SNM-1001L
Satellite Modem
Installation and Operation Manual
Part Number MN/SNM1001L.IOM Revision 1
Errata A
Comtech EF Data Documentation Update
Subject:
Date:
Document:
Part Number:
Collating Instructions:
Comments:
The following changes provide updated information for page xii and Section 3.2.9. This
information will be incorporated into the next revision.
Change Specifics:
Changes to power consumption and fusing information
May 30, 2003
SNM-1001L Satellite Modem Installation and Operation Manual,
Rev. 1, dated March 17, 2003
MN/SNM1001L.EA1
Attach this page to page xii
ELECTRICAL SAFETY
The SNM-1001L Satellite Modem has been shown to comply with the following safety standard:
• EN 60950: Safety of Information Technology Equipment, including electrical business
machines.
The equipment is rated for operation over the range 85 to 264 volts AC. It has a maximum
power consumption of 55 watts without BUC power supply. Input power increases to 175W
with 100W, 24V BUC power supply at maximum load. Input power increases to 230W with
150W, 48V BUC power supply at maximum load.
FUSES
The SNM-1001L Satellite Modem is fitted with two fuses, one each for line and neutral
connections. These are contained within the body of the IEC power connector, behind a small
plastic flap.
• Use T3.15A, 20mm fuses.
For continued operator safety, always replace the fuses with the
IMPORTANT
correct type and rating.
\\tempefs1\cs_vol\tpubs\manuals\released_word\midas\snm1001l_r1\text\errata a.doc
1
3.2.9 AC Power Connector
A standard, detachable, non-locking, 3-prong power cord (IEC plug) supplies the
Alternating Current (AC) power to the modem. Observe the following:
Input Power
Input Voltage
Connector Type
Fuse Protection
55W maximum, 40W typical
without BUC power supply.
90 to 132 or 175 to 264 VAC
Unit switches ranges automatically
I.E.C
T3.15A 20 mm type fuses
Line and neutral fusing
\\tempefs1\cs_vol\tpubs\manuals\released_word\midas\snm1001l_r1\text\errata a.doc
2
SNM-1001L
Satellite Modem
Installation and Operation Manual
Part Number MN/SNM1001A.IOM
Comtech EF Data is an ISO 9001
Registered Company.
MULTIMEDIA INTEGRATED DIGITAL ACCESS SYSTEM
Copyright © Comtech EF Data, 2000, 2001, 2002. All rights
reserved. Printed in the USA.
Comtech EF Data, 2114 West 7th Street, Tempe,
Arizona 85281 USA, 480.333.2200 FAX: 480.333.2161
Revision 1
March 17, 2003
Customer Support
Contact the Comtech EF Data Customer Support Department for:
• Product support or training
• Information on upgrading or returning a product
• Reporting comments or suggestions concerning manuals
A Customer Support representative may be reached at:
Comtech EF Data
Attention: Customer Support Department
2114 West 7th Street
Tempe, Arizona 85281 USA
480.333.2200 (Main Comtech EF Data Number)
480.333.4357 (Customer Support Desk)
480.333.2161 FAX
or, E-Mail can be sent to the Customer Support Department at:
service@comtechefdata.com
Contact us via the web at www.comtechefdata.com
To return a Comtech EF Data product (in-warranty and out-of-warranty) for repair or
replacement:
1. Request a Return Material Authorization (RMA) number from the Comtech EF
Data Customer Support Department.
Be prepared to supply the Customer Support representative with the model
number, serial number, and a description of the problem.
2. To ensure that the product is not damaged during shipping, pack the product in
its original shipping carton/packaging.
3. Ship the product back to Comtech EF Data. (Shipping charges should be
prepaid.)
For more information regarding the warranty policies, see p.xviii.
.
i
Table of Contents
Customer Support........................................................................................................................................ i
About this Manual ...................................................................................................................................xiii
Electrical Safety ........................................................................................................................................xv
Telecommunications Terminal Equipment Directive...........................................................................xvi
EMC (Electromagnetic Compatibility).................................................................................................xvii
Warranty Policy .....................................................................................................................................xviii
CHAPTER 1. INTRODUCTION ............................................................................................. 1–1
1.1 Overview ...................................................................................................................................... 1–1
1.2 Options Summary ....................................................................................................................... 1–2
1.3 Comtech EF Data Part Numbers............................................................................................... 1–3
1.4 FAST Accessible Options ...........................................................................................................1–4
1.5 Compatibility............................................................................................................................... 1–5
1.6 Description of the Modulator..................................................................................................... 1–5
1.6.1 Overview............................................................................................................................... 1–5
1.6.2 Functional Description.......................................................................................................... 1–5
1.6.3 Description of Modulation Types ......................................................................................... 1–6
1.7 Description of the Demodulator................................................................................................. 1–9
1.7.1 Overview............................................................................................................................... 1–9
1.7.2 Functional Description........................................................................................................ 1–10
1.8 Description of Monitor & Control........................................................................................... 1–11
ii
SNM-1001L Satellite Modem Revision 1
Preface MN/SNM1001L.IOM
1.8.1 Overview............................................................................................................................. 1–11
1.8.2 Functional Description........................................................................................................ 1–12
1.9 Dimensional Envelope .............................................................................................................. 1–14
1.10 New in this Release.................................................................................................................... 1–15
CHAPTER 2. INSTALLATION/ UPGRADES ........................................................................2–1
2.1 Unpacking.................................................................................................................................... 2–1
2.2 Installation ................................................................................................................................... 2–2
2.2.1 Modem Installation (Optional).............................................................................................. 2–2
2.3 Software and Hardware Installation/Upgrades .......................................................................2–4
2.3.1 Reed-Solomon PCB .............................................................................................................. 2–4
2.3.2 Turbo Codec Installation....................................................................................................... 2–6
2.4 Data I/O Interface Connector (J8) Removal/Installation........................................................ 2–8
2.5 Hardware Upgrades.................................................................................................................... 2–9
2.5.1 Main PCB Firmware Chips................................................................................................... 2–9
2.6 Flash Upgrading........................................................................................................................2–11
2.6.1 Downloading Flash Updates from the Web ........................................................................ 2–12
CHAPTER 3. CONNECTOR PINOUTS.................................................................................3–1
3.1 Connector Overview ................................................................................................................... 3–1
3.2 Connector Description................................................................................................................ 3–3
3.2.1 Remote Connector and Pinouts (J6)...................................................................................... 3–3
3.2.2 Fault Connector and Pinouts (J7).......................................................................................... 3–4
3.2.3 Data I/O Interface Connector (J8)......................................................................................... 3–5
3.2.4 Auxiliary 1 Connector and Pinouts (J9)................................................................................ 3–9
3.2.5 Alarms Connector and Pinouts (J10) .................................................................................. 3–10
3.2.6 RF Output Connector (CP1) ...............................................................................................3–10
3.2.7 External Reference (CP2) ...................................................................................................3–10
3.2.8 RF Input Connector (CP3) .................................................................................................. 3–10
3.2.9 AC Power Connector .......................................................................................................... 3–11
3.2.10 Ground Connector (GND) ..................................................................................................3–11
CHAPTER 4. FRONT PANEL OPERATION......................................................................... 4–1
4.1 Front Panel .................................................................................................................................. 4–1
4.1.1 LED Indicators The 10 LEDs on the front panel indicate: • General modem summary faults
• Status • Alarms The indicators are defined in Table 4-1 as follows:............................................ 4–2
4.1.2 Front Panel Keypad............................................................................................................... 4–3
iii
SNM-1001L Satellite Modem Revision 1
Preface MN/SNM1001L.IOM
