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Ultrasonic respiration/convulsion monitoring apparatus and method for its use

  • US 4,197,856 A
  • Filed: 04/10/1978
  • Issued: 04/15/1980
  • Est. Priority Date: 04/10/1978
  • Status: Expired due to Term
First Claim
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1. Apparatus for non-contact monitoring of movement of a subject comprising:

  • (a) ultrasound source means for generating and transmitting to the abdominal/chest area of a person to be monitored coherent ultrasound whose frequency is controllable by application to said source of a control signal, the transmitted sound wave being reflected from said person to provide a reflected sound wave;

    (b) receiver means positioned to receive said reflected sound wave;

    (c) phase detector means coupled to said ultrasound source means and to said receiver means and adapted to compare the phase of said reflected sound wave to the phase of said transmitted sound wave and to generate a phase difference signal therefrom;

    (d) change detection means coupled to said phase detector means to modify said phase difference signal to generate therefrom a change signal which is proportional to changes in the length of the air path of said transmitted and reflected sound waves between said transmitter means and said receiver means, said change signal thereby exhibiting variations representing the amplitude of respiratory motion when said source means and said receiver means are aimed at the breathing person;

    (e) frequency adjusting means coupled to said change detection means to receive said change signal and coupled to said generating means to adjust the frequency of said signal voltage in response to said change signal so as to maintain substantially constant the number of wave lengths of ultrasound in said air path despite changes in the length thereof; and

    (f) window/alarm circuit means coupled to said change detector means to receive said change signal for determining whether said variations in said change signal lie within a selected range of values representative of proper respiration for a selected interval of time and for sounding an alarm when said change signal does not lie within said selected range for said selected interval of time.

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