Frequency selective fading using the Hewlett Packard 11759C RF simulator

Frequency selective fading results from a wide range of different causes, these include nuclear scintillation (as produced by a high altitude nuclear explosion, HANE) which usually affects satellite communications links to some degree and multipath in built up areas which usually affects personal communications systems. To be able to deterministically produce the required frequency selective fading (FSF) parameters, such as coherence bandwidth, decorrelation time and fade rate, means that performance characteristics of communicating devices, destined for scenarios where FSF is likely to occur, can be evaluated in a laboratory. In recent years the way of simulating FSF was by using a number of tapped delay lines to provide the multipath required but, although effective, is prohibitively expensive for some organisations. DRA Defford have generated appropriate control files for the Hewlett Packard 11759C RF simulator to enable the economic testing of MILSATCOM modems against the effects of FSF. The system deterministically controls the coherence bandwidth, decorrelation time and fade rate.