Hi all,
I am working on baseline wander noise removal from ECG signal. I have to
compare the performance of different algorithms. for comparison I have to
use SNR. My question is how to calculate noise and signal power of an ECG
signal available in the data set. I do not know what kind of noise is there
in the ECG signal.
I have tried like this:
1. Filter the ECG signal with a basic filter to remove the baseline wander
signal. Then this signal is considered as Ideal signal (pure signal).
2. Then I have applied the devised algorithm to the original ECG signal.
So the output from the algorithm has,
output = signal + noise;
noise = ideal - output (using the algorithm)
signal = output - noise;
using this i have calculated the SNR. Is it acceptable...? Please help!!
Best,
Jebaraj S.Peter
SNR for ECG signal
Started by ●August 8, 2011
Reply by ●August 8, 20112011-08-08
Jebarajpeter wrote:> Hi all, > I am working on baseline wander noise removal from ECG signal. I have to > compare the performance of different algorithms. for comparison I have to > use SNR. My question is how to calculate noise and signal power of an ECG > signal available in the data set. I do not know what kind of noise is there > in the ECG signal. > > I have tried like this: > > 1. Filter the ECG signal with a basic filter to remove the baseline wander > signal. Then this signal is considered as Ideal signal (pure signal). > 2. Then I have applied the devised algorithm to the original ECG signal. > So the output from the algorithm has, > output = signal + noise; > noise = ideal - output (using the algorithm) > signal = output - noise; > using this i have calculated the SNR. Is it acceptable...? Please help!! > > Best, > Jebaraj S.Peter > > >
Reply by ●August 8, 20112011-08-08
Reply by ●August 8, 20112011-08-08
On Mon, 08 Aug 2011 10:45:22 -0500, Jebarajpeter wrote:> Hi all, > I am working on baseline wander noise removal from ECG signal. I have to > compare the performance of different algorithms. for comparison I have > to use SNR. My question is how to calculate noise and signal power of an > ECG signal available in the data set. I do not know what kind of noise > is there in the ECG signal. > > I have tried like this: > > 1. Filter the ECG signal with a basic filter to remove the baseline > wander signal. Then this signal is considered as Ideal signal (pure > signal). 2. Then I have applied the devised algorithm to the original > ECG signal. So the output from the algorithm has, > output = signal + noise; > noise = ideal - output (using the algorithm) signal > = output - noise; > using this i have calculated the SNR. Is it acceptable...? Please help!!Because an ECG signal is either non-stationary or non-Gaussian, or perhaps both, it's hard to express "SNR". Is this the measure that clinicians use to rate the quality of their ECG signals? If not, what is? If there is an alternative that's accepted, why not use it? -- www.wescottdesign.com
Reply by ●August 8, 20112011-08-08
Tim Wescott wrote:> Because an ECG signal is either non-stationary or non-Gaussian, or > perhaps both, it's hard to express "SNR". Is this the measure that > clinicians use to rate the quality of their ECG signals? If not, what > is? If there is an alternative that's accepted, why not use it?There is aproximately a zillion of ECG analysers of all sorts around. A megatonn of paperwork is written about it. Another ECG processor is just what the world needs. Medics are interested in the so-called "QRS complex" parameters calculated from the ECG data. The quality of ECG is the accuracy of the QRS measurement. How do I know about this? Because I wrote a math part for a [zillion-1] ECG processor :-) Vladimir Vassilevsky DSP and Mixed Signal Design Consultant http://www.abvolt.com
Reply by ●August 10, 20112011-08-10
On Aug 8, 11:45�am, "Jebarajpeter" <jebarajselvapeter.p@n_o_s_p_a_m.jasmin-infotech.com> wrote:> Hi all, > I am working on baseline wander noise removal from ECG signal. I have to > compare the performance of different algorithms. for comparison I have to > use SNR. My question is how to calculate noise and signal power of an ECG > signal available in the data set. I do not know what kind of noise is there > in the ECG signal. > > I have tried like this: > > 1. Filter the ECG signal with a basic filter to remove the baseline wander > signal. Then this signal is considered as Ideal signal (pure signal). � > 2. Then I have applied the devised algorithm to the original ECG signal. > So the output from the algorithm has, > � � � � � � � � � � �output = signal + noise; > � � � � � � � � � � �noise = ideal - output (using the algorithm) > � � � � � � � � � � �signal = output - noise; > using this i have calculated the SNR. Is it acceptable...? Please help!! > > Best, > Jebaraj S.PeterBefore you dig into this, find out whay the baseline wanders. Ideally, you will remove the cause instead of remedying the effect. In any event, you will know what you are contending with, always a good approach to a problem. Jerry -- Engineering is the art of making what you want from things you can get.
