Experimental investigations of digital signal processing techniques in an FMCW radar for naval application

Recently we observe increased interest devoted to frequency modulated continuous wave (FMCW) radars, mainly because of their low probability of intercept (LPI) properties. In such radars the information on range of targets appears in frequency domain and it is obtained on the base of spectrum analysis carried out for a so called beat signal. The beat signal is a product of mixing the received signal with the transmitted signal in the receiver of homodyne configuration. In the paper there are briefly described principle of operation and design of the FMCW radar, at the beginning. Next, special attention is paid to digital processing of the beat signal. A prototype of an FMCW radar for naval application was made in Telecommunications Research Institute. The prototype was tested among other for optimisation of digital signal processing in real sea environment. The noncoherent processing comprises FFT, CFAR thresholding, binary integration and scan-to-scan correlation. The paper deals with an experimental study how different algorithms influence signal detection. The method of approach consists in estimating the detection performance under various conditions. We examine the detection performance in relation to e.g. kind of smoothing window in FFT, length of FFT, length of CFAR window, rule of integration. Obtained results are presented.