Electrocardiogram baseline removal
A system includes a low pass-filter and a Savitzky-Golay filter. The low-pass filter receives and processes a first electrocardiogram signal. The filter removes at least the high frequency components of the first electrocardiogram signal. The Savitzky-Golay filter estimates a baseline variation of the first electrocardiogram signal from the filtered first electrocardiogram signal. Related apparatus, systems, techniques and articles are also described.
1. A system comprising:
a low-pass filter configured to receive and process a first electrocardiogram signal, the low-pass filter removing at least high frequency components of the first electrocardiogram signal thereby producing a filtered first electrocardiogram signal;
a down-sampler configured to reduce a sampling rate of the filtered first electrocardiogram signal;
a Savitzky-Golay filter configured to estimate a baseline variation of the first electrocardiogram signal from the down-sampled filtered first electrocardiogram signal;
an up-sampler configured to increase a sampling rate of the baseline variation;
a delay module configured to time shift the first electrocardiogram signal thereby producing a time shifted first electrocardiogram signal; and
a combination module configured to combine the time shifted first electrocardiogram signal and the up-sampled baseline variation thereby producing a second electrocardiogram signal with the baseline variation removed;
wherein the second electrocardiogram signal is provided by at least one of displaying the second electrocardiogram signal in an electronic visual display, transmitting the second electrocardiogram signal to a remote computing system, storing the second electrocardiogram signal in a physical storage media, or loading the second electrocardiogram signal into memory.
2. The system of claim 1 , where the low-pass filter has a cutoff frequency of 0.8 hertz.
3. The system of claim 1 , wherein the first electrocardiogram signal is sampled at a rate of 500 hertz.
4. The system of claim 1 , wherein a polynomial degree of the Savitzky-Golay filter is between 2 and 10.
5. The system of claim 1 , wherein a window size of the Savitzky-Golay filter is less than 750.
6. The system of claim 1 , wherein the down-sampler reduces the sample rate of the filtered first electrocardiogram signal by a factor of 40 and the up-sampler increases the sample rate of the baseline variation by a factor of 40.
7. The system of claim 1 , wherein the up-sampler performs linear interpolation.
8. A method comprising:
receiving a first electrocardiogram signal;
processing the first electrocardiogram signal in a filter thereby removing at least high frequency components of the first electrocardiogram signal, producing a filtered first electrocardiogram signal;
down-sampling the filtered first electrocardiogram signal;
processing the down-sampled filtered first electrocardiogram signal in a Savitzky-Golay filter to estimate a baseline variation of the first electrocardiogram signal;
up-sampling the baseline variation;
delaying the first electrocardiogram signal, producing a time shifted first electrocardiogram signal; and
combining the time shifted first electrocardiogram signal and the up-sampled baseline variation, producing a second electrocardiogram signal with the baseline variation removed
providing the second electrocardiogram signal by at least one of displaying the second electrocardiogram signal in an electronic visual display, transmitting the second electrocardiogram signal to a remote computing system, storing the second electrocardiogram signal in a physical storage media, or loading the second electrocardiogram signal into memory.
9. The method of claim 8 , wherein at least the frequencies above 0.8 hertz are removed from the received first electrocardiogram signal.
10. The method of claim 8 , wherein the received first electrocardiogram signal has been sampled at a rate of 500 hertz.
11. The method of claim 8 , wherein a polynomial degree of the Savitzky-Golay filter is between 2 and 10.
12. The method of claim 8 , wherein a window size of the Savitzky-Golay filter is less than 750.
13. A system comprising:
at least one data processor;
memory storing instructions which, when executed by the at least one data processor, cause the at least one data processor to perform operations comprising:
receiving a first electrocardiogram signal;
processing the first electrocardiogram signal in a filter thereby removing at least high frequency components of the first electrocardiogram signal, producing a filtered first electrocardiogram signal;
down-sampling the filtered first electrocardiogram signal;
processing the down-sampled filtered first electrocardiogram signal in a Savitzky-Golay filter to estimate a baseline variation of the first electrocardiogram signal;
up-sampling the baseline variation;
delaying the first electrocardiogram signal, producing a time shifted first electrocardiogram signal; and
combining the time shifted first electrocardiogram signal and the up-sampled baseline variation, producing a second electrocardiogram signal with the baseline variation removed,
providing the second electrocardiogram signal by at least one of displaying the second electrocardiogram signal in an electronic visual display, transmitting the second electrocardiogram signal to a remote computing system, storing the second electrocardiogram signal in a physical storage media, or loading the second electrocardiogram signal into memory.
14. The system of claim 13 , wherein at least the frequencies above 0.8 hertz are removed from the received first electrocardiogram signal.
15. The system of claim 13 , wherein the received first electrocardiogram signal has been sampled at a rate of 500 hertz.
16. The system of claim 13 , wherein a polynomial degree of the Savitzky-Golay filter is between 2 and 10.
17. The system of claim 13 , wherein a window size of the Savitzky-Golay filter is less than 750.