4.2 Menu System ...............................................................................................................................4–4
4.2.1 Revision Emulation............................................................................................................... 4–5
4.2.2 Menu Tree............................................................................................................................. 4–6
4.3 OPENING SCREEN................................................................................................................... 4–7
4.3.1 FUNCTION SELECT: CONFIGURATION........................................................................ 4–7
4.3.2 FUNCTION SELECT: MONITOR .................................................................................... 4–39
4.3.3 FUNCTION SELECT: FAULTS/ALARMS...................................................................... 4–46
4.3.4 FUNCTION SELECT: STORED FLTS/ALMS................................................................. 4–50
4.3.5 FUNCTION SELECT: REMOTE AUPC (CONDITIONAL)......................................... 4–55
4.3.6 FUNCTION SELECT: UTILITY....................................................................................... 4–58
FUNCTION SELECT:UTILITY: DEMODULATOR: RX TERMINAL LO ................................... 4–70
FUNCTION SELECT: UTILITY: INTERFACE: BUFFER PROGRAM ..................................... 4–76
FUNCTION SELECT: UTILITY: OUTDOOR UNIT: ODU FSK ADDRESS (CONDITIONAL) .4–
78
4.4 Custom Modem Defaults .......................................................................................................... 4–97
CHAPTER 5. MODEM TYPE............................................................................................... 5–1
5.1 Modem Type................................................................................................................................ 5–1
5.1.1 AUPC Operation (with Reed-Solomon) ............................................................................... 5–2
5.1.2 Closed Network Operation (Comtech EF Data) ...................................................................5–2
5.2 Custom Operation....................................................................................................................... 5–3
5.3 Reed-Solomon Modes .................................................................................................................5–4
CHAPTER 6. CLOCKING AND RX BUFFERING SETTINGS.............................................6–1
6.1 Clocking Options......................................................................................................................... 6–1
6.1.1 EIA-232, EIA-422, or V.35 Master/Master .......................................................................... 6–1
6.1.2 EIA-232, EIA-422, or V.35 Master/Slave ............................................................................6–1
6.2 Buffering ...................................................................................................................................... 6–2
6.2.1 Buffer Size ............................................................................................................................ 6–2
6.3 Doppler......................................................................................................................................... 6–7
6.4 Plesiochronous............................................................................................................................. 6–8
6.5 Frame/Multiframe Length ......................................................................................................... 6–9
6.5.1 Multiples of the Frame Length.............................................................................................. 6–9
6.5.2 Total Buffer Length ..............................................................................................................6–9
6.5.3 Converting Between Bits and Seconds ................................................................................. 6–9
CHAPTER 7. FORWARD ERROR CORRECTION (FEC) ....................................................7–1
iv
SNM-1001L Satellite Modem Revision 1
Preface MN/SNM1001L.IOM
7.1 Introduction................................................................................................................................. 7–1
7.2 Coding .......................................................................................................................................... 7–2
7.3 Turbo Product Codec (Hardware Option) ............................................................................... 7–2
7.3.1 Introduction...........................................................................................................................7–2
7.3.2 Mod/Demod Processing Delay .............................................................................................7–3
7.3.3 Comparison of all TPC Modes.............................................................................................. 7–4
7.4 Uncoded Operation (No FEC) ...................................................................................................7–5
CHAPTER 8. SYSTEM CHECKOUT..................................................................................... 8–1
8.1 System Checkout......................................................................................................................... 8–1
8.1.1 Interface Checkout ................................................................................................................ 8–2
8.1.2 Modulator Checkout .............................................................................................................8–3
8.1.3 Demodulator Checkout ........................................................................................................... 8–5
CHAPTER 9. FAULT ISOLATION ........................................................................................9–1
9.1 Fault Isolation.............................................................................................................................. 9–1
9.1.1 System Faults/Alarms ........................................................................................................... 9–2
9.1.2 Faults/Alarms Display........................................................................................................... 9–2
9.1.3 Faults/Alarms Analysis......................................................................................................... 9–2
CHAPTER 10. AUTOMATIC UPLINK POWER CONTROL.................................................10–1
10.1 AUPC ......................................................................................................................................... 10–1
10.2 Modes of AUPC Location......................................................................................................... 10–3
10.2.1 AUPC – Between Two Modems......................................................................................... 10–4
10.2.2 Self-Monitoring Local Modem AUPC Control .................................................................. 10–5
10.2.3 MUX Operation .................................................................................................................. 10–6
10.2.4 DEMUX Operation............................................................................................................. 10–6
10.2.5 Buffer Operation ................................................................................................................. 10–6
10.2.6 Loop Timing Operation ......................................................................................................10–7
10.2.7 Baseband Loopback Operation ........................................................................................... 10–7
10.2.8 Front Panel Operation ......................................................................................................... 10–7
CHAPTER 11. ASYMMETRICAL LOOP TIMING .................................................................11–1
11.1 Asymmetrical Loop Timing .....................................................................................................11–1
CHAPTER 12. FULLY ACCESIBLE SYSTEM TOPOLOGY (FAST)................................... 12–1
12.1 FAST System Theory................................................................................................................ 12–1
12.1.1 Implementation ................................................................................................................... 12–1
v
SNM-1001L Satellite Modem Revision 1
Preface MN/SNM1001L.IOM
12.2 Variable Data Rates .................................................................................................................. 12–5
CHAPTER 13. BUC FSK COMMUNICATIONS ....................................................................13–1
13.1 Introduction............................................................................................................................... 13–1
13.1.1 Transmission Interface........................................................................................................ 13–2
13.2 Message Structure..................................................................................................................... 13–2
13.2.1 Command Message Structure (IDU to ODU)..................................................................... 13–2
13.2.2 Response Message Structure (BUC to IDU)....................................................................... 13–3
13.3 Power Class................................................................................................................................ 13–3
CHAPTER 14. DECODER................................................................................................... 14–1
14.1 Decoder ...................................................................................................................................... 14–1
14.1.1 Sequential Decoder ............................................................................................................. 14–1
14.1.2 Viterbi Decoder................................................................................................................... 14–3
CHAPTER 15. REED-SOLOMON CODEC .........................................................................15–1
15.1 Reed-Solomon Codec ................................................................................................................ 15–1
15.1.1 Specifications...................................................................................................................... 15–2
15.1.2 Theory of Operation............................................................................................................ 15–2
15.1.3 Reed-Solomon Encoder ......................................................................................................15–3
15.1.4 Reed-Solomon Decoder ...................................................................................................... 15–5
