Amplitude-companded single-sideband modulation

ACSSB (amplitude-companded single sideband) is a narrowband modulation method using a single sideband with a pilot tone, allowing an expander in the receiver to restore the amplitude that was severely compressed by the transmitter. This mode promised greater robustness and fade resistance on HF than even SSB, but was pretty much leapfrogged in favor of spread spectrum, which solves the problem even better.

Most of the noise reduction circuits used in audio recording are also variations of companding.

ACSSB is being used by air-to-ground phones, as well as mobile satellites.

External references

• Mobile and Mobile-Satellite Services
• Property Rights In Radio Communication: The Key to the Reform of Telecommunications Regulation Milton Mueller The Cato Institute June 3, 1982