Dual frequency heart rate monitor utilizing doppler radar
First Claim
1. A heart rate monitor comprising in combination:
- first means for producing a first radio frequency (RF) signal at a relatively low frequency and for producing a second RF signal at a relatively high frequency;
second means coupled to said first means and adapted for radiating signals therefrom toward a patient whose heart rate is to be measured and for receiving doppler shifted signals back from said patient at the frequencies of said first and second RF signals;
third means for removing the respective RF frequencies from the returned signals leaving the doppler signal components thereof, said doppler signal associated with both RF signals containing signal components of the same values corresponding to patient movement due to respiration, the doppler signal associated with the low RF frequency containing characteristics associated with patient movement due to heartbeat; and
fourth means for combining the two doppler signals to remove the components thereof which are common to both signals and thereby leaving the component of signal which is associated with heartbeat, the number of heartbeats per unit time corresponding to heart rate.
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Accused Products
Abstract
A heart rate monitor for use where direct contact with a patient cannot be made utilizes two continuous radio frequency (RF) signals, one of relatively low frequency and one of relatively high frequency directed toward the patient whose heart is to be determined. Doppler shifted signals are reradiated by the patient back to the monitor. The reradiated low RF signal has doppler components due to bodily motion caused by respiration and heartbeat. The reradiated high RF signal has doppler components due to patient bodily movement caused by respiration. Doppler components due to heartbeat if any, are of substantially lower value than those associated with the low RF signal. The heart rate monitor includes a difference amplifier which effectively subtracts the doppler signal associated with the high RF frequency from the doppler signal associated with the low RF frequency to obtain a signal which contains only components due to the heartbeat of the patient.
90 Citations
9 Claims
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1. A heart rate monitor comprising in combination:
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first means for producing a first radio frequency (RF) signal at a relatively low frequency and for producing a second RF signal at a relatively high frequency; second means coupled to said first means and adapted for radiating signals therefrom toward a patient whose heart rate is to be measured and for receiving doppler shifted signals back from said patient at the frequencies of said first and second RF signals; third means for removing the respective RF frequencies from the returned signals leaving the doppler signal components thereof, said doppler signal associated with both RF signals containing signal components of the same values corresponding to patient movement due to respiration, the doppler signal associated with the low RF frequency containing characteristics associated with patient movement due to heartbeat; and fourth means for combining the two doppler signals to remove the components thereof which are common to both signals and thereby leaving the component of signal which is associated with heartbeat, the number of heartbeats per unit time corresponding to heart rate. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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Specification