APPENDIX A SPECIFICATION............................................................................................ A–1
A.1 Specifications .............................................................................................................................. A–1
A.2 Specification Summary.............................................................................................................. A–2
A.3 L-Band Modulator Specification Summary ............................................................................ A–3
A.4 Demodulator Specification Summary ......................................................................................A–4
A.5 L-Band Modulator Specifications............................................................................................. A–5
A.5.1 Digital Data Rate.................................................................................................................. A–5
A.5.2 Modulation and Encoding Types ......................................................................................... A–6
A.5.3 Scrambling Types ................................................................................................................A–7
A.5.4 Modulator Frequency Reference.......................................................................................... A–7
A.5.5 Modulator Spurious Emissions ............................................................................................ A–8
A.5.6 Modulator Phase Noise ........................................................................................................ A–8
A.5.7 Modulator IF Output Spectrum Shape ................................................................................. A–8
A.5.8 L-Band INMARSAT Spurious Emissions ........................................................................... A–8
A.5.9 Differential Encoder............................................................................................................. A–9
A.5.10 BPSK Bit Ordering .............................................................................................................. A–9
vi
SNM-1001L Satellite Modem Revision 1
Preface MN/SNM1001L.IOM
A.5.11 Interleaver (Reed-Solomon Codec)...................................................................................... A–9
A.5.12 Modulator Transmit Frequency (IF) .................................................................................... A–9
A.5.13 Transmit Frequency Change Time....................................................................................... A–9
A.5.14 Modulator Transmit IF Output Switch................................................................................. A–9
A.5.15 Modulator Transmit IF Power.............................................................................................. A–9
A.5.16 Modulator Power Offset..................................................................................................... A–10
A.5.17 Modulator I / Q Imbalance................................................................................................. A–10
A.5.18 Modulator Output Noise Floor........................................................................................... A–10
A.5.19 Modulator Spectrum Rotation............................................................................................ A–10
A.5.20 Modulator Output Return Loss .......................................................................................... A–10
A.5.21 L-Band ODU Reference Signal ......................................................................................... A–10
A.5.22 L-Band ODU Control and Monitor.................................................................................... A–10
A.5.23 Modulator Transmit IF Test Modes................................................................................... A–10
A.5.24 L-Band ODU Supply Voltage............................................................................................ A–11
A.5.25 ODU DC Current Sense..................................................................................................... A–11
A.6 Encoding ................................................................................................................................... A–11
A.6.1 BPSK Encoding ................................................................................................................. A–11
A.6.2 OQPSK Encoding .............................................................................................................. A–12
A.6.3 8-PSK Encoding................................................................................................................. A–12
A.7 L-Band Demodulator Specifications ...................................................................................... A–13
A.7.1 Digital Data Rate................................................................................................................ A–13
A.7.2 Demodulation and FEC Decoding Types .......................................................................... A–14
A.7.3 Descrambling Types .......................................................................................................... A–15
A.7.4 Differential Decoder .......................................................................................................... A–15
A.7.5 BPSK Bit Ordering ............................................................................................................ A–15
A.7.6 Deinterleaver (Reed-Solomon Codec) ............................................................................... A–15
A.7.7 Demodulator Spectrum Rotation ....................................................................................... A–15
A.7.8 Receive Frequency ............................................................................................................. A–16
A.7.9 Input Overload ...................................................................................................................A–16
A.7.10 Demodulator Input Return Loss......................................................................................... A–16
A.7.11 LNB Prime Power.............................................................................................................. A–16
A.7.12 LNB Band Control............................................................................................................. A–16
A.7.13 LNB Reference Signal ....................................................................................................... A–16
A.7.14 Receive Input Power (Composite) ..................................................................................... A–17
A.7.15 Demodulator Input Shape .................................................................................................. A–17
A.7.16 Receive Input Power (Desired Carrier).............................................................................. A–18
A.7.17 Demodulator Channel Spacing/Adjacent Carrier Performance ......................................... A–18
A.8 Bit Error Rate Performance ................................................................................................... A–19
A.8.1 Performance With Noise, Viterbi Decoder, and Closed Network ..................................... A–19
A.8.2 Performance with Noise, Viterbi Decoder, and Reed-Solomon (Optional).................... A–19
A.8.3 Performance With BPSK and {O}QPSK BER Performance ............................................ A–19
A.8.4 Performance with Noise Turbo Product Codec (Optional)................................................ A–20
A.8.5 Performance With Noise, 1544 kbps Sequential Decoder and Reed Solomon(Optional) A–20
A.8.6 Performance With Noise, 56 kbps Sequential Decoder (Optional) ................................... A–20
A.8.7 Performance With Noise, 1544 kbps Sequential Decoder (Optional) ............................... A–21
A.8.8 BER Threshold................................................................................................................... A–21
vii
SNM-1001L Satellite Modem Revision 1
Preface MN/SNM1001L.IOM
A.9 Acquisition Time ......................................................................................................................A–22
A.9.1 Receive Carrier Acquisition Range.................................................................................... A–23
A.9.2 Receive Carrier Reacquisition ........................................................................................... A–23
A.9.3 AGC Output ....................................................................................................................... A–23
A.9.4 Doppler Tracking Performance.......................................................................................... A–23
A.10 Interface Specifications........................................................................................................ A–24
A.10.1 TX Clock Switching Due to Failure of Selected Clock ..................................................... A–24
A.10.2 TX Clock Phase Adjustment.............................................................................................. A–24
A.10.3 TX Data Phase Adjustment................................................................................................ A–24
A.10.4 Transmit Clock Source....................................................................................................... A–24
A.10.5 Send Clock Timing Source ................................................................................................ A–24
A.10.6 Doppler/Plesiochronous Buffer Clock Source ................................................................... A–25
A.10.7 RX Clock Switching Due to Failure of Selected Clock..................................................... A–25
A.10.8 RX Clock Phase Adjustment.............................................................................................. A–25
A.10.9 RX Clock Jitter .................................................................................................................. A–25
A.10.10 RX Data Phase Adjustment............................................................................................ A–25
A.10.11 Buffer Centering ............................................................................................................ A–25
A.10.12 Receive Doppler/Plesiochronous Buffer Size................................................................ A–26
A.10.13 Switch Faults.................................................................................................................. A–26
A.11 Decoding................................................................................................................................ A–26
A.11.1 BPSK Decoding ................................................................................................................. A–26
A.11.2 QPSK Decoding................................................................................................................. A–26
