Theory of Operation
SDM-309B Satellite Modem
5-5–20
MN/U-SDM309B Rev. #
5.4.2 Reacquisition
Normally the modem sweeps full range of plus/minus 30 KHz during acquisition. The
time it takes to complete one full sweep cycle depends upon the symbol rate of the
demod as follows:
1. If the demod symbol rate is less than or equal to 112 KBPS the sweep time is:
sweep time (in seconds) = 8400/SR (symbol rate in KBPS)
2. If the demod symbol rate is greater that 112 KBPS but less than 257 KBPS the
sweep time is: sweep time (in seconds) = 4200/SR (symbol rate in KBPS)
3. If the demod symbol rate is greater than 256 KBPS the sweep time is: sweep
time (in seconds) = 2100/SR (symbol rate in KBPS)
After initial acquisition (decoder locked for at least three seconds), if the carrier is lost
(decoder becomes unlocked) the modem enters the reacquisition mode. During
reacquisition the sweep is limited to 10% of the nominal sweep range, around the last
known lock point. If reacquisition does not take place during the time set for
reacquisition (0 - 999 seconds) the modem will terminate the reacquisition mode and
begin sweeping the full range of plus/minus 30 KHz.
The reacquisition mode is intended to reduce the time for reacquisition at lower symbol
rates. The following guidelines should be applied when using the re-acquisition mode:
1. The time specified for re-acquisition must be multiples of 10% of the total
nominal sweep time. This will insure that the modem has time to sweep across
the lock point at least once prior to termination of the re-acquisition mode.
2. Add a little to the re-acquisition time to account for the anticipated outage.
EXAMPLE: Demod operating at 64 Kbps, an anticipated outage of 2 seconds. What
should be the minimum re-acquisition setting?
Sweep time = 8400/64 = 132 second (round fractions up). Ten percent of the total sweep
time is 13.2 seconds. Add 2 seconds to the minimum re-acquisition time for the
anticipated outage.
ANSWER = 15.2 seconds, round up for 16 seconds minimum.
The additional function for sweep reacquisition can be found in the Configuration menu
of the front panel. SWP_RACQ is the parameter used to set the minimum reacquisition
time as described above.
Содержание SDM-309B
Страница 7: ...Preface SDM 309B Satellite Modem iv Rev 0 This page is intentionally blank ...
Страница 13: ...Table of Contents SDM 309B Satellite Modem x Rev 0 This page is intentionally blank ...
Страница 16: ...SDM 309B Satellite Modem Introduction MN U SDM309B Rev 1 1 3 Figure 1 1 SDM 309B Modem ...
Страница 18: ...SDM 309B Satellite Modem Introduction MN U SDM309B Rev 1 1 5 Figure 1 3 Modular Construction ...
Страница 19: ...Introduction SDM 309B Satellite Modem 1 1 6 MN U SDM309B Rev Figure 1 4 SDM 309B Block Diagram ...
Страница 23: ...Introduction SDM 309B Satellite Modem 1 1 10 MN U SDM309B Rev Figure 1 5 Typical Bit Error Rate Performance ...
Страница 25: ...Introduction SDM 309B Satellite Modem 1 1 12 MN U SDM309B Rev ...
Страница 28: ...SDM 309B Satellite Modem Installation MN U SDM309B Rev 2 2 3 Figure 2 1 Rear Panel View ...
Страница 34: ...SDM 309B Satellite Modem Operation MN U SDM309B Rev 3 3 Figure 3 1 Front Panel View ...
Страница 47: ...Operation SDM 309B Satellite Modem 3 16 MN U SDM309B Rev Figure 3 2 Menu Tree ...
Страница 48: ...SDM 309B Satellite Modem Operation MN U SDM309B Rev 3 17 Figure 3 3 Menu Tree ...
Страница 49: ...Operation SDM 309B Satellite Modem 3 18 MN U SDM309B Rev Figure 3 4 Menu Tree ...
Страница 50: ...SDM 309B Satellite Modem Operation MN U SDM309B Rev 3 19 Figure 3 5 Menu Tree ...
Страница 51: ...Operation SDM 309B Satellite Modem 3 20 MN U SDM309B Rev Figure 3 6 Menu Tree ...
Страница 52: ...SDM 309B Satellite Modem Operation MN U SDM309B Rev 3 21 Figure 3 7 Menu Tree ...
Страница 53: ...Operation SDM 309B Satellite Modem 3 22 MN U SDM309B Rev Figure 3 8 IF Loopback ...
Страница 54: ...SDM 309B Satellite Modem Operation MN U SDM309B Rev 3 23 Figure 3 9 RF Loopback ...
Страница 55: ...Operation SDM 309B Satellite Modem 3 24 MN U SDM309B Rev Figure 3 10 Interface Loopback ...
