Processing of Non-Stationary Signal Using Level-Crossing Sampling

The spectral characteristics of multimedia signals typically vary with time. Preferably, the sampling density of them would comply with instantaneous bandwidth of signal. The paper discusses the level-crossing sampling principle, which provides such capability for analog-to-digital conversion. As the captured samples are spaced non-uniformly, the appropriate digital signal processing is required. The non-stationary signal is characterized by time-frequency representation. Its classical approaches are inspected for applicability to analyze the data obtained by level-crossing sampling. Several enhancements of short-time Fourier transform approach are proposed, which are based on the idea to minimize the reconstruction error not only at sampling instants, but also between them with the same accuracy. Additional benefits are gained if the instantaneous spectral range of analysis is complied with local sampling density: artifacts are removed, complexity of calculations is decreased. The performance of algorithms is demonstrated by simulations. Presented research can be attractive for clock-less designs, which receive now an increasing interest. Their promising advantages can play a significant role in future electronics’ development.