Analysis of non-idealities of low-pass filter in random demodulator

Abstract

Random Demodulator (RD) is a novel signal acquisition scheme based on compressed sensing (CS). It is able to acquire signals continuous in time and sparse in frequency at a sampling rate far below the Nyquist frequency. In the RD architecture, low-pass filter plays a role of anti-aliasing and is also the main part of the measurement matrix which should be characterized accurately. In this paper, we analyze the impact of the low-pass filter’s non-idealities. If the filter parameters deviate from their ideal values, there will be mismatch between the ideal impulse response used in the measurement matrix and the practical, which will degrade the reconstruction performance. The results show that with the increase of the degree of mismatch, the quality of signal reconstruction, measured by signal to noise ratio (SNR), declines. The results suggest accurate calibration is needed in practical use.