Abstract
A new approach to scanning system for sensor array is proposed. In the multiplex stage of the proposed system, output signals of sensors are modulated by orthogonal sequences, summed to a serial signal, and quantized. The modulating sequences are so selected that the signal power from the sensor is timespread. In the demultiplexing stage, the quantized sequence are multiplied by demodulating sequences and integrated with respect to time.
In this paper, the principle of scanning is described, and the method using Maximal-length binary-sequences (M-sequence) is proposed. Noise effect is evaluated for given length of M-sequence and number of sensors. From the evaluation, we conclude that the proposed system improves the signal to noise ratio compared with conventional time-division-multiplex.
We discuss the application of the method to ultrasound sensor array. Experimental system is constructed using 16 channel ultrasound microphone array and analogue switches. Experimental results demonstrates the ability of the method to data scanning for coherent sound source localization. And computer simulation which assumes the same experimental set up indicates the additive-noise reduction property of the method.
