AN ADVANCED MULTILEVEL FREQUENCY HOPPING TRANSMISSION TECHNIQUE,

摘要

Multilevel matched filter transmission system which uses discrete frequency hopping techniques is described. The system is intended for narrow band digital circuits in a multipath and jamming environment. It has application to narrow band troposcatter links and reflective scattering from highly nonstationary media such as orbital chaff and ion clouds. The system can also be used to advantage for omnidirectional communication via a network of low altitude satellites because of its capability of discriminating between multiple satellite returns and using them constructively. The predicted performance of the system is discussed in detail. In brief,the system provides increased information efficiency,increased resistance to jamming and a fair degree of inherent security. It is about 30DB better in signal-to-jam discrimination than a plausible FM transmission system and equals or slightly exceeds in all respects the performance of the Massachusetts Institute of Technology rake modulation system. (Author)