Transtelephonic monitoring of multi-channel ECG waveforms
First Claim
Patent Images
1. A method of remotely monitoring at a central station cardiac conditions existing at a remote station, comprising:
- deriving three or more ECG waveforms at a local station and frequency modulating a respective carrier in accordance with each of said waveforms to thereby produce three or more respective FM signals;
combining the FM signals into a composite FM signal containing concurrent information from the three or more ECG waveforms;
transmitting the composite FM signal to a central station;
processing the composite FM signal received at the central station both in the time domain and in the frequency domain to reconstruct the three or more individual ECG waveforms.
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Abstract
Remote monitoring of biological signals such as ECG waveforms, in which an FM encoded version of an ECG waveform is transmitted from a patient'"'"'s home to a central station where it is analyzed to estimate local frequencies at many more time points than the zero crossovers of the FM signal. A plurality of ECG waveforms is encoded in a composite FM signal any one point of which can represent at the same time a number of ECG waveforms. The composite waveform is analyzed at the central station to extract and reconstruct the individual waveforms by separation in the frequency domain.
62 Citations
20 Claims
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1. A method of remotely monitoring at a central station cardiac conditions existing at a remote station, comprising:
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deriving three or more ECG waveforms at a local station and frequency modulating a respective carrier in accordance with each of said waveforms to thereby produce three or more respective FM signals;
combining the FM signals into a composite FM signal containing concurrent information from the three or more ECG waveforms;
transmitting the composite FM signal to a central station;
processing the composite FM signal received at the central station both in the time domain and in the frequency domain to reconstruct the three or more individual ECG waveforms. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method of reconstructing at a central station an ECG waveform derived at a remote station, comprising the steps of:
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deriving an ECG waveform at a remote station;
frequency modulating a carrier in accordance with the ECG waveform to generate an FM signal related to the ECG waveform and having zero crossovers;
transmitting the FM signal to a central station;
processing the FM signal at the central station to estimate local frequencies thereof at times occurring substantially more frequently than the zero crossovers of the FM signal; and
using the estimated local frequencies to reconstruct the ECG waveform at the central station. - View Dependent Claims (8, 9, 10, 11)
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12. A method of reconstructing an ECG waveform from an FM signal comprising a carrier that is frequency modulated with the ECG waveform, comprising:
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digitizing the FM signal into first time domain digital values representing local amplitudes of the FM signal;
converting the time domain digital values into frequency domain digital values representing content of the FM signal at respective frequencies within a band of interest for said ECG waveform;
generating a phase-shifted version of the frequency domain digital values;
converting the frequency domain digital values and the phase-shifted version thereof to respective second and third time-domain digital values;
using said second and third time domain digital values to calculate local frequencies at locations in said FM signal corresponding to at least twice the carrier frequency; and
using said local frequencies to reconstruct said ECG waveform. - View Dependent Claims (13, 14, 15)
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16. A method of reconstructing a plurality of ECG waveforms from a composite FM signal formed by combining a plurality of carriers FM encoded with respective ones of the ECG waveforms such that a time slot of the composing signal contains information from each of a plurality the ECG waveforms, said composite waveforms having zero crossovers, comprising the steps of:
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digitizing the composite signal;
processing the composite signal in the digital domain to estimate local frequencies thereof at times occurring substantially more frequently that said zero crossovers; and
using the estimated local frequencies to reconstruct said ECG waveforms. - View Dependent Claims (17, 18, 19, 20)
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Specification