The Case of FM-AM vs FM-FM Telemetry

The future role of frequency-division multiplex telemetry is discussed and related to the sampled data problem of time-division multiplex telemetry. It is concluded that the frequency-division method will continue to have important applications and the question is raised regarding what is a desirable frequency-division system on which to standardize in the future. An examination of the shortcomings of the FM-FM system and the electronics state of the art leads to the proposal of an FM-AM system to replace the FM-FM system. The AM radio link would be of synchronous type, without threshold, so that the FM-AM system is properly viewed as an FM system with frequency conversion. This has important advantages in spectrum utilization, receiving station design, and data reduction.