E1 Line Code HDB3 AMI , ENT HDB3 AMI Config„Ref Reference Oscillator Config„Mask MaskAlarm Mask Transmit Receive Reference BUC LNB ,ENT Frequency Reference Internal MHz ENT Tx Alarm Mask Tx-FIFO BPV Tx-AIS ENT Tx-FIFO Alarm ENT Active MaskedRx Alarm Mask AGC Eb/No Rx-AIS Buffer AGC Alarm BUC Alarm Reference AlarmLNB Alarm Config„ODU Outdoor Unit for L-Band Unit Only Config„ODU„BUC Block Upconverter BUCODU BUC LNB Config„ODU„BUC„M&C-FSK M&C FSK Config„ODU„BUC„M&C-FSK„Address FSK CommsConfig„ODU„BUC„M&C-FSK„Address FSK Address BUC M&C Config„ODU„BUC„M&C-FSK„Tx-On/Off FSK TX-ON/OFF Config„ODU„BUC„DC-Pwr BUC DC PowerConfig„ODU„BUC„10MHz BUC 10MHz Config„ODU„BUC„Alarm BUC Alarm Config„ODU„BUC„Delay BUC Delay BUC Current Alarm Upper Limit1200mABUC Current Alarm Lower Limit1200mA Power-On Delay Config„ODU„BUC„LO BUC LO Config„ODU„BUC„Mix BUC MIX Config„ODU„LNB„Voltage LNB Voltage Config„ODU„LNB LNBLNB DC Config„ODU„LNB„10MHz LNB 10MHz Config„ODU„LNB„Power-On/Off LNB POWER- ON/OFFConfig„ODU„LNB„Alarm LNB Alarm Config„ODU„LNB„LO LO Config„ODU„LNB„Mix MIXLNB Current Alarm Lower Limit 050mA ENT LNB Frequency Mix Monitor„Alarms Alarms Monitor„Alarms„Unit Unit Alarms Monitor„Alarms„Transmit Transmit Alarms Monitor„Alarms„Receive Receive AlarmsMonitor„Alarms„ODU Outdoor Unit Alarms Monitor„Rx-Params RECEIVE-PARAMETERS Monitor„Event-Log EVENT-LOG or Stored Events Monitor„Event-Log„View View Stored Events Log 023 30/11/02 Fault Demod Lock 3 ,ENTLog 024 30/11/97 Clear Demod Lock 3 ,ENT Monitor„Stats Link Statistics for grouped as modem only Link Statistics View Clear-All Config ENTMonitor„Stats„View View Link Statistics Monitor„Stats„Config Configure Stats Stats Logging Interval Disabled,ENTMonitor„Stats„Clear-All Clear ALL Stats Clear all Stored Stats? No Yes Monitor„AUPC Monitor AUPCfor grouped as modem only Monitor„CnC Monitor CARRIER-IN-CARRIER CnC Monitor„ODU Monitor ODU for L-Band Unit only ODU LNB Mode Norm if 2 Dig 2 I/O 2 RF Tx-CW Tx1-0 ENT Test Mode Bist ENT Spec-AnalyzerTest TX-CW Norm If Loop Dig Loop RF LoopTX-1,0 Bist BERT-Config BERT-Mon BERT-Control ENT Bert Config Tx=ON Rx=ON Tx-Pat=2047 Rx-Pat=2047Bert Monitor Errs=0000253 BER=8.5E-07 Bert Control 10E-3Err=OFF Restart=NO SyncThres=256 Mode Config Spectrum Analyzer ModeConfig Spectrum Analyzer CenterFreq Span Spectrum Analyzer If Loopback Info Information Info„Rem Remote Control InformationInfo Rem Tx Rx Buffer Frame Interface Mask Ref ID Tx 1140.000 05000.000 TUR 8P 17/18 S EXT -20.0 on N Info„Tx TX InformationTx C N N Info„Rx RX Information Rx 1140.000 05000.000 TUR 8P 17/18 D RX BUF +/-32k NRx C N N Demod Sweep Acquisition range Buffer Enabled Tx=Rx ENT Info„Buffer Buffer InformationInfo„Frame Framing and Edmac Information Info„Interface Interface Information Info„Mask Alarm Mask Information Info„Ref Frequency ReferenceInfo„ID Circuit Identification Character TST Message Save/Load„Save Save Configuration No YES Save/Load„Load Load Configuration New Config has been Loaded From LocationEmpty ENT Contains No Data! ENT Utility„RxBuffer Buffer Recenter Utility„Clock REAL-TIME ClockUtility RxBuffer Clock Ref ID Display Firmware Fast Real-Time Clock , ,ENT Time=120000 Date24/04/03 Utility„Ref Reference Adjust Warm-up delay ENTUtility„ID Circuit Identification Internal Freq Utility„Display Display Brightness Utility„Firmware Firmware Update Cpld to v1.x.x? No Yes ENT Current Active Image #1 Next Reboot Image #1 #2Programming Cpld Utility„FAST Fast Code Options Fast View Options ENT Redun Not Installed Edit 20 digit Fast Code 00000000000000000000 ENT Forward Error Correction Options Viterbi Decoding Summary ViterbiFor Against Reed-Solomon Outer Codec Closed Network Modes Concatenated R-S Coding Summary Trellis Coding PSK/TCM Coding Summary Turbo Product Codec Hardware Option Introduction Evolution of TPC in Comtech Products Turbo Product Coding processing delay comparison End-to-End Processing DelayAvailable TPC Modes Comparison of all TPC Modes Turbo Product Coding Summary Viterbi Decoding BER Viterbi with PSK/TCM Rate 2/3 Decoding, withWithout 219, 