Wideband Undersampling Digital Receiver

Abstract

An antenna receives an analog waveform and an analog signal indicative of the amplitude and frequency of the analog waveform. The analog signal is processed in a plurality of parallel digital processing channels each arranged to digitize the analog signal at a corresponding sampling frequency fsi to produce a plurality of digital signals. A discrete Fourier transform is applied to each of the digital signals output to produce a corresponding plurality of unique Fourier spectra of length mi=(fs;)(TL;) where TLi is the integration time for the discrete Fourier transform for each digital processing channel. The lengths of the Fourier spectra (m;) are selected to be pairwise relatively prime. The discrete Fourier transform encodes the signals in same form as the symmetrical number system (SNS). A SNS-todecimal algorithm is then applied to the detected bin values (a;) to determine the numerical value of the frequency f of the analog waveform. The receiver resolves all undersampiing ambiguities exactly, thereby relaxing the speed requirements on the digital section of the receiver.