Device for filtering ECG signals
First Claim
1. A device for filtering analog ECG signals for use with a source of said ECG signals comprising:
- filter means, having inputs supplied with analog ECG signals, for filtering out components of said ECG signals, said filter means having an amplitude characteristic and a phase response, and producing filtered ECG signals;
an analog-to-digital converter, having inputs and to which said filtered ECG signals are supplied, and which converts said filtered ECG signals into an output signal consisting of a series of successive digital values corresponding to said filtered ECG signals at said inputs at successive times, said output signal exhibiting differing frequency contents at different times; and
high-pass filter means, to which said output signal from said analog-to-digital converter is supplied for forward filtration only, having an amplitude characteristic and a non-linear phase response with a frequency passband, a suppressed frequency band and a transition band between said passband and said suppressed frequency band, for delaying an output signal from said analog-to-digital converter with a frequency in said passband more than an output signal from said analog-to-digital converter with a frequency in said transition band, said amplitude characteristic of said high-pass filter means being the same as the amplitude characteristic of said filter means, and said phase response of said high-pass filter means being opposite to the phase response of said filter means.
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Accused Products
Abstract
A device for filtering ECG signals has an A/D converter and a filter unit connected to the converter'"'"'s output. The filter unit includes a filter, or a combination of filters with a non-linear phase response such that signals with frequencies in the passband of the filter, or the combination of filters, are delayed more than signals with frequencies in the transition band between the passband and the suppressed frequency band of the filter, or the combination of filters. A method for producing an FIR filter, with a phase response opposite to the phase response of a filter for filtering out DC components, or an IIR filter, suitable for use in the above-described device, is also disclosed in which the impulse response from the filter for filtering out DC components and low-frequency components or the IIR filter is reversed in time and sampled. The sampled values are then used for determining coefficients for the FIR filter.
66 Citations
11 Claims
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1. A device for filtering analog ECG signals for use with a source of said ECG signals comprising:
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filter means, having inputs supplied with analog ECG signals, for filtering out components of said ECG signals, said filter means having an amplitude characteristic and a phase response, and producing filtered ECG signals; an analog-to-digital converter, having inputs and to which said filtered ECG signals are supplied, and which converts said filtered ECG signals into an output signal consisting of a series of successive digital values corresponding to said filtered ECG signals at said inputs at successive times, said output signal exhibiting differing frequency contents at different times; and high-pass filter means, to which said output signal from said analog-to-digital converter is supplied for forward filtration only, having an amplitude characteristic and a non-linear phase response with a frequency passband, a suppressed frequency band and a transition band between said passband and said suppressed frequency band, for delaying an output signal from said analog-to-digital converter with a frequency in said passband more than an output signal from said analog-to-digital converter with a frequency in said transition band, said amplitude characteristic of said high-pass filter means being the same as the amplitude characteristic of said filter means, and said phase response of said high-pass filter means being opposite to the phase response of said filter means. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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Specification