High Resolution Noise Radar without Fast ADC

Conventional digital signal processing scheme in noise radars has certain limitations related to combination of high resolution and high dynamic range. The bandwidth of radar signal defines range resolution of any radar: the wider the spectrum the better the resolution. In noise radar with conventional processing the sounding and reference signals are to be digitized at intermediate frequency band and to be processed digitally. The power spectrum bandwidth of noise signal which can be digitized with ADC depends on its sampling rate. In currently available ADCs the faster is sampling rate the smaller is its depth (number of bits). Depth of the ADC determines relation between the smallest and highest observable signals and thus limits its dynamic range. Actually this is the main bottleneck of high resolution Noise Radars: conventional processing does not enable getting high range resolution and high dynamic range at the same time. In the paper we discuss ways to go around this drawback by changing signal processing ideology in noise radar. We present results of our consideration and design of two types of high resolution Noise Radar which uses slow ADCs: noise radar with digital generation of sounding signal and analog evaluation of cross-correlation and stepped frequency noise radar. We describe main ideas of these radar schemes and results of experimental tests of the approaches.