201 RS Outer Code CDM-Qx Satellite Modem Forward Error Correction Options Comtech Turbo Product Codec Rate 3/4 QPSK, 8-PSK 16-QAM Comtech Turbo Product Codec Rate 7/8 QPSK, 8-PSK 16-QAM Comtech Turbo Product Codec Rate 21/44 Bpsk and Rate 5/16 Bpsk Turbo BPSK/QPSK BER Page Edmac Channel Theory Of Operation M&C Connection Setup Summary This page is intentionally left blank Automatic Uplink Power Control Target Eb/No Setting Aupc ParametersMax Range Demod Unlock AlarmCompensation Rate Monitoring DoubleTalk Carrier-in-Carrier Page Transponder Utilization with and without CnC→ Page Redundancy CDM-Qx Satellite Modem Revision Redundancy MN/CDMQx.IOM 10-2 Management Ethernet Management Interface Protocols Web Server Http Interface Web Web Server Menu Tree Web Server Menu TreeLevel 11-4 11-5 11-6 11-7 Snmp Interface Management Information Base MIB Files Snmp Community Strings Snmp Traps Alarms and Faults SNMPv2 notifications Telnet Interface 11-11 11-12 Page Page Modulator FEC Power Spectral Density Referred to symbol rateComtech EF Data CDM-Qx Transmit Demodulator ViterbiPSK/TCM Codec Turbo Product Modulation HIGHER-ORDERCoding Automatic Uplink Power Control Future Hssi Data Rate Ranges Miscellaneous Framing Summary FutureFCC Page Ethernet FTP upload procedure Appendix B. Flash Upgrading Construction Sector CDM-Qx Satellite Modem Revision Flash Upgrading MN/CDMQx.IOM Appendix C. Remote Control RS-485 RS-232 Basic Protocol Packet Structure Start Of PacketController-to-target Example 0135/TRQ=70.2345CR Target-to-controller Instruction Code AddressSlot Address Instruction Code Qualifier ‘=’ code Target to Controller is used in two ways $ code target-to-controller is only used as follows Message Arguments Remote CommandsEnd Of Packet CDM-Qx Satellite Modem Revision Remote Control MN/CDMQx.IOM TX Remote Commands TCR= TCR?TCR TCR# TSI= TSI= TSI?TSI TSI# TSI$ TCK= TCK= TCK?TCK TCK# RFQ= RFQ= RFQ?RFQ RFQ# RFQ$ RMD= RMD= RMD?=BPSK RMD =QPSK RMD# RDR= RDR= RDR?RDR RDR# RSW= RSW= RSW?RSW RSW# EBA= EBA= EBA?EBA EBA# EBA$ ITF= ITF= ITF?ITF ITF# ESA= ESA= ESA?ESA ERF= TST= TST= TST?TST TST# AUP= AUP= AUP?AUP AUP# LBO= LBO= LBO?LBO LBO# Hssi HHC=HHC? HHC Applies to CST= CST?CST CST# TIM= TIM= TIM?TIM TIM# IRM= IRM = IRM?IRM IRM# FBU= FBU= FBU?FBU FBU# CSD= CSD?CSD CSD# Query Commands EID? Bytes UID? =Change in fault FLT? WHO? REB? CC is Fault Code numbers, as in FLT? Or Infor Code, which RNE= RNS=CR RSL? RX BERCRM? CDM? SWR? CFM?FRW? IMG= IMG= IMG?IMG IMG# ITP? Bulk Commands OGC= OGC= OGC?OGC OGC# BAD= Arguments For Command or Response to QueryBand Unit Only BOE= BCH=BCL= BUC LO BLO= BUC BUT?BPA? BSV? Parameter Instruction Type Code Qualifier LNB Power Control Band Unit Only Parameter Instruction Type Code Qualifier Parameter Command Instruction Type Code Qualifier BCT= BCT= BCT?BCT# BCT$ SPM= SPF=SPS= SPM= SPM? DNI= DNI= DNI? DNI# DNI$ DNI DTS= Parameter Instruction Type Code Qualifier Drop TimeslotApplies to Cards grouped As modem CDM-Qx Satellite Modem Revision Remote Control MN/CDMQx.IOM Performance Characterization Carrier-in-CarrierDescription Degradation Due To Carrier Spacing Figure D-1. Adjacent Carrier a As Tested and BAs Plotted Carrier Spacing For 20% RolloffDegradation ≤ 0.5 dB Carrier Spacing For 35% Rolloff PSK 3/4 Turbo, α = 35% Selecting The Adjacent Carrier Curve Figure D-5. Adjacent Carrier Cases Curve To Use In Figure D-2, Error Carrier-in-Carrier Ratio CnC RatioCase Desired Adjacent Carrier Found., or D-4 Figure D-7. CnC Ratio For Qpsk and 8-PSK CnC Carrier Offset Symbol Rate Ratio1st CnC Example Adjacent Carriers, CnC Ratio and Rain Fade DL Fade UL Fade Site a Site B Site a Site BComment Per Figure D Figure D-10. Link With Fading At Site a 2nd CnC Example CnC Ratio With Asymmetric Links Link parameters and results are summarized in the table Parameters Site a Site B Eb/No Degradation At Site a Parameter Due To Fade At 3rd CnC Example Asymmetric Link With Rain FadePer Figure D- Qpsk Conclusion Eb/No Degradation At Site B Parameter Due To Fade At Metric Conversions 480 333 2200 Phone 480 333 2161 FAX