A.11.3 Offset QPSK Decoding (Optional) .................................................................................... A–27
A.11.4 8-PSK Decoding ................................................................................................................ A–27
A.12 Terrestrial Interface Types ................................................................................................. A–28
A.12.1 EIA-232 Specification........................................................................................................ A–28
A.12.2 V.35 Specification V.10, V.11 Specification, Circuit Supported ...................................... A–29
A.12.3 EIA-449/EIA-422 Mil-188-114A Specification ................................................................ A–30
A.13 AUPC Specification (Optional)........................................................................................... A–31
A.13.1 AUPC Parameters .............................................................................................................. A–32
A.13.2 AUPC with Reed-Solomon Option.................................................................................... A–32
A.13.3 Turbo AUPC ...................................................................................................................... A–32
A.14 System Specifications........................................................................................................... A–33
A.14.1 Loopback Modes................................................................................................................ A–33
A.14.2 Test Modes......................................................................................................................... A–33
A.14.3 Remote Control.................................................................................................................. A–34
A.14.4 Modem Remote Address.................................................................................................... A–34
A.14.5 Monitored Signals.............................................................................................................. A–34
A.15 Stored Faults......................................................................................................................... A–35
A.16 Stored Configurations.......................................................................................................... A–35
A.17 Interoperability Modes ........................................................................................................ A–35
viii
SNM-1001L Satellite Modem Revision 1
Preface MN/SNM1001L.IOM
APPENDIX B. REMOTE CONTROL OPERATION.............................................................. B–1
B.1 General ............................................................................................................................................. B–1
B.2 Message Structure ........................................................................................................................... B–2
B.2.1 Start Character............................................................................................................................ B–2
B.2.2 Device Address .......................................................................................................................... B–2
B.2.3 Command/Response................................................................................................................... B–3
B.2.4 End Character............................................................................................................................. B–4
B.3 Configuration Commands/Responses............................................................................................B–5
B.3.1 Modulator Configuration Commands ........................................................................................ B–5
B.3.2 Demodulator Configuration Commands .................................................................................... B–7
B.3.3 Interface Configuration Commands ........................................................................................... B–9
B.3.4 System Configuration Commands............................................................................................ B–11
B.3.5 Automatic Uplink Power Control (AUPC) .............................................................................. B–12
B.4 Status Commands/Responses ....................................................................................................... B–14
B.4.1 Modulator Configuration Status............................................................................................... B–14
B.4.3 ODU Configuration Status................................................................................................ B–19
B.4.4 Fault Status........................................................................................................................ B–20
B.4.2 Error Performance .................................................................................................................... B–21
B.5 Stored Faults.................................................................................................................................. B–24
APPENDIX C. BURST MODE MODULATOR OPERATION .............................................. C–1
C.1 Burst Mode Modulator: Theory of Operation ........................................................................ C–1
C.1.1 Burst Mode........................................................................................................................... C–1
C.2 Burst Mode Modulator: Specifications .................................................................................... C–2
C.2.1 Digital Data Rate.................................................................................................................. C–2
C.2.2 Modulation and Encoding Types ......................................................................................... C–2
C.2.3 Scrambling Types ................................................................................................................C–3
C.2.4 Differential Encoder............................................................................................................. C–3
C.2.5 Transmit Frequency (IF) ...................................................................................................... C–3
C.2.6 Frequency Reference............................................................................................................ C–3
C.2.7 Transmit Frequency Change Time....................................................................................... C–3
C.2.8 Phase Noise.......................................................................................................................... C–4
C.2.9 Transmit IF Output Switch .................................................................................................. C–4
C.2.10 Transmit IF Power ...............................................................................................................C–4
C.2.11 Modulator Power Offset....................................................................................................... C–4
C.2.12 Modulated IF Output Shape ................................................................................................. C–4
C.2.13 Spurious Emissions ..............................................................................................................C–5
C.2.14 Modulator Phase Error ......................................................................................................... C–5
C.2.15 Transmit IF Test Modes ....................................................................................................... C–5
C.2.16 Modulator Spectrum Rotation.............................................................................................. C–5
C.2.17 Transmit Preamble ...............................................................................................................C–6
C.2.18 Transmit Packet ................................................................................................................... C–6
C.2.19 Transmit Postamble ............................................................................................................. C–6
ix
SNM-1001L Satellite Modem Revision 1
Preface MN/SNM1001L.IOM
C.3 Burst Mode Demodulator: Theory of Operation ....................................................................C–7
C.3.1 Burst Mode........................................................................................................................... C–7
C.4 Burst Mode Demodulator: Specifications ................................................................................ C–8
C.4.1 Digital Data Rate.................................................................................................................. C–8
C.4.2 Demodulation and FEC Decoding Types ............................................................................ C–8
C.4.3 Descrambling Types ............................................................................................................ C–8
C.4.4 Differential Decoder ............................................................................................................C–9
C.4.5 Demodulator Spectrum Rotation ......................................................................................... C–9
C.4.6 Receive Frequency (IF)........................................................................................................ C–9
C.4.7 Receive Input Power (Desired Carrier)................................................................................ C–9
C.4.8 Receive Input Power (Composite) ....................................................................................... C–9
C.4.9 IF Input Overload................................................................................................................. C–9
C.4.10 Demodulator IF Input Shape................................................................................................ C–9
C.4.11 Channel Spacing/Adjacent Carrier Performance ............................................................... C–10
C.4.12 Acquisition Time ............................................................................................................... C–10
C.4.13 Acquisition Probability ...................................................................................................... C–10
C.4.14 Receive IF Carrier Acquisition Range ............................................................................... C–10
C.4.15 Collision Recovery............................................................................................................. C–11
C.5 Burst Mode System - Specifications ....................................................................................... C–11
C.5.1 Loopback Modes................................................................................................................ C–11