Страница 56: ...SDM 309B Satellite Modem Operation MN U SDM309B Rev 3 25 Figure 3 11 Baseband Loopback ...
Страница 71: ...Operation SDM 309B Satellite Modem 3 40 MN U SDM309B Rev Figure 3 12 Menu Tree ...
Страница 72: ...SDM 309B Satellite Modem Operation MN U SDM309B Rev 3 41 Figure 3 13 Menu Tree ...
Страница 73: ...Operation SDM 309B Satellite Modem 3 42 MN U SDM309B Rev Figure 3 14 Menu Tree ...
Страница 74: ...SDM 309B Satellite Modem Operation MN U SDM309B Rev 3 43 Figure 3 15 Menu Tree ...
Страница 75: ...Operation SDM 309B Satellite Modem 3 44 MN U SDM309B Rev Figure 3 16 Menu Tree ...
Страница 76: ...SDM 309B Satellite Modem Operation MN U SDM309B Rev 3 45 Figure 3 17 Menu Tree ...
Страница 77: ...Operation SDM 309B Satellite Modem 3 46 MN U SDM309B Rev ...
Страница 80: ...SDM 309B Satellite Modem M C and Interfaces MN U SDM309B Rev 4 4 3 Figure 4 1 Monitor Control Card ...
Страница 86: ...SDM 309B Satellite Modem M C and Interfaces MN U SDM309B Rev 4 4 9 Figure 4 2 IBS Interface Module ...
Страница 87: ...M C and Interfaces SDM 309B Satellite Modem 4 4 10 MN U SDM309B Rev Figure 4 3 IBS Interface Block Diagram ...
Страница 88: ...SDM 309B Satellite Modem M C and Interfaces MN U SDM309B Rev 4 4 11 Figure 4 4 IBS Fault Tree ...
Страница 89: ...M C and Interfaces SDM 309B Satellite Modem 4 4 12 MN U SDM309B Rev Figure 4 5 Jumper Table ...
Страница 95: ...M C and Interfaces SDM 309B Satellite Modem 4 4 18 MN U SDM309B Rev Figure 4 6 IBS Break Out Panel ...
Страница 105: ...M C and Interfaces SDM 309B Satellite Modem 4 4 28 MN U SDM309B Rev Figure 4 8 Drop and Insert Channel Unit ...
Страница 106: ...SDM 309B Satellite Modem M C and Interfaces MN U SDM309B Rev 4 4 29 Figure 4 9 Drop and Insert Block Diagram ...
Страница 107: ...M C and Interfaces SDM 309B Satellite Modem 4 4 30 MN U SDM309B Rev Figure 4 10 Drop Insert Fault Tree ...
Страница 108: ...SDM 309B Satellite Modem M C and Interfaces MN U SDM309B Rev 4 4 31 Figure 4 11 Drop Insert Jumper Table ...
Страница 112: ...SDM 309B Satellite Modem M C and Interfaces MN U SDM309B Rev 4 4 35 Figure 4 12 Drop and Insert Break Out Panel ...
Страница 118: ...SDM 309B Satellite Modem M C and Interfaces MN U SDM309B Rev 4 4 41 Figure 4 13 Rear Panel Switch Diagram ...
Страница 120: ...SDM 309B Satellite Modem M C and Interfaces MN U SDM309B Rev 4 4 43 Figure 4 14 Drop and Insert Schematic Diagram ...
Страница 127: ...SDM 309B Satellite Modem Theory of Operation MN U SDM309B Rev 5 5 3 Figure 5 1 Modulator Card ...
Страница 128: ...Theory of Operation SDM 309B Satellite Modem 5 5 4 MN U SDM309B Rev Figure 5 2 Modulator Block Diagram ...
Страница 129: ...SDM 309B Satellite Modem Theory of Operation MN U SDM309B Rev 5 5 5 Figure 5 3 Modulator Output Spectral Occupancy ...
Страница 133: ...SDM 309B Satellite Modem Theory of Operation MN U SDM309B Rev 5 5 9 Figure 5 4 Viterbi Decoder AS 0701 ...
Страница 134: ...Theory of Operation SDM 309B Satellite Modem 5 5 10 MN U SDM309B Rev Figure 5 5 Viterbi Decoder AS 0949 ...
Страница 135: ...SDM 309B Satellite Modem Theory of Operation MN U SDM309B Rev 5 5 11 Figure 5 6 Viterbi Decoder AS 2133 ...
Страница 136: ...Theory of Operation SDM 309B Satellite Modem 5 5 12 MN U SDM309B Rev Figure 5 7 Viterbi Decoder Block Diagram ...
Страница 137: ...SDM 309B Satellite Modem Theory of Operation MN U SDM309B Rev 5 5 13 Figure 5 8 Typical Decoder BER Performance ...
Страница 141: ...SDM 309B Satellite Modem Theory of Operation MN U SDM309B Rev 5 5 17 Figure 5 9 Demodulator Card ...
