Doppler signal detection using stepped frequency noise radar

Abstract

Current paper deals with radar design obtained by combination of two approaches: stepped frequency radar and noise radar for the purposes of SAR imaging. The idea of operation of such combination is following: instead of single frequency signal a narrowband noise signal is radiated in a stepped frequency radar. The processing is done in the same way as in usual stepped frequency radar. Noise modulation will lead to limitation of area within which the radar is sensitive by the correlation length of the noise signal. Analog filter in the receiver will filter out fluctuations caused by the targets outside the noise signal correlation interval. This gives possibility to make a radar using stepped frequency concept but with limited sensitivity zone. This can be helpful for omitting such drawbacks of stepped frequency approach as presence of range ambiguities, low electromagnetic compatibility, high probability of interception and low interference immunity. Besides, it preserves such desired quality of stepped frequency radar as ability to generate high resolution range profiles using a narrowband receiver. This solves problem of lack of ADCs with both high depth and sampling rate which leads to difficulties in design of high performance noise radars using conventional approach. The aim of the paper is to describe the approach, to present results of experiments aimed on detection of Doppler signal using the approach and limitation of observed ranges via variation of noise modulation bandwidth.