Ultrasonic non-contact motion monitoring system

Claim 1

A non-contact ultrasonic motion monitoring system for monitoring physiological functions of a moving subject comprising: (a) a stable oscillator for generating a continuous signal and, (b) a means for selecting the frequency of said signal generated by said stable oscillator and, (c) a transmitting ultrasonic transducer to transmit said signal to illuminate said moving subject with sound wave and, (d) the frequency of said signal of said stable oscillator is set with thereon frequency selection means in order that the wave length of said transmitted sound waves is substantially at least 1/2 times shorter than the expected minimum dimensional extent displaced by said moving subject and, (e) a receiving ultrasonic transducer to receive the reflected sound waves indicative of physiological motion from said moving subject, thereby converting it into motion responsive signals and, (f) a means for splitting said motion responsive signals into a first received signal portion and into a second received signal portion and, (g) a means for multiplying said first received signal portion with said stable oscillator signal, substantially in phase, therein containing difference signals indicative of the phase difference between said transmitted and said reflected sound waves and, (h) a means for filtering said received signals corresponding to motion responsive signals of said moving subject and, (i) a comparator receiving said motion responsive signals whereby each time said motion responsive signals passes a set threshold with a positive slope and subsequently recrosses a slightly different threshold with a negative slope, thereby producing a digital output pulse signal and, (j) a D-flipflop having the data input thereof receiving said digital output pulse signal of said comparator and, (k) a means for multiplying said second signal portion with said stable oscillator signal, substantially in quadrature phase, therein containing difference signals indicative of the phase difference between said transmitted and said reflected sound waves and, (l) a means for filtering said received signals corresponding to a range of expected motion responsive signals of said moving subject and, (m) a comparator receiving said motion responsive signals whereby each time said motion responsive signals passes a set threshold with a positive slope and substantially recrosses a slightly different threshold with a negative slope, thereby producing a digital output pulse and, (n) said D-flipflop having the clock input thereof receiving said digital output pulse of the said comparator.