Serial acquisition in a 16 khop/s fast-frequency-hop system

摘要

A system for acquiring synchronisation in a 16000 hops/s covertly coded frequency hop radio, which uses a serial search technique, is presented. The frequency-hop system uses 7000 channels spaced at Delta f=25 kHz. The information rate is sent at 1 bit/hop and is conveyed by FSK modulation. A convenient method for estimating the acquisition time and the probability of missing the genuine signal is derived and used to investigate the effect of interference and fading. Two classes of baseband filtering were used: a lowpass transversal filter and a bank of matched filters. Two sorts of fading of the genuine signal were considered. One model assigns a constant magnitude to the genuine signal for typically 90% of the time and is totally faded for the rest. The other is a two-path fading model. The jamming signal is modelled as pulses at random times and frequencies.