Heart rate monitor with cross talk reduction

• US 7,797,038 B2
• Filed: 08/07/2007
• Issued: 09/14/2010
• Est. Priority Date: 08/07/2007
• Status: Expired due to Fees

• Current Assignee: Salutron, Inc.
• Original Assignee: Salutron, Inc.
• Inventors: Lo, Thomas Ying-Ching, Hui, Chor Kuen Eddy
• Primary Examiner(s): Layno; Carl H
• Assistant Examiner(s): Kimball; Jeremiah T
• Application Number:
  US11/835,305
• Publication Number:
  US 20090043217A1
• Time in Patent Office: 1,134 Days
• Field of Search: 600/519
• US Class Current: 600/519
• CPC Class Codes: A61B 5/0002 Remote monitoring of patients using telemetry, e.g. transmission of vital signals via a communication network A61B5/07 takes precedence; transmission systems for measured values G08C; transmission H04B; transmission of digital information H04L; wireless communication networks H04W
• CPC Class Codes: A61B 5/02438 with portable devices, e.g. worn by the patient
• CPC Class Codes: A61B 5/0245 by using sensing means generating electric signals, i.e. ECG signals
• CPC Class Codes: A61B 5/681 Wristwatch-type devices

Abstract

A heart rate monitor determines a heart rate for a primary subject by reducing noise and cross-talk from unwanted signal transmission sources. A set of pulse peaks having about the same amplitude and an amplitude greater than any other set of peaks are processed to determine a subject'"'"'s heart rate, while data having an amplitude below that of the set of peaks is ignored. To retrieve enough data to determine a peak amplitude, the signal having heart rate information is sampled at a frequency higher than a normal sampling frequency. In some embodiments, if no data is received for a set time period which is in or above the range, the threshold resets to zero under an assumption that the primary subject is no longer within transmitting range.

Claims

1. A computer implemented method for determining a heart rate, comprising:

receiving wireless signals at a heart rate monitor, the wireless signals containing heart rate information of a primary user and at least one secondary user, the heart rate information of the at least one secondary user is unwanted cross-talk;

identifying a peak associated with one pulse of the wireless signals;

determining an amplitude of the peak associated with the one pulse;

deriving a threshold value from the amplitude of the peak associated with the one pulse;

identifying a peak associated with another pulse of the wireless signals;

determining an amplitude of the peak associated with the another pulse;

comparing the amplitude of the peak associated with the another pulse to the threshold value;

determining a heart rate of the primary user using information associated with the another pulse based on said step of comparing; and

displaying the heart rate of the primary user at the heart rate monitor.

2. The computer implemented method of claim 1, further comprising:

sampling the wireless signals at the heart rate monitor at a sampling frequency of between 10 KHz and 20 KHz, before the identifying the peak associated with the one pulse of the wireless signals and the identifying the peak associated with the another pulse of the wireless signals.

3. The computer implemented method of claim 2, wherein the sampling frequency is between 11 KHz and 15 KHz.

4. The computer implemented method of claim 1, wherein the wireless signals are received at the heart rate monitor from transmitters worn by the primary user and the at least one secondary user, the transmitters are within transmission range of the heart rate monitor.

5. The computer implemented method of claim 1, wherein the threshold value is in a range derived from the amplitude of the peak associated with the one pulse.

6. The computer implemented method of claim 1, wherein said step of determining a heart rate includes:

updating a current heart rate based on timing information for an occurrence of the peak associated with the another pulse.

7. The computer implemented method of claim 1, wherein:

the wireless signals include a number of peaks having a similar maximum amplitude; and

the threshold value is set based on the similar maximum amplitude.

8. The computer implemented method of claim 1, wherein said step of determining a heart rate includes:

determining that a time between the peak associated with the one pulse and the peak associated with the another pulse is within a time range threshold which is based on a current heart rate.

9. The computer implemented method of claim 1, wherein said step of determining a heart rate includes:

determining that the amplitude of the peak associated with the another pulse is less than the threshold value; and

not updating the heart rate using the peak associated with the another pulse.

10. The computer implemented method of claim 1, wherein said step of determining a heart rate includes:

determining that the amplitude of the peak associated with the another pulse is greater than the threshold value; and

revising the threshold value based on the amplitude of the peak associated with the another pulse.

11. The computer implemented method of claim 1, wherein one or more signal pulses which are in the wireless signals and which have peak amplitudes less than the threshold value are not used to determine the heart rate.

