Analysis of Ultra Wide Band Noise Radar with Randomized Stepped Frequency

Step frequency radar has been used for a long time in wide-band radar applications, such as turntable ISAR, airborne VHF SAR and ground penetration radar. The frequency is stepped linearly with constant frequency change, and range cells are formed after FFT-processing of the received frequency samples. The total covered bandwidth defines the range resolution, and the length of the frequency step restricts the non-ambiguous range interval. Random choice of the transmitted frequencies suppresses the range ambiguity and improves the ECCM performance. In this paper, the ambiguity function and the noise floor limiting the possible side lobe suppression are analyzed. Experimental results are compared with theoretical predictions using sets of randomly distributed radar raw data obtained from linear step frequency radar measurements.