Radio Relay System Performance in an Interference Environment

Analysis of the relationship of telephone and TV message quality as received over a radio relay system to the relative level of rf interference and noise at the inputs to the repeaters and terminal receiver, for various message types (analog, digital, combinations) and modulation/demodulation methods. The output message quality is expressed in terms of the wanted-to-unwanted signal ratios (WUSRs) at the rf inputs. New analytic methods include separating the effect of the demodulators from that of the terminal signal processing and demultiplexing equipment, making it possible to write a general functional equation applicable to all radio systems employing a given type of repeater. The comparison of many modulation and signal processing combinations for arbitrary interference is simplified by using white thermal noise as a reference case. Message quality objectives are developed, and from them the necessary WUSRs, for both terrestrial and satellite communication systems. Appendixes give data on the characteristics of messages, modulated carriers, and noise weighting and preemphasis networks.