Unambiguous Doppler frequency estimation in an MTI radar

• Published in: IEE conference publication pp. 530 - 534
• Main Author: Misiurewicz, J
• Format: Conference Proceeding
• Language: English
• Published: London IEE 1997
• Subjects: Applied sciences; Detection, estimation, filtering, equalization, prediction; Exact sciences and technology; Information, signal and communications theory; Other topics in statistics; Radar equipment, systems and applications; Radar theory; Radiolocalization and radionavigation; Signal and communications theory; Signal processing and detection; Signal, noise; Telecommunications; Telecommunications and information theory; radar tracking; Doppler return signal; object velocity; minimum sampling interval; Chinese remainder theorem; MTI radar; integer remainders; periodically nonuniform sampling; sampling intervals; long range radar; frequency estimation; radar signal processing; blind speed effect; unambiguous Doppler frequency estimation; estimation methods; microwave pulse; pulse radar; target tracking; signal sampling; moving target indicator radar; Doppler radar; signal frequency; Doppler frequency; Parameter estimation; Algorithm; Signal estimation; Radar
• ISBN: 9780852966983; 0852966989
• ISSN: 0537-9989
• DOI: 10.1049/cp:19971732

In pulse radars, the Doppler frequency estimation is used to determine the object velocity. Many estimation methods have been developed for signals sampled with a rate higher than required by the Shannon sampling theorem. However, in a long range radar the minimum sampling interval is determined by the time needed for the microwave pulse to travel to and from the range perimeter. The frequencies of the Doppler return signal may significantly exceed the resulting unambiguous frequency range. Thus, an MTI (moving target indicator) radar lacks the ability to measure velocity unambiguously. In MTI radar systems periodically nonuniform (staggered) sampling is used to avoid the blind speed effect. M different sampling intervals are used in one stagger cycle. We show that in this case, signal frequency can be recovered from the samples. The method proposed exploits the properties of integer remainders derived from the Chinese remainder theorem. With a proper choice of sampling intervals, it allows for ambiguity resolving in a wide frequency range and with low error sensitivity.