C.5.2 Remote Control.................................................................................................................. C–12
C.5.3 Modem Remote Address.................................................................................................... C–12
C.5.4 Monitored Signals.............................................................................................................. C–12
C.5.5 Faults Monitored................................................................................................................ C–12
C.5.6 Stored Faults ...................................................................................................................... C–16
C.5.7 Stored Configurations ........................................................................................................ C–16
C.6 Burst Mode Specifications....................................................................................................... C–17
GLOSSARY G–1
INDEX i–1
x
SNM-1001L Satellite Modem Revision 1
Preface MN/SNM1001L.IOM
Figures
FIGURE 1-1. BLOCK DIAGRAM..........................................................................................................................1–2
FIGURE 1-2. DEMODULATOR BLOCK DIAGRAM ..........................................................................................1–9
FIGURE 1-3. M&C BLOCK DIAGRAM..............................................................................................................1–12
FIGURE 1-4. DIMENSIONAL ENVELOPE DRAWING ....................................................................................1–14
FIGURE 2-1. INSTALLATION OF THE OPTIONAL MOUNTING BRACKET KT/6228-1 ..............................2–3
FIGURE 2-2. REED-SOLOMON CODEC INSTALLATION................................................................................2–5
FIGURE 2-3. TURBO CODEC INSTALLATION..................................................................................................2–7
FOR RIBBON-CONFIGURED CONNECTOR FIGURE 2-4. DATA I/O CONNECTOR (J8)
REMOVAL/INSTALLATION.........................................................................................................................2–9
FIGURE 2-5. MAIN BOARD FIELD-CHANGEABLE CHIPS (SHOWN WITH OVERHEAD CARD
REMOVED) ...................................................................................................................................................2–10
FIGURE 3-1. REAR PANEL...................................................................................................................................3–1
FIGURE 4-1. FRONT PANEL VIEW .....................................................................................................................4–1
FIGURE 4-2. KEYPAD ...........................................................................................................................................4–3
FIGURE 4-3. MENU TREE.....................................................................................................................................4–6
FIGURE 4-4. RF LOOPBACK ..............................................................................................................................4–21
FIGURE 4-5. IF LOOPBACK ...............................................................................................................................4–22
FIGURE 4-6. BASEBAND LOOPBACK..............................................................................................................4–30
FIGURE 4-7. INTERFACE LOOPBACK .............................................................................................................4–31
FIGURE 6-1. EIA-422, EIA-232, OR V.35 MASTER/MASTER CLOCKING DIAGRAM..................................6–3
FIGURE 6-2. EIA-422, EIA-232, OR V.35 MASTER/SLAVE CLOCKING DIAGRAM.....................................6–4
FIGURE 6-3. CLOCK SLIP..................................................................................................................................6–5
FIGURE 6-4. DOPPLER SHIFT..............................................................................................................................6–6
FIGURE 7-1. VITERBI DECODER........................................................................................................................7–7
FIGURE 7-2. VITERBI DECODER AND REED-SOLOMON..............................................................................7–8
FIGURE 7-3. BPSK AND {O}QPSK BER PERFORMANCE...............................................................................7–9
FIGURE 7-4. TURBO PRODUCT CODEC..........................................................................................................7–10
FIGURE 7-5. SEQUENTIAL DECODER, REED-SOLOMON, AND 1544 KBPS .............................................7–11
FIGURE 7-6. SEQUENTIAL DECODER AND 56 KBPS ...................................................................................7–12
FIGURE 7-7. SEQUENTIAL DECODER AND 1544 KBPS................................................................................7–13
FIGURE 8-1. FAULT ISOLATION TEST SETUP.................................................................................................8–2
FIGURE 8-2. TYPICAL OUTPUT SPECTRUM ...................................................................................................8–5
FIGURE 8-3. TYPICAL EYE CONSTELLATIONS..............................................................................................8–6
FIGURE 10-1. AUPC BLOCK DIAGRAM ..........................................................................................................10–2
FIGURE 11-1. TRANSMIT SECTION OF THE ASYMMETRICAL LOOP TIMING BLOCK DIAGRAM.....11–2
FIGURE 11-2. RECEIVE SECTION OF THE ASYMMETRICAL LOOP TIMING BLOCK DIAGRAM ........11–3
FIGURE 14-1. SEQUENTIAL DECODER BLOCK DIAGRAM.........................................................................14–1
FIGURE 14-2. VITERBI DECODER BLOCK DIAGRAM..................................................................................14–3
FIGURE 15-1. REED-SOLOMON PCB (AS/5304-1)...........................................................................................15–1
FIGURE 15-2.REED-SOLOMON CODEC BLOCK DIAGRAM.........................................................................15–2
FIGURE 15-3. REED-SOLOMON ENCODER SECTION BLOCK DIAGRAM................................................15–3
FIGURE 15-4. REED-SOLOMON CODE PAGE FORMAT ................................................................................15–4
FIGURE 15-5. REED-SOLOMON DECODER SECTION BLOCK DIAGRAM................................................15–5
FIGURE A-1. CARRIER LEVEL VS SYMBOL RATE......................................................................................A–18
FIGURE C-1. SNM-1001L BURST MODE FAULT TREE ................................................................................ C–13
xi
SNM-1001L Satellite Modem Revision 1
Preface MN/SNM1001L.IOM
Tables
TABLE 1-1. FAST OPTIONS AND REQUIRED CONFIGURATIONS...............................................................1–4
TABLE 3-1. MODEM REAR PANEL CONNECTORS.........................................................................................3–2
TABLE 3-2. REMOTE CONNECTOR AND PINOUTS (J6).................................................................................3–3
TABLE 3-3. FAULT CONNECTOR AND PINOUTS (J7) ....................................................................................3–4
TABLE 3-4. 25-PIN D CONNECTOR PINOUTS ..................................................................................................3–6
TABLE 3-5. 34-PIN WINCHESTER CONNECTOR PINOUTS (V.35) ................................................................3–7
TABLE 3-6. 37-PIN CONNECTOR PINOUTS (OPTIONAL)...............................................................................3–8
TABLE 3-7. AUX 1 CONNECTOR AND PINOUTS (J9).....................................................................................3–9
TABLE 3-8. ALARMS CONNECTOR AND PINOUTS (J10).............................................................................3–10
TABLE 4-1. LED INDICATORS ............................................................................................................................4–2
TABLE 4-2. CUSTOM MODEM DEFAULTS.....................................................................................................4–97
TABLE 5-1. MODEM TYPE SELECTION ............................................................................................................5–1
TABLE 5-2. COMTECH EFD CLOSED NETWORK PARAMETER SETTINGS...............................................5–3
TABLE 5-3. REED-SOLOMON MODES...............................................................................................................5–4
TABLE 7-1. AVAILABLE TPC MODES ...............................................................................................................7–2
TABLE 7-2. TURBO PRODUCT CODING PROCESSING DELAY COMPARISON ..........................................7–3
TABLE 8-1. CONVERSION TO S/N AND EB/N0 CHART..................................................................................8–4
TABLE 10-1. SETTING AUPC PARAMETERS..................................................................................................10–3
TABLE A-1. SYSTEM SPECIFICATION SUMMARY........................................................................................A–2
TABLE A-2. L-BAND MODULATOR..................................................................................................................A–3
TABLE A-3. DEMODULATOR SPECIFICATION..............................................................................................A–4
TABLE A-4. MODULATOR DIGITAL DATA RATES.......................................................................................A–5
TABLE A-5. MODULATION AND ENCODING TYPES....................................................................................A–6
TABLE A-6. SCRAMBLING TYPES....................................................................................................................A–7
TABLE A-7. DEMODULATOR DIGITAL DATA RATE.................................................................................. A–13
TABLE A-8. L-BAND DEMODULATION AND FEC DECODING TYPES ....................................................A–14
TABLE A-9. DESCRAMBLING TYPES.............................................................................................................A–15
TABLE A-10. AUPC PARAMETERS .................................................................................................................A–32
xii
SNM-1001L Satellite Modem Revision 1
Preface MN/SNM1001L.IOM
About this Manual
This manual provides installation and operation information for the Comtech EF Data
SNM-1001A satellite modem. This is a technical document intended for earth station
engineers, technicians, and operators responsible for the operation and maintenance of
the SNM-1001A.
