Spread spectrum system analysis, development, and testing, in a multipath UHF radio environment
Direct Sequence Spread Spectrum systems presently find use in navigation and military communication systems. In recent years, however, interest has also been shown in the potential of such systems for Land Mobile Radio applications. In particular the broadband Spread Spectrum signal would be useful in combating the effects of narrowband fading experienced in the UHF radio environment. In addition, vast improvements in the performance of digital integrated circuits is leading to the concept of the all-digital radio receiver. One such device made feasible by progress in miniaturisation is the Digital Matched Filter. This work examines the operation of the Digital Matched Filter. It's applicability to Direct Sequence Spread Spectrum Systems is studied with a view to the possible implementation of such schemes in the Land Mobile Radio environment. Emphasis is placed on achieving maximum utilisation of the Digital Matched Filter resource. Information obtained from Digital Matched Filters in a complex baseband receiver is shown to assist rapid code synchronization, RF carrier recovery, and measurement of the multipath transmission channel profile. A practical transmitter/receiver pair is described, and the results obtained suggest that future designers of Direct Sequence Spread Spectrum receivers may obtain benefits from the Digital Matched Filter approach, particularly in the area of rapid code synchronization.