Patent ID: 8909312
Filing Date: 2014-12-09
Classification: A61B

Abstract:
1. A signal acquisition circuit for detecting a wanted signal in a composite signal containing the wanted signal and an unwanted signal, where the highest frequency in the unwanted signal is higher than the highest frequency in the wanted signal, comprising: a first sensor arranged to sense the composite signal, the composite signal being sensed at a rate that is at least equal to the Nyquist rate for the highest frequency in the wanted signal and less than the Nyquist rate for the highest frequency in the unwanted signal; a second sensor arranged to sense the unwanted signal, without the wanted signal, at a rate that is at least equal to the Nyquist rate for the highest frequency in the unwanted signal; an analog-to-digital converter arranged to receive the outputs of the first sensor and the second sensor, and sample the received outputs of the first sensor and the second sensor at a sampling rate that is at least equal to the Nyquist rate for the highest frequency in the unwanted signal; a demultiplexer arranged to receive the output of the analog to digital converter and output a signal representative of the unwanted signal separately from a signal representative of the composite signal; and a filter arranged to subtract the output signal representative of the unwanted signal from the signal representative of the composite signal and thereby output a signal representative of the wanted signal. containing the sum of the wanted signal and the unwanted signal sampled at a low rate at least equal to the Nyquist rate for the wanted signal but less than the high rate and a second component containing the unwanted signal sampled at the high rate.