Страница 142: ...Theory of Operation SDM 309B Satellite Modem 5 5 18 MN U SDM309B Rev Figure 5 10 Demodulator Block Diagram ...
Страница 148: ...SDM 309B Satellite Modem Maintenance MN U SDM309B Rev 6 6 3 Figure 6 1 Typical Output Spectrum ...
Страница 149: ...Maintenance SDM 309B Satellite Modem 6 6 4 MN U SDM309B Rev Figure 6 2 Output Spectrum With Noise ...
Страница 151: ...Maintenance SDM 309B Satellite Modem 6 6 6 MN U SDM309B Rev Figure 6 3 Typical Eye Patterns ...
Страница 152: ...SDM 309B Satellite Modem Maintenance MN U SDM309B Rev 6 6 7 Figure 6 4 Typical Eye Constellations ...
Страница 166: ...SDM 309B Satellite Modem Maintenance MN U SDM309B Rev 6 6 21 Figure 6 10 Rear View Without Cover ...
Страница 171: ...SDM 309B Satellite Modem Data Rates and Filters MN U SDM309B Rev A 3 Figure A 1 Modulator Filter Card Change ...
Страница 172: ...Data Rates and Filters SDM 309B Satellite Modem A 4 MN U SDM309B Rev Figure A 2 Demodulator Filter Card Change ...
Страница 173: ...SDM 309B Satellite Modem Data Rates and Filters MN U SDM309B Rev A 5 Figure A 3 Fixed Rate Modulator Filter ...
Страница 174: ...Data Rates and Filters SDM 309B Satellite Modem A 6 MN U SDM309B Rev Figure A 4 Fixed Rate Demodulator Filter ...
Страница 175: ...SDM 309B Satellite Modem Data Rates and Filters MN U SDM309B Rev A 7 Figure A 5 Variable Rate Modulator Filter ...
Страница 176: ...Data Rates and Filters SDM 309B Satellite Modem A 8 MN U SDM309B Rev Figure A 6 Variable Rate Demodulator Filter ...
Страница 177: ...SDM 309B Satellite Modem Data Rates and Filters MN U SDM309B Rev A 9 ...
Страница 207: ...Remote Control SDM 309B Satellite Modem B B 30 MN U SDM309B Rev Where x xx is the software version number ...
Страница 211: ...External Channel Unit SDM 309B Satellite Modem C C 4 MN U SDM309B Rev Figure C 2 System Interconnect Diagram ...
Страница 212: ...SDM 309B Satellite Modem External Channel Unit MN U SDM309B Rev C C 5 Figure C 3 Adapter Cable AS 0749 V 35 ...
Страница 213: ...External Channel Unit SDM 309B Satellite Modem C C 6 MN U SDM309B Rev Figure C 4 Adapter Cable AS 0750 V 35 ...
Страница 214: ...SDM 309B Satellite Modem External Channel Unit MN U SDM309B Rev C C 7 Figure C 5 Adapter Cable AS 0751 RS449 ...
Страница 215: ...External Channel Unit SDM 309B Satellite Modem C C 8 MN U SDM309B Rev Figure C 6 Adapter Cable AS 0752 15 Pin D ...
Страница 216: ...SDM 309B Satellite Modem External Channel Unit MN U SDM309B Rev C C 9 Figure C 7 Adapter Cable AS 0741 RS449 ...
Страница 217: ...External Channel Unit SDM 309B Satellite Modem C C 10 MN U SDM309B Rev Figure C 8 Adapter Cable AS 0753 15 Pin D ...
Страница 220: ...SDM 309B Satellite Modem External Channel Unit MN U SDM309B Rev C C 13 Figure C 9 RS422 MIL STD 188 114 Interface ...
Страница 221: ...External Channel Unit SDM 309B Satellite Modem C C 14 MN U SDM309B Rev Figure C 10 RS422 MIL STD 188 114 Block Diagram ...
Страница 226: ...SDM 309B Satellite Modem External Channel Unit MN U SDM309B Rev C C 19 Figure C 11 V 35 Interface Card ...
Страница 227: ...External Channel Unit SDM 309B Satellite Modem C C 20 MN U SDM309B Rev Figure C 12 V 35 Interface Block Diagram ...
Страница 235: ...External Channel Unit SDM 309B Satellite Modem C C 28 MN U SDM309B Rev Figure C 13 Menu Tree ...
Страница 236: ...SDM 309B Satellite Modem External Channel Unit MN U SDM309B Rev C C 29 Figure C 14 Menu Tree ...
Страница 237: ...External Channel Unit SDM 309B Satellite Modem C C 30 MN U SDM309B Rev Figure C 15 Menu Tree ...
Страница 238: ...SDM 309B Satellite Modem External Channel Unit MN U SDM309B Rev C C 31 ...