Comtech EF Data SNM-1001L - Manual (Page 264)

SNM-1001L Satellite Modem Revision 1
Specifications MN/SNM1001L.IOM
A–26
A.10.12 Receive Doppler/Plesiochronous Buffer Size
The receive Doppler buffer size can be set by the operator from:
1. Bypass.
2. 32 to 262144 bits, in 16 bit steps for all data rates.
3. Selectable in ms, from 1 to 99 in 1 ms steps, for data rates < 2.6 Mbps.
4. Selectable Frame Format G.704 or None.
A.10.13 Switch Faults
• Modulator Fault Open collector output, 15V maximum, 20 mA maximum
current sink, fault is open circuit
• Demodulator Fault Open collector output, 15V maximum, 20 mA maximum
current sink, fault is open circuit
A.11 Decoding
A.11.1 BPSK Decoding
Using vector analysis of the constellation pattern, BPSK represents one symbol with the
carrier phase either at 0
° or 180°. The characteristics for BPSK are provided in the
following table.
Code Rate Symbols/Bit Bits/Hz
1/1 1 2
1/2 2 0.5
5/16 3.2 0.3125
21/44 2.1 0.477
A.11.2 QPSK Decoding
The demodulator converts transmitted baseband data into a modulated QPSK carrier at the
following parameters:
4.8 kbps to 2.5 Mbps (1/2 rate)
7.2 kbps to 3.75 Mbps (3/4 rate)
8.4 kbps to 4.375 Mbps (7/8 rate)