ECG recorder and playback unit
First Claim
1. A method for obtaining corrected ECG data in a system comprising a recorder and a playback unit, said method comprising the steps of:
- dynamically measuring a system frequency response of said system;
deriving a correction filter response from the system frequency response and a predetermined desired response;
recording ECG data with said recorder, thereby creating recorded ECG data;
filtering said recorded ECG data according to the correction filter response, thereby creating said corrected ECG data; and
outputting said corrected ECG data.
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Accused Products
Abstract
An ECG recorder and playback unit which includes software-implemented digital signal processing filters which compensate for phase and magnitude distortion occurring when an ECG signal is recorded on a Holter recorder and played back. This permits "tuning" a recorder and playback unit which may be unrelated, as when made by different manufacturers. An impulse or step signal is recorded and played back to provide a system frequency response measurement. Coefficients for a digital correction filter are derived from the discrete Fourier transform of the impulse or step response and a desired system response. When recorded ECG data is played back, it is filtered on a substantially real-time basis with the digital correction filter to compensate for phase and magnitude distortion. Prior to recording, the high frequencies of the ECG signal are boosted to compensate for high frequency losses inherent in the recording and playing back of ECG signals. A calibration pulse and a system characterization pulse are derived by statistically selecting from a plurality of pulses and averaging the selected pulses in order to minimize the effects of noise and tape defects in the pulses. High frequency components of the ECG signal can be amplified prior to recording the signal. This results in decreased amplification, and therefore noise, when the recorded signals are played back. Cardiac pacer pulse detection is performed prior to the step of filtering the played back signal to optimize pulse detection.
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Citations
33 Claims
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1. A method for obtaining corrected ECG data in a system comprising a recorder and a playback unit, said method comprising the steps of:
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dynamically measuring a system frequency response of said system; deriving a correction filter response from the system frequency response and a predetermined desired response; recording ECG data with said recorder, thereby creating recorded ECG data; filtering said recorded ECG data according to the correction filter response, thereby creating said corrected ECG data; and
outputting said corrected ECG data. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. An ECG recorder and playback system for obtaining corrected ECG data, comprising:
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means for dynamically measuring a system frequency response of said system; means for deriving a correction filter response from the system frequency response and a predetermined desired response; means for recording ECG data with said recorder, thereby creating recorded ECG data; means for filtering said recorded ECG data according to the correction filter response, thereby creating said corrected ECG data; and means for outputting said corrected ECG data. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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27. A system for obtaining corrected ECG data, comprising:
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an ECG recorder for recording ECG data, thereby creating recorded ECG data; a playback unit, comprising; a playback transport having an output for playing back said recorded ECG data; an amplifier having an input coupled to the output of the playback transport and an output for providing amplified ECG data; a correction filter having an input coupled to the amplifier output, an output for providing corrected ECG data, said correction filter responsive to a dynamically measured system frequency response of said system and a predetermined desired response of said system; and a printer for printing said corrected ECG data. - View Dependent Claims (28, 29, 30, 31, 32, 33)
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Specification