Aliasing’s Study on Bandpass Sampling

The increase in the complexity of algorithms for digital processing of RF signals is limited by the need to increase the sampling rate. Sub-Nyquist sampling, in particular bandpass sampling, allows us to reduce the sampling rate, determined by the Nyquist-Shannon sampling theorem, and turn to baseband digital processing. In a large number of publications, the issues of choosing the sampling frequency, which makes it possible to eliminate aliasing, are considered. At the same time, there are works devoted to the restoration of signals distorted by aliasing. Therefore, digital signal processing algorithms are of interest, in which the presence of aliasing is allowed. These algorithms make it possible to further reduce the sampling rate and thus make it easier to process wideband signals or narrowband signals over a wider bandwidth. This paper shows that with a fixed sampling rate and a tunable bandwidth of the processed signals, various configurations of the relative position of the alias of the bandpass signal transferred to the first Nyquist zone and its mirror image are possible. The features of aliasing are considered for various configurations of the down-transferred spectrum and for various orders of aliasing.