Patent ID: 8979771
Filing Date: 2015-03-17
Classification: A61B

Abstract:
1. A system to generate an electrical signal indicative of muscle activity, comprising: a transducer operative to convert acoustic impulses emitted from a muscle into a corresponding electrical signal; and signal processing circuitry operative to (a) delay a first portion of the signal in time domain, which is present at a first moment in time, by a known delay amount to produce a time-shifted instance of the signal in the time domain; (b) correlate a second portion of the signal in the time domain, which is present at a second moment in time that follows the first moment in time, with the time-shifted instance of the signal in the time domain to produce a correlation and (c) generate an output signal in the time domain, which is representative of a contractile force of the muscle based upon density of impulses extracted by the correlation; wherein the signal processing circuitry includes a first correlator to produce the correlation; a second correlator in parallel with the first correlator to correlate the second portion of the signal with an impulse feature in the time domain; and a differential amplifier, having inputs driven by the first and second correlators, to remove low frequency noise.