Sub-Nyquist Time-Based Sampling Of Fri Signals

In this demo, we present dedicated hardware for sub-Nyquist sampling and reconstruction for finite rate of innovation (FRI) signals using an integrated and fire time encoding machine (IF-TEM). The classic approach for the sampling and recovery of a signal is based on acquiring the signal values in discrete equally spaced intervals over time, at a rate greater than or equal to the Nyquist rate of the signal. Time encoding, which is a special case of a time-based sampling mechanism, is an alternative approach to conventional sampling. An analog signal is represented by a sequence of time instants [1]. In IF-TEM sampling, the analog input signal is first integrated, and then the integrated signal is compared to a threshold. Each time the threshold is reached, time points or firing instants are recorded and which encode the information of the analog signal. We proposed a robust IF-TEM-based sampling framework for FRI signals and demonstrate the same through a hardware prototype. Our demonstration platform consists of the following components: (1) a vector signal generator with delay capabilities that generate the FRI signals, (2) an IF-TEM sampler that consists of an integrator followed by a comparator, and (3) a counter that encodes the time. The time instants are then used by a reconstruction algorithm to estimate the FRI signal parameters. The hardware prototype that measures the time instants will be presented along with a dedicated GUI depicting the computed performance measures and comparing it to sub-Nyquist using IF-TEM operation. References: 1. A. A. Lazar and L. T. Toth, "Perfect recovery and sensitivity analysis of time encoded bandlimited signals," IEEE Transactions on Circuits and Systems I: vol. 51, no. 10, pp. 2060-2073, Oct. 2004.