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US 4,122,427 AGranted
Motion monitor
OwnerHerbert Karshinventor
Life of this patent
Estimating the term…
Abstract
A motion monitor particularly useful for monitoring infant respiration, and comprising an oscillator driving an ultra-sonic wave generator, a receiver for ultra-sonic echoes, a phase detector for detecting phase shift between the outputs of th detector and oscillator and means for recovering the respiration envelope from the output of the phase detector. In a preferred embodiment the system includes a phaselocked loop using selected very low frequencies in the output of the phase detector to control the oscillator frequency.
Claims15
Apparatus for monitoring substantially cyclic movement of a subject, and comprising, in combination:
- generating means including a voltage controlled oscillator, for generating a substantially continuous ultrasonic wave and for directing said wave in a beam toward said subject;
- detecting means for detecting the reflection of said ultrasonic wave from said subject;
- and
- means for measuring the path length of said ultrasonic wave from said generating means to said subject and thence to said detection means as a function of the phase difference between the ultrasonic wave generated by said generating means and the ultrasonic wave detected by said detecting means so that substantially cyclic movement of said subject provides phase modulation of the detected ultrasonic wave upon corresponding changes in said path length.
1 more element
Dependencies are inferred from the claim text.