Coded excitation using TOP-CS sequences for multi-channel low-power ultrasonics

Abstract

This paper presents a low-power hardware architecture that facilitates the simultaneous transmission and reception of ultrasonic signals when using coded excitations for ultrasonic measurements. With this architecture, long pseudo-periodic coded excitations, which have previously been unsuitable for pulse-echo measurements, can be used to produce high Signal-to-Noise Ratio (SNR) results without an increase in signal dead-zone and without introducing filter artefacts within a set measurement window. We show that a low-power system (±2V peak excitation amplitude without receiver amplification) utilising such coded excitations can achieve the same level of performance as a conventional high-power system (−200V peak excitation amplitude with 15dB receiver amplification) by producing 45dB SNR measurements whilst maintaining a high Pulse Repetition Frequency (PRF) of ≥0.5 kHz. The use of pseudo-periodic sequences to produce quasi-orthogonal sequence families is then demonstrated to allow an arbitrary number of acquisition channels to be used simultaneously with complete crosstalk removal within a set measurement window. Therefore, the work presented here can open the door for the development of simplified low-power multi-channel acquisition systems without sacrificing system performance.