Related Documents
The following documents are referenced in this manual:
• INTELSAT Earth Station Standards 308, 309, and 310
Conventions and References
Cautions and Warnings
CAUTION
WARN ING
IMPORTANT
CAUTION indicates a hazardous situation that, if not avoided, may result in
minor or moderate injury. CAUTION may also be used to indicate other
unsafe practices or risks of property damage.
WARNING indicates a potentially hazardous situation that, if not avoided,
could result in death or serious injury.
IMPORTANT indicates a statement that is associated with the task
being performed. .
Examples of Multi-Hazard Formats
xiii
SNM-1001L Satellite Modem Revision 1
Preface MN/SNM1001L.IOM
Metric Conversion
Metric conversion information is located on the inside back cover of this manual. This
information is provided to assist the operator in cross-referencing English to Metric
conversions.
Recommended Standard Designations
Recommended Standard (RS) Designations have been superseded by the new designation
of the Electronic Industries Association (EIA). References to the old designations are
shown only when depicting actual text displayed on the screen of the unit (RS-232, RS485, etc.). All other references in the manual will be shown with the EIA designations
(EIA-232, EIA-485, etc.) only.
Trademarks
Product names mentioned in this manual may be trademarks or registered trademarks of
their respective companies and are hereby acknowledged.
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 EF Data Customer
Support Department.
xiv
SNM-1001L Satellite Modem Revision 1
Preface MN/SNM1001L.IOM
ELECTRICAL SAFETY
The SNM-1001L Satellite Modem has been shown to comply with the following safety standard:
• EN 60950: Safety of Information Technology Equipment, including electrical business
machines.
The equipment is rated for operation over the range 85 to 264 volts AC. It has a maximum
power consumption of 60 watts.
FUSES
The SNM-1001L Satellite Modem is fitted with two fuses, one each for line and neutral
connections. These are contained within the body of the IEC power connector, behind a small
plastic flap.
• For 230 volt AC operation, use T0.75A, 20mm fuses.
• For 115 volt AC operation, use T1.25A fuses, 20mm fuses.
IMPORTANT
Environmental
The SNM-1001L shall not be operated in an environment where the unit is exposed to
extremes of temperature outside the ambient range 0 to 50°C (32 to 122°F), precipitation,
condensation, or humid atmospheres above 95% RH, altitudes (un-pressurised) greater
than 2000 metres, excessive dust or vibration, flammable gases, corrosive or explosive
atmospheres.
Operation in vehicles or other transportable installations that are equipped to provide a
stable environment is permitted. If such vehicles do not provide a stable environment,
safety of the equipment to EN60950 may not be guaranteed.
For continued operator safety, always replace the fuses with the
correct type and rating.
xv
SNM-1001L Satellite Modem Revision 1
Preface MN/SNM1001L.IOM
Installation
The installation and connection to the line supply must be made in compliance to local or
national wiring codes and regulations.
The SNM-1001L is designed for connection to a power system that has separate ground,
line and neutral conductors. The equipment is not designed for connection to power
system that has no direct connection to ground.
The SNM-1001L is shipped with a line inlet cable suitable for use in the country of
operation. If it is necessary to replace this cable, ensure the replacement has an equivalent
specification. Examples of acceptable ratings for the cable include HAR, BASEC and
HOXXX-X. Examples of acceptable connector ratings include VDE, NF-USE, UL, CSA,
OVE, CEBEC, NEMKO, DEMKO, BS1636A, BSI, SETI, IMQ, KEMA-KEUR and
SEV.
International Symbols:
Symbol Definition Symbol Definition
~
Alternating Current
Fuse
Telecommunications Terminal Equipment Directive
In accordance with the Telecommunications Terminal Equipment Directive 91/263/EEC,
this equipment should not be directly connected to the Public Telecommunications
Network.
Protective Earth
Chassis Ground
xvi
SNM-1001L Satellite Modem Revision 1
Preface MN/SNM1001L.IOM
EMC (Electromagnetic Compatibility)
In accordance with European Directive 89/336/EEC, the SDM-300L3 Satellite Modem
has been shown, by independent testing, to comply with the following standards:
Emissions: EN 55022 Class B - Limits and methods of measurement of radio
interference characteristics of Information Technology Equipment.
(Also tested to FCC Part 15 Class B)
Immunity: EN 50082 Part 1 - Generic immunity standard, Part 1: Domestic,
commercial and light industrial environment.
Additionally, the SDM-300L3 has been shown to comply with the following standards:
EN 61000-3-2 Harmonic Currents Emission
EN 61000-3-3 Voltage Fluctuations and Flicker
EN 61000-4-2 ESD Immunity
EN 61000-4-4 EFT Burst Immunity
EN 61000-4-5 Surge Immunity
EN 61000-4-6 RF Conducted Immunity
EN 61000-4-8 Power frequency Magnetic Field Immunity
EN 61000-4-9 Pulse Magnetic Field Immunity
EN 61000-4-11 Voltage Dips, Interruptions, and Variations Immunity
EN 61000-4-13 Immunity to Harmonics
In order that the Modem continues to comply with these standards,
observe the following instructions:
IMPORTANT
• Connections to the transmit and receive IF ports (Type N and Type F, female,
connectors) should be made using a good quality coaxial cable - for example
RG58/U (50Ω or RG59/U (75Ω).
