A Low-Power Integrated Circuit for Interaural Time Delay Estimation Without Delay Lines

Abstract

A low-power IC for the estimation of the delay between two infinitely clipped (digital) signals is designed and implemented in a 0.35-μm standard CMOS technology. The proposed circuit is based on a sliding-mode control system and does not need past values of the inputs, which are usually stored using chains of digital registers or analog delay lines and significantly increase the power consumption. The IC is intended to work in ultralow-power miniature sensor network nodes performing localization in the audio range [20, 1000] Hz, as part of a forest environmental protection network. Power dissipation results show a core power consumption of 1.04 μW at 3.3 V and only 282 nW at 1.8 V-in both cases with a clock frequency of 200 kHz. The circuit is fully operative and was successfully tested on field as part of a low-power bearing sensor unit.Index Terms-Acoustic signal processing, bearing angle estimation, CMOS digital integrated circuits, correlation-derivative circuit, delay estimation correlation methods, direction of arrival estimation, low-power consumption, low-power sensor networks, microphone arrays.

Fast and low power integrated circuit for impulsive sound localisation using Kalman filter approach

“…Thus, this IC should be adequate to capture the bearing angle of a gunshot sound. Besides, the energy required by the IC to perform the calculation is equal to or even lower than the best result reported so far in the literature [8], owing in great part to its fastest convergence time. …”

“…Considering a 200 Hz signal, the energy required for an estimation is E ¼ 0.5 × 6 × 9.8 mW/200 Hz ¼ 147 nJ. For the sake of comparison, the IC in [8] requires 156nJ per estimation (comparisons based on a 150 ms convergence time for a 300 ms delay estimation, as defined in [8], with a power consumption of 1.04 mW). This system assumes periodic, stationary signals 3 Convergence time is the longest one required by LMS-adaptation rule used by IC [5] Conclusions: The presented IC is able to estimate the ITD of a couple of signals captured with two microphones within six edges of the incoming signal (15 ms for a 200 Hz input signal, 3.5 ms for a 1 kHz input signal), with a precision of 5 us.…”

“…Therefore, the estimation needs to be fast. The methods reported in the literature cannot be applied to this case because they either assume a periodic and stationary signal [3,4], or they are too slow [5][6][7][8][9]. …”

“…A further simplification may be obtained by evaluating W(k) off-line. In this proposal, the model and estimator variance are estimated off-line from real measurements[8], considering a model standard deviation of s v ¼ 2.5 ms (corresponding to half LSB of the…”

Sound Source Localization through 8 MEMS Microphones Array Using a Sand-Scorpion-Inspired Spiking Neural Network

“…The performance of the system, with low power CMOS VLSI design, is of the order of 1° error margin and similar standard deviation for the bearing angle estimation (Cauwenberghs et al, 2005; Julian et al, 2006; Pirchio et al, 2006). A very low power implementation for interaural time delay (ITD) estimation without delay lines with the same ASU unit is reported by Chacon-Rodriguez et al with an estimation error in the low single-digit range (Chacon-Rodriguez et al, 2009). …”