DMD50 Universal Satellite Modem
Theory of Operation
TM118 – Rev. 1.1
3-17
Table 3-1. Reed-Solomon Codes
Type of
Service
Data Rate
(Kbps)
R-S Code
(n, k, t)
1
Bandwidth
Expansion
[ (n/k) -1 ]
Interleaving
Depth
Maximum
2
R-S Codec
Delay (ms)
Small IDR
(With 16/15
O/H)
64
128
256
384
512
768
1024
1536
(126, 112, 7)
(126, 112, 7)
(126, 112, 7)
(126, 112, 7)
(126, 112, 7)
(126, 112, 7)
(126, 112, 7)
(126, 112, 7)
0.125
0.125
0.125
0.125
0.125
0.125
0.125
0.125
4
4
4
4
4
4
4
4
115
58
29
19
15
10
8
5
IDR
(With 96
Kbps O/H)
1544
2048
6312
8448
(225, 205,10)
(219, 201, 9)
(194, 178, 8)
(194, 178, 8)
0.0976
0.0896
0.0899
0.0899
4
4
4
4
9
7
2
<2
8PSK
1544
2048
6312
8448
(219, 201, 9)
(219, 201, 9)
(219, 201, 9)
(219, 201, 9)
0.0896
0.0896
0.0896
0.0896
8
8
8
8
18
13
4
3
DVB
All
(204, 188, 8)
0.0851
12
-
1. n = code length, k = information symbols and t = symbol error correcting capability.
2. Design objective.
3.9 Asynchronous Overhead Operation (Framing/Multiplexer Capability)
The Asynchronous Framing/Multiplexer is capable of multiplexing a relatively low-speed overhead
channel onto the terrestrial data stream resulting in a slightly higher combined or aggregate data
rate through the modem. The overhead channel is recovered at the far end. This added channel
is termed variously “An Overhead Channel”, ”Service Channel”, “Async Channel” or in IESS
terminology an “ES to ES Data Channel.” The basic frame structure used by the multiplexer is
that specified in the IESS-309 Standard, resulting in a 16/15 Aggregate ratio of overhead & data
to data rates.
For Regular Async:
(Standard IBS), the Baud Rate is approximately 1/2000
of the Data Rate listed in Table 3-3.
For Enhanced Async:
(IBS Async.), the Baud Rate is selectable, but Data Rate
is limited.
The maximum Baud Rate is 19,200 bps for IBS Async. Two software-controlled modes are
designed into the card to best utilize the available bits; “Standard IBS” and “IBS (Async)”. The
characteristics of the Channel Interface is also determined by the standard or Async mode.
The Async Channel can be set under software-control to either RS-232 or RS-485 mode. The pin
assignments for both modes are shown in Table 5-3.
Summary of Contents for DMD50
Page 2: ......
Page 3: ......
Page 16: ...DMD50 Universal Satellite Modem Table of Contents TM118 Rev 1 1 xv...
Page 17: ......
Page 20: ...DMD50 Universal Satellite Modem Introduction TM118 Rev 1 1 1 3...
Page 21: ......
Page 27: ...Installation DMD50 Universal Satellite Modem 2 6 TM118 Rev 1 1...
Page 53: ...Theory of Operation DMD50 Universal Satellite Modem 3 26 TM118 Rev 1 1...
Page 97: ...User Interfaces DMD50 Universal Satellite Modem 4 44 TM118 Rev 1 1...
Page 122: ...DMD50 Universal Satellite Modem Rear Panel Interfaces TM118 Rev 1 1 5 25...
Page 123: ......
Page 132: ...DMD50 Universal Satellite Modem Maintenance and Troubleshooting TM118 Rev 1 1 6 9...
Page 133: ......
Page 158: ...DMD50 Universal Satellite Modem Technical Specifications TM118 Rev 1 1 7 25...
Page 159: ......
Page 162: ...DMD50 Universal Satellite Modem Appendix A TM118 Rev 1 1 A 3...
Page 163: ......
Page 170: ...DMD50 Universal Satellite Modem Appendix B TM118 Rev 1 1 B 7...
Page 171: ......
Page 174: ...DMD50 Universal Satellite Modem Appendix C TM118 Rev 1 1 C 3...
Page 175: ......
Page 184: ...DMD50 Universal Satellite Modem Appendix D TM118 Rev 1 1 D 9...
Page 185: ......
Page 192: ...DMD50 Universal Satellite Modem Appendix E TM118 Rev 1 1 E 7...
Page 193: ......
Page 200: ...DMD50 Universal Satellite Modem Appendix F TM118 Rev 1 1 F 7...
Page 201: ......
Page 205: ...Appendix G DMD50 Universal Satellite Modem G 4 TM118 Rev 1 1...
Page 224: ...DMD50 Universal Satellite Modem Appendix H TM118 Rev 1 1 H 19...
Page 225: ......
Page 231: ...Appendix I DMD50 Universal Satellite Modem I 6 TM118 Rev 1 1...