• All 'D' type connectors attached to the rear panel must have back-shells that
provide continuous metallic shielding. Cable with a continuous outer shield
(either foil or braid, or both) must be used, and the shield must be bonded to the
back-shell.
• The equipment must be operated with its cover on at all times. If it becomes
necessary to remove the cover, the user should ensure that the cover is correctly
re-fitted before normal operation commences.
xvii
SNM-1001L Satellite Modem Revision 1
Preface MN/SNM1001L.IOM
Warranty Policy
This Comtech EF Data product is warranted against defects in material and workmanship
for a period of two years from the date of shipment. During the warranty period, Comtech
EF Data will, at its option, repair or replace products that prove to be defective.
For equipment under warranty, the customer is responsible for freight to Comtech EF
Data and all related custom, taxes, tariffs, insurance, etc. Comtech EF Data is responsible
for the freight charges only for return of the equipment from the factory to the customer.
Comtech EF Data will return the equipment by the same method (i.e., Air, Express,
Surface) as the equipment was sent to Comtech EF Data.
Limitations of Warranty
The foregoing warranty shall not apply to defects resulting from improper installation or
maintenance, abuse, unauthorized modification, or operation outside of environmental
specifications for the product, or, for damages that occur due to improper repackaging of
equipment for return to Comtech EF Data.
No other warranty is expressed or implied. Comtech EF Data specifically disclaims the
implied warranties of merchantability and fitness for particular purpose.
Exclusive Remedies
The remedies provided herein are the buyer's sole and exclusive remedies. Comtech EF
Data shall not be liable for any direct, indirect, special, incidental, or consequential
damages, whether based on contract, tort, or any other legal theory.
Disclaimer
Comtech EF Data has reviewed this manual thoroughly in order that it will be an easy-touse guide to your equipment. All statements, technical information, and
recommendations in this manual and in any guides or related documents are believed
reliable, but the accuracy and completeness thereof are not guaranteed or warranted, and
they are not intended to be, nor should they be understood to be, representations or
warranties concerning the products described. Further, Comtech EF Data reserves the
right to make changes in the specifications of the products described in this manual at any
time without notice and without obligation to notify any person of such changes.
If you have any questions regarding your equipment or the information in this manual,
please contact the Comtech EF Data Customer Support Department.
xviii
Chapter 1. INTRODUCTION
SNM-1001L
Satellite
Modem
The SNM-1001L Satellite Modem is a dual function modem: it can operate in burst and
continuous mode.
1.1 Overview
• Burst mode operation: 19.2 kbps and/or 57.6 kbps, 1/2 rate QPSK
• 2.4 kbps to 5.0 Mbps Continuous Mode
• Automatic Uplink Power Control (AUPC)
• Reed-Solomon
• Turbo Product Coding
• Built-In Test
• BPSK, QPSK, Offset QPSK, and 8-PSK
• BUC FSK Communications
• Fully Accessible System Topology (FAST)
1–1
SNM-1001L Satellite Modem Revision 1
A
AGCA
A
A
A
A
A
Introduction MN/SNM1001L.IOM
Refer to Figure 1-1 for a system block diagram.
User
Data
UX 1
OC-TTL
Faults
Form C
Contacts
Remote
Port
C Or
Optional
DC
Prime
Power
J8
J9
J7
J10
J6
Power
Power
Supply
Supply
UX 1
Fault Relays
larm Rela ys
Remo te Port
Data
Data
Interface
Interface
UX 1
UX 1
M&C
M&C
Opt ODU
C Only
Opt ODU
Supply
Supply
Tx Data
Tx Clock
ST Clock
Rx Data
Rx Clock
I/Q
Sat Clock
Control / Status
SNM-1001L Satellite Modem
Figure 1-1. Block Diagram
1.2 Options Summary
Encoder /
Encoder /
Modulator
Modulator
Demodulator
Demodulator
/ Decoder
/ Decoder
Ref Osc
Ref Osc
Ext Ref
Tx IF
Note 1
Rx IF
Note 2
CP2
CP1
CP3
Notes:
1) Tx IF (L-Band only) Outputs a 10 MHz
2) Rx IF Outputs LNB V oltage and 10 MH z
Transmit
Transmit
RF Equipment
RF Equipment
LNB
LNB
Reference and Optional ODU Voltage.
Reference.
A summary of the available options for the unit is provided. Contact Comtech EF Data
Customer Support for upgrade information.
Option Description /Comment Availability Install Option
Single Data/Code Rate Yes FAST
Low Rate Variable
Full Rate Variable
≤ 512 kbps
≤ 5.0 Mbps
Offset QPSK Yes FAST
8-PSK Requires Viterbi, Reed-Solomon Codec.
Overhead card required for Open
Network.
TX/RX L-Band ± 0.02 ppm
L-Band Modem with high stability
reference.
TX only, L-Band ± 0.02 ppm
Hardware limited with high stability
reference.
RX only, L-Band ± 1.0 ppm
TX/RX L-Band ± 1.0 ppm
Hardware limited with 1 ppm reference Yes Factory
L-Band modem with 1 ppm reference Yes Factory
Sequential or Viterbi Codec Modem can be supplied with either:
Viterbi, Sequential
TX Reed-Solomon Codec Concatenates with Viterbi Yes User
RX Reed-Solomon Codec Concatenates with Viterbi Yes User
1–2
Yes FAST
Yes FAST
Yes User
Standard Factory
Yes Factory
Yes FAST
SNM-1001L Satellite Modem Revision 1
Introduction MN/SNM1001L.IOM
Option Description/Comment Availability Install Option
Turbo Codec Requires Reed-Solomon Codec
Asymmetrical Loop Timing (SCT) Yes FAST
AUPC (No ASYNC) Requires Reed-Solomon cards Yes User or FAST
37-Pin Female D Connector EIA-422/EIA-449 Interface and
25-Pin Female D Connector EIA-530 (RS-422), EIA-232 and V.35 Yes User
34-Pin Female V.35 “Winchester” Connector with V.35 Yes User
50-Pin Female D Connector for use
Overhead card.
Without
Primary Power: Auto-ranging AC 85 to
264 VAC
Primary Power: 48 VDC (Modem only,
No BUC)
ODU DC Power: 24V or 48V. Primary
input = AC Only
removal.
