DATA PACKET SATELLITE COMMUNICATION SYSTEM

摘要

A satellite communication system comprises a central broadcast station (10) in satellite communication with a plurality of user terminals (12) each of which can make requests for broadcast data from the central broadcast station. Each user terminal includes means (Fig. 2) for sending each user request as one or more data packets (50) each of which is transmitted as a modulated carrier whose frequency is randomly selected from a set of N predetermined frequencies common to all the user terminals. Each data packet includes data identifying the particular user terminal from which it originates, and the central broadcast station includes N channels (52/54) each arranged to receive and demodulate data packets transmitted at a respective one of the N carrier frequencies.