Comtech EF Data C5 - Manual (Page 219)

C5/K1/K3 Integrated Satellite Terminal System Theory of Operation
Rev. 0 5-9
5.3.3.1 BPSK Encoding
The modulator converts transmitted baseband data into a modulated BPSK carrier at
2.4 to 1250.0 kbit/s (1/2 rate). Using vector analysis of the constellation pattern, BPSK
represents one symbol with the carrier phase at either 0
# or 180#. The 1/2 rate encoding
at the convolutional encoder provides two symbols output for every bit input.
Code Rate Symbols/Bit Bits/Hz
1/2 2 0.5
5.3.3.2 QPSK Encoding
The modulator converts transmitted baseband data into a modulated QPSK carrier at 4.8
to 4375.0 kbit/s.
Using vector analysis of the constellation pattern, QPSK represents a symbol with the
carrier phase angle at 45
#, 135#, 225#, or 315#. The 1/2, 3/4, and 7/8 rates encoded at the
convolutional encoder provide the desired input/output bit rates.
Code Rate Symbols/Bit Bits/Hz
1/2 2 1
3/4 1.5 1.33
7/8 1.143 1.75