12. The computer implemented method of claim 1, wherein the heart rate monitor is incorporated into an exercising apparatus which is used by the primary user.

13. The computer implemented method of claim 1, wherein the wireless signals include a wireless signal from a transmitter worn by the primary user, and the heart rate monitor does not recognize the transmitter by encoding of the wireless signals.

14. The computer implemented method of claim 1, wherein:

the wireless signals are received from first and second transmitters, the first transmitter is part of an apparatus worn by the primary user which converts an EKG signal of the primary user into the one pulse, and the second transmitter is part of an apparatus worn by the at least one secondary user which converts an EKG signal of the at least one secondary user into the another pulse.

15. The computer implemented method of claim 1, wherein:

the one pulse and the another pulse each are modulated at 5 KHz and are between five to twenty milliseconds in length.

16. The computer implemented method of claim 1, further comprising:

processing the wireless signals by sampling, obtaining an absolute value, and obtaining a moving average, before the identifying the peak associated with the one pulse of the wireless signals and the identifying the peak associated with the another pulse of the wireless signals.

17. The computer implemented method of claim 1, wherein the wireless signals are not encoded based on a transmitter.

18. A computer implemented method for determining a heart rate, comprising:

receiving wireless signals at heart rate monitor circuitry, the wireless signals containing heart rate information of a primary user and heart rate information of at least one secondary user, the heart rate information of the at least one secondary user is unwanted cross-talk;

identifying one set of peaks associated with the wireless signals;

determining a highest-amplitude peak within the one set of peaks;

deriving a threshold value from an amplitude of the highest-amplitude peak within the one set of peaks;

identifying a subsequent peak associated with the wireless signals, the subsequent peak is after the one set of peaks;

determining an amplitude of the subsequent peak;

comparing the amplitude of the subsequent peak to the threshold value;

determining whether to update a heart rate of the primary user based on said step of comparing; and

displaying the heart rate of the primary user using the heart rate monitor circuitry.

19. The computer implemented method of claim 18, wherein the threshold value is in a range of threshold values which is based on the highest-amplitude peak within the one set of peaks.

20. The computer implemented method of claim 18, wherein said step of determining a heart rate includes:

updating the heart rate based on timing information for an occurrence of the subsequent peak.

21. The computer implemented method of claim 18, wherein said step of determining whether to update the heart rate includes:

determining whether a time between the highest-amplitude peak and the subsequent peak is within a time range threshold;

wherein the heart rate is updated using the subsequent peak when the time between the highest-amplitude peak and the subsequent peak is determined to be within the time range threshold, and the heart rate is not updated using the subsequent peak when the time between the highest-amplitude peak and the subsequent peak is determined to be outside the time range threshold.

22. The computer implemented method of claim 18, wherein said step of determining whether to update the heart rate includes:

comparing the amplitude of the subsequent peak to the threshold value;

wherein the heart rate is updated using the subsequent peak when the amplitude of the subsequent peak is determined to exceed the threshold value, and the heart rate is not updated using the subsequent peak when the amplitude of the subsequent peak is determined to be less than the threshold value.

23. The computer implemented method of claim 18, wherein said step of determining a heart rate includes:

determining that the amplitude of the subsequent peak is greater than the threshold value; and

updating the threshold value based on the amplitude of the subsequent peak in response to determining that the amplitude of the subsequent peak is greater than the threshold value.

24. The computer implemented method of claim 18, wherein one or more signal portions which are in the wireless signals and which have peak amplitudes less than the threshold value are not used to determine the heart rate.

25. The computer implemented method of claim 18, further comprising:

processing the wireless signals by sampling, obtaining an absolute value, and obtaining a moving average, before the identifying the highest-amplitude peak and the identifying the subsequent peak.

26. The computer implemented method of claim 18, wherein:

the wireless signals include a wireless signal from a transmitter which is worn by the primary user, and a wireless signal from a transmitter which is worn by the at least one secondary user.

27. The computer implemented method of claim 18, wherein:

the heart rate monitor circuitry is incorporated into an exercising apparatus which is used by the primary user.

28. The computer implemented method of claim 18, wherein:

the wireless signals include pulses modulated at 5 KHz and between five to twenty milliseconds in length.

29. The computer implemented method of claim 18, wherein:

the subsequent peak is identified as a highest-amplitude peak within a subsequent set of peaks which is after the one set of peaks.