Bpsk Encoding - Comtech EF Data SNM-1001L Installation And Operation Manual

SNM-1001L Satellite Modem
Introduction
•
8-PSK: 8 discrete phase angles represent the 8 possible states of a symbol.
Note: The code rate determines the number of symbols per bit.
1.6.3.1

BPSK Encoding

The modulator converts transmitted baseband data into a modulated BPSK carrier at
2.4 kbps to 1.25 Mbps (1/2 rate). Using vector analysis of the constellation pattern, BPSK
represents one symbol with the carrier phase either at 0° or 180°. The 1/2 rate encoding at
the convolutional encoder provides two symbols output for every bit input.
Uncoded (1/1 rate) BPSK operation also is allowed from 4.8 kbps to 2.5 Mbps.
1.6.3.2 QPSK Encoding
The modulator converts transmitted baseband data into a modulated QPSK carrier at the
following parameters:
•
4.6 kbps to 5.0 Mbps
•
4.8 kbps to 2.5 Mbps
•
7.2 kbps to 3.75 Mbps
•
8.4 kbps to 4.375 Mbps
Using vector analysis of the constellation pattern, QPSK represents a symbol with the
carrier phase angle at 45°, 135°, 225°, or 315°. The 1/1, 1/2, 3/4, and 7/8 rates encoded at
the convolutional encoder provide the desired input/output bit rates.
Code Rate Symbols/Bit
1/2 2
1/1 1
(1/1 rate, uncoded)
(1/2 rate)
(3/4 rate)
(7/8 rate)
Code Rate Symbols/Bit
1/1 1
1/2 2
3/4 1.33
7/8 1.143
1–7
MN/SNM1001L.IOM
Bits/Hz
0.5
1
Bits/Hz
2
1
1.5
1.75
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