Implementation of an EHF Frequency-Hopping Simulator

摘要

EHF SATCOM offers communications robustness by incorporating wide band frequencyhopping and onboard satellite processing to mitigate the effects of electronic interference. The same characteristics that make EHF SATCOM robust however, also make it complex. Satellite onboard processing means that synchronization must be achieved for both the uplink and the downlink. The Skynet EHF (extremely high frequency) Downlink Trials consisted of several week long accesses over Skynet 4A during 1993 and 1994. The whole link (up to satellite and back down) was used to simulate an EHF frequency hopped downlink from a processing satellite. To aid in the analysis of EHF SATCOM, inhouse ground terminal and payload simulators were developed. For this set of trials, the synchronization and communications aspects of an EHF frequency hopped downlink using burst differential phase shift keying modulation were investigated. The payload and ground terminal simulators were developed using a combination of off the shelf components and inhouse developed hardware and software. The implementation of these two simulators is detailed in this report after the description of the experimental waveform. The Skynet EHF Downlink Trials were successfully run in week-long experiments over two years. Frequency hopped spatial and time synchronization were achieved. Data and voice communications were demonstrated with and without time diversity. Problems with the commercial frequency hopping synthesizers precluded the completion of some of the data communications experiments in the time available.