The development of a multi-access traffic simulator for the testing of the SKYNET 4 system

This paper describes the development and engineering of a practical traffic simulator for assessing the behaviour of the SKYNET 4 s.h.f. satellite transponders to various access configurations. The simulator encompasses the full input s.h.f. band of the transponders with a minimum access spacing of 50 kHz. Pseudo-random data streams are used to simulate digital traffic between 50 bit/s and 20 Mbit/s. Up to 32 separately tunable accesses are provided with a further provision for expanding each carrier as a comb of up to four carriers while still maintaining the noise and stability specification of the simulator. The generated access levels are such that they interface with the satellite under pre-launch/laboratory test, either by direct interconnection to its repeater amplifier or via a transmission path and the satellite antenna. The equipment is self-contained in a portable console.