Comtech EF Data SDM-309B - Manual (Page 20)

SDM-309B Satellite Modem Introduction
MN/U-SDM309B Rev. # 1-1–7
The modem consists of the following assemblies:
Assembly Drawing No.
Chassis with Power Supply AS/1100-3
PCB, Monitor and Control AS/0356
PCB, Modulator AS/0773-X
PCB, Demodulator AS/0778-X
PCB, Viterbi Decoder AS/2133*
PCB, Front Panel Control Board AS/0361
PCB, Mother Board AS/0979-1
PCB, Internal Channel Unit
(IBS)
(D&I)
AS/1010 &
AS/1011 or
AS/1455
(External Channel Unit) See Appendix C
PCB, Mod Daughter Variable Rate AS/0930-2 or
PCB, Mod Daughter Fixed Rate AS/0715
PCB, Demod Daughter Variable Rate AS/0929-2 or
PCB, Demod Daughter Fixed Rate AS/0698
Note: X= various options available on the modulator and demodulator boards. Refer to
Table 6-3 for more information on the options available for each board.
*Older versions of the Viterbi Decoder board can also be used in the SDM-309B
modem. Refer to Chapter 5, Section 5.2 for more information on the available revisions
and compatibility information.
1.4 System Specification
Table 1-1 lists the operating specifications of the modem. The bit energy-to-noise ratio
(Eb/N0) required to achieve 10-5 and 10-7 bit error rates is listed in Table 1-2. The
typical bit error rate performance of the modem is shown in Figure 1-5, and a typical
output spectrum of the modem is shown in Figure 1-6.
Table 1-1 SDM-309B Satellite Modem Specification
System Specifications
Operating Frequency Range 50 to 90 MHz, or 100 to 180 Mhz
Synthesized in 2.5 KHz Steps
Type of Modulation Quadrature Phase Shift Keying
Operating Channel Spacing Less Than .5 dB degradation operating with
2 adjacent like channels each 10 dB higher
at 1.3 times the symbol rate or 75 KHz
minimum
Bit Error Rate See Table 1-2
Digital Interface
IBS/M1200P
D&I/M1200P
External Channel Unit
(See Appendix C) V.35, RS/422, & G.703
G.703 - T1 & E1
RS422/449, DS1, V.35, G.703
Digital Data Rate 64 to 2048 Kb/s Configurable Choice
of up to Four pre-defined fixed Rates
or Variable Rate Option