Satellite data transmission and receiving station

Abstract

A satellite signal identification system utilizes distinguishable unique coded identifiers impressed on a carrier sent from a transmitting ground station to be identified. The identifier is recieved and identified by the receiving station to specifically identify a particular underlying carrier signal for reception. The invention utilizes a data modem for transmitting to an earth relay satellite coded identification signals together with various data and error correcting information. An IF carrier signal may be combined with video and/or audio signals, such combined signals being relayed via satellite to the ground station. The MPU of a modem in the ground station finds its counterpart in the MPU of the downconverter that receives via a block downconverter the data, housekeeping and ID signals after the video has been removed. The downconverter first translates the satellite transponder frequency to an IF frequency and sequentially searches for a carrier and the PSK code. The MPU establishes bit sync using the PSK carrier and then searches for the ID signal. The downconverter frequency sweeps to locate a new carrier if the desired ID is not found. Once the desired ID is detected the receiver locks on the signal through the downconverter utilizing the ID signal via a long phase lock loop to cause the local oscillator to track the phase and frequency jitter introduced by an inexpensive downconverter. The MPU demodulates and separates all of the data and housekeeping signals, the latter utilized in an error correction scheme.