Time frequency based detection scheme for missile approach warning system (MAWS)

Typically MAWS radars use high pulse recurrence frequencies (PRFs) to ensure unambiguous Doppler measurements of high speed targets. This combination of high PRFs and relatively large range gates means that the most significant constraint against increasing the coherent processing interval is the Doppler smearing phenomena. This paper describes two methods to address this problem. The first method achieves this by explicitly removing the higher order frequency modulation whereas the latter uses a time-frequency distribution to solve the problem. Both the methods show marked improvement in detection performance over standard Doppler processing, with the latter scheme being an implementation of a maximum likelihood solution, approximating optimum performance, though at the cost of added computational complexity. The paper describes the development of the two algorithms and presents an analytic treatment of both. This is followed by a performance analysis of the algorithm based on actual data from an experimental MAWS radar.