Mil-188-114
Includes EIA-422, EIA-232, and V.35
Use with redundancy switches
Yes Factory
Yes Factory
100W @ 24V
150W @ 48V
Yes User
Yes User
Yes User
Yes Factory
1.3 Comtech EF Data Part Numbers
Part No. Description Remarks
PL/9066-3 RX only IF 1.0 ppm Use with internal reference LNBs.
PL/9066-2 TX only IF 0.02 ppm Hardware limited version
PL/9066-1 TX/RX IF 0.02 ppm Full Duplex
PL/9066-5 TX/RX IF 1.0 ppm Full Duplex (No BUCs)
PL/5727-1 25-pin EIA-530 Interface
PL/6031-1 37-pin EIA-449 Interface
PL/6167-1 50-pin Interface No Overhead
PL/6032-1 34-pin Interface V.35
PL/6284 TX Reed-Solomon
PL/6285 RX Reed-Solomon
PL/9394-1 TX/RX Turbo
PS/AC65W01P01 90-264 VAC Modem PS Modem only
PS/DC-DC5V65W -48 VDC Modem PS Modem only
KT/9567-2 90 – 264 VAC, 100W
BUC P/S, 24V, CE Mark
KT/9567-3 90 – 264 VAC, 150 W
BUC P/S, 48 VDC
Hardware limited version.
24 VDC, 100W
AC BUC Power Supply
48 VDC 150 W
AC BUC Power Supply
1–3
SNM-1001L Satellite Modem Revision 1
Introduction MN/SNM1001L.IOM
1.4 FAST Accessible Options
Comtech EF Data FAST system allows immediate implementation of different options
through the user interface keypad. Some FAST options are available through the basic
platform unit, while others require that the unit be equipped with optional hardware or
that the hardware be installed in the field. Refer to Table 1-1 for a listing of possible
configurations.
The options available through the FAST architecture include:
• Single Data Rate • BUC FSK: DiSEQ
• Low Variable Data Rate
(up to 512 kbps)
• High Variable Data Rate
(up to 4.375 Mbps)
• Sequential Decoder
• Viterbi Decoder
• Asymmetrical Loop Timing
* Optional hardware required.
• OQPSK
• 8-PSK
• Offset QPSK
• Reed-Solomon COdec *
• AUPC
• Turbo Codec
Table 1-1. FAST Options and Required Configurations
Hardware
Basic Platform
SNM-1001L
FAST Option X X X X X X X
FAST Option with
Reed-Solomon
Option with Turbo
Hardware
Single Data rate
Low Variable Data
Rate
High Variable Data
Rate
X X
(Note 1)
X X
X
Sequential Decoder
X
(Note 1)
Viterbi Decoder
X
Asymmetrical Loop
Timing
BUC FSK: DiSEQ
Offset QPSK
8-PSK
Reed-Solomon
Codec (See Note 2)
AUPC
Turbo Codec (See
Note 2)
Notes:
1. The basic modem is shipped with either Sequential or Viterbi decoder.
2. Either Reed-Solomon or Turbo Codec is installed, not both.
1–4
SNM-1001L Satellite Modem Revision 1
Introduction MN/SNM1001L.IOM
1.5 Compatibility
The SNM-1001L is functionally compatible with many Comtech EF Data modems.
When properly configured, the unit will interoperate with the following Comtech EF
Data modems:
• CDM-550/550T (Turbo only) • SDM-650B
• CDM-600 (Open Network and Turbo only) • SDM-6000
• SDM-100/100A • SDM-8000
• SDM-300/300A • SDM-150A
• SNM-1010
1.6 Description of the Modulator
1.6.1 Overview
The modulator provides PSK modulated carriers within the 950 to 1750 MHz range. The
types of modulation that encode the transmitted baseband data from the interface PCB
are:
• BPSK
• QPSK
• Offset QPSK
• 8-PSK
1.6.2 Functional Description
The modulator is composed of eight basic subsections. These subsections are divided into
the baseband processing section and the RF section of the modulator. The modulator
controls all programmable functions on this module. Fault information from the
modulator is sent to the M&C. Refer to Chapter 9 for a list of reported faults. The major
modulator subsections are:
• Scrambler/Differential Encoder
• Convolutional Encoder
• Programmable Vector Rotation
• I/Q Nyquist Filters
• Modulator
• RF Synthesizer
• Output Amplifier
• Output Level Control
1–5
SNM-1001L Satellite Modem Revision 1
Introduction MN/SNM1001L.IOM
If the modem is so equipped, the optional Reed-Solomon PCB first processes the data.
The data is then sent to the scrambler for energy dispersal, and then to the differential
encoder. The differential encoder is a 2-bit encoder, which allows for resolution of two of
the four ambiguity states of the QPSK or OQPSK demodulator.
The data is sent to the convolutional encoder for encoding the baseband data. The code
rates 1/2, 3/4, 7/8, and 2/3 are based on the symbol rate range of 2.4 kbps to 2.5 Mbps.
For Viterbi codes, the convolutional encoder encodes the data at 1/2 rate. If the selected
code rate is 3/4, then 2 of every 6 symbols are punctured. For 3 bits in, there are 4
symbols out.
• For Sequential codes, the convolutional encoder generates the parity bits from the
input data stream, which allows for error correction at the far end of the link. The
rate of the encoder may be 1/2, 3/4, and 7/8.
For example, the 7/8 rate puts out 8 symbols for every 7 bits in. In {O}QPSK
mode, the data is split into two separate data streams to drive the I and Q channels
of the modulator.
The baseband processing for the SNM-1001L does not use the digital modulation.
Instead, the baseband Nyquist filtered I and Q signals pass through D/A converters to
drive an analog vector modulator.
The local oscillator input to the vector modulator is a single loop synthesizer
incorporating a Direct Digital Synthesis (DDS) chip to accommodate 100 Hz steps over
the range of 950 to 1750 MHz. The modulator output then passes through amplifiers and
AGC incorporating programmable output level control and switched low pass filters for
harmonic attenuation.
1.6.3 Description of Modulation Types
The modulation types for the modem include BPSK, QPSK, Offset QPSK, or 8-PSK.
The PSK data transmission encoding method uses the phase modulation technique. This
method varies the phase angle of the carrier wave to represent a different bit value for the
receiver. The higher levels of modulation are required for an operating range that has a
limited bandwidth.
The order of modulation is represented by mPSK, where “m” relates to the number of
discrete phase angles. Refer to the following list for a brief description of the modulation
types.
• BPSK: 2 discrete phase angles represent the 2 possible states of a symbol.
• Offset QPSK: 4 discrete phase angles represent the 4 possible states of a symbol.
1–6
Loading...