Joint frequency and angle of arrival estimation using the Chinese Remainder Theorem

One of the main tasks in Electronic Support (ES) is the determination of the carrier frequency and the direction of arrival (DOA) of threat signals. In modern days, these two tasks are addressed using two different techniques, namely Instantaneous Frequency Measurement (IFM) [1-4] and Interferometric Direction Finders (IDF) [5,6]. Furthermore, ES systems must scan an ultra-wide frequency band, thus making the digitization and signal processing very challenging. This paper describes a joint IFM-IDF that uses three different sampling rates for each of the three channels needed to estimate DOA. The sampling rates are kept extremely low as compared to the bandwidth to be scanned. The joint estimation of the DOA and carrier frequency is possible by exploiting the principles of the Chinese Remainder Theorem.