RECEIVER DEVICE IN A SATELLITE COMMUNICATION SYSTEM

摘要

A receiver device for a satellite communication system capable of transmitting in either of two modes detects which transmission mode is currently in effect and adjusts its signal processing and output stages accordingly. The transmission may be recognized by reference to either the encoded information or the electromagnetic medium itself of the received electromagnetic transmissions. In one mode, only audio signals and related information are broadcast in FM form whereas in the other mode, a video image signal is also included, while a subcarrier signal is modulated by an audio and/or a data signal. The receiver system checks either the sub-carrier signal or video synchronization signals in the incoming transmissions to determine the transmission mode. The receiver may also be forced to a predetermined mode upon power-up to prevent spurious mode-selection errors.