A combined analog/digital hybrid multi/channel airborne satellite communication system

Summary form only given. A technical description of a multichannel airborne analog/digital satellite communication system is presented. The system design required the combining of a 60 W class-A HPA and a 200 W class-C HPA onto an eight-element helical array antenna to provide analog and digital multichannel communication services to aircraft that include telephone, data, and TTY. The analog portion of the system uses FM techniques to provide one channel of high quality voice. The digital portion uses A-QPSK (quadrature phase-shift keying)/A-BPSK (binary phase shift keying) modulation schemes with appropriate forward error correction to provide toll quality multichannel voice capability to the aircraft. World-wide communication coverage is provided by the INMARSAT network of satellites and ground stations.<>