A near-optimum detector with reduced out-of band response for narrowband signals

Reduced spectral response in adjacent spectral bins is very desirable for detectors since it gives capability to detect narrow band signals in the presence of unknown interference and colored noise. Conventionally, this is achieved by applying a smoothing window on the signal at the cost of detection performance. In this correspondence, a new method of detecting narrowband signals that uses a close approximation to the matched filter and the extrapolated input signal is proposed. The filter used has a frequency response that is very closely equal to that of the matched filter within a doppler bin and nearly zero response outside it.