Modulation Improvements:
Constellation
Comtech Proprietary & Confidential 8
Efficiency Legacy Method Newer Method Reason
2 Bits / Hz &
3 Bits / Hz
QPSK / 8PSK QPSK / 8PSK Highly Efficient –
no changes, no
amplitude element
4 Bits / Hz 16QAM 16APSK Improved
performance
when amplifiers
run into saturation
5 Bits / Hz Relatively Unused 32APSK Enables extreme
BW vs. throughput
Minimizes effects
of compression
