Doppler radar for detecting targets in ground clutter - uses spectral analyser to process fast fourier transform algorithm using synchroniser to distinguish range gates

摘要

A synchroniser (101) drives a frequency synthesiser (102) to produce a frequency agile output for a transmitter (103) and receiver (106). The transmitter produces pulses at a predetermined repetition rate for transmission via a circulator (104) and antemma (105). The receive pulses are applied to a coherent phase receiver which uses the synthesiser output for the demodulation. The demodulated output comprises a series of video frequency pulses following at random. These are applied to an acquisition system and memory (107). This operaties sequentially to provide signals corresponding to the different range gates. A spectral analyser (108) processing an FFT algorithm uses the synchroniser to distinguish between the range gates. A discriminator (109) indicates pressrue or absence of a target for each range gate and a second discriminateo (110) improves probability of a target rather than a false alarm.