Use of matched filters for serial acquisition in a fast frequency-hopping system

The uses of a transversal filter for serial acquisition in a 16000 hops/s covertly coded fast frequency-hopping radio was previously presented by Zein and Chambers (see IEEE MILCOM 89 Conf., p.49.4.1, 1989). The performance of this system is simulated using a bank of filters matched to the quasi-rectangular shapes of various widths of the received pulses. As a result of the simulation, it is found that the performance of the system when using a matched filter is not quite as good as the performance when using a transversal filter. The matched filter requires a longer time to calculate the four-way decision, since the response to the late pulses cannot be calculated until the last sample is received. It shows less sensitivity to errors in the threshold setting, and it can readily be adapted to act as the demodulator once synchronization has been achieved. The hardware implementation of the filter has been constructed in order to compare the actual performance with results from the simulation. The filter was implemented using the high-speed complex processors in the Plessey PDSP family and the MAC chip TMC2210