Reply by ●August 10, 20112011-08-10
On Aug 9, 5:17�am, Vladimir Vassilevsky <nos...@nowhere.com> wrote:> Jebarajpeter wrote: > > Hi all, > > I am working on baseline wander noise removal from ECG signal. I have to > > compare the performance of different algorithms. for comparison I have to > > use SNR. My question is how to calculate noise and signal power of an ECG > > signal available in the data set. I do not know what kind of noise is there > > in the ECG signal. > > > I have tried like this: > > > 1. Filter the ECG signal with a basic filter to remove the baseline wander > > signal. Then this signal is considered as Ideal signal (pure signal). � > > 2. Then I have applied the devised algorithm to the original ECG signal. > > So the output from the algorithm has, > > � � � � � � � � � � �output = signal + noise; > > � � � � � � � � � � �noise = ideal - output (using the algorithm) > > � � � � � � � � � � �signal = output - noise; > > using this i have calculated the SNR. Is it acceptable...? Please help!! > > > Best, > > Jebaraj S.Peterata boy - go Vlad...
Reply by ●August 11, 20112011-08-11
>On Aug 8, 11:45=A0am, "Jebarajpeter" ><jebarajselvapeter.p@n_o_s_p_a_m.jasmin-infotech.com> wrote: >> Hi all, >> I am working on baseline wander noise removal from ECG signal. I haveto>> compare the performance of different algorithms. for comparison I haveto>> use SNR. My question is how to calculate noise and signal power of anECG>> signal available in the data set. I do not know what kind of noise isthe=>re >> in the ECG signal. >> >> I have tried like this: >> >> 1. Filter the ECG signal with a basic filter to remove the baselinewande=>r >> signal. Then this signal is considered as Ideal signal (pure signal).=A0>> 2. Then I have applied the devised algorithm to the original ECGsignal.>> So the output from the algorithm has, >> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0output =3D signal + noise; >> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0noise =3D ideal - output(usin=>g the algorithm) >> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0signal =3D output - noise; >> using this i have calculated the SNR. Is it acceptable...? Pleasehelp!!>> >> Best, >> Jebaraj S.Peter > >Before you dig into this, find out whay the baseline wanders. Ideally, >you will remove the cause instead of remedying the effect. In any >event, you will know what you are contending with, always a good >approach to a problem. > >JerryYou want him to paralyse the patient? :-) ECG traces wander due to muscle noise - i.e. the muscles other than the heart's. Steve
Reply by ●August 11, 20112011-08-11
On Aug 11, 3:40�am, "steveu" <steveu@n_o_s_p_a_m.coppice.org> wrote:> >On Aug 8, 11:45=A0am, "Jebarajpeter" > ><jebarajselvapeter.p@n_o_s_p_a_m.jasmin-infotech.com> wrote: > >> Hi all, > >> I am working on baseline wander noise removal from ECG signal. I have > to > >> compare the performance of different algorithms. for comparison I have > to > >> use SNR. My question is how to calculate noise and signal power of an > ECG > >> signal available in the data set. I do not know what kind of noise is > the= > >re > >> in the ECG signal. > > >> I have tried like this: > > >> 1. Filter the ECG signal with a basic filter to remove the baseline > wande= > >r > >> signal. Then this signal is considered as Ideal signal (pure signal). > =A0 > >> 2. Then I have applied the devised algorithm to the original ECG > signal. > >> So the output from the algorithm has, > >> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0output =3D signal + noise; > >> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0noise =3D ideal - output > (usin= > >g the algorithm) > >> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0signal =3D output - noise; > >> using this i have calculated the SNR. Is it acceptable...? Please > help!! > > >> Best, > >> Jebaraj S.Peter > > >Before you dig into this, find out why the baseline wanders. Ideally, > >you will remove the cause instead of remedying the effect. In any > >event, you will know what you are contending with, always a good > >approach to a problem. > > >Jerry > > You want him to paralyse the patient? :-) ECG traces wander due to muscle > noise - i.e. the muscles other than the heart's. > > SteveSee? It's always good to know what one is contending with. :-) Jerry -- Engineering is the art of making what you want from things you can get.
Reply by ●May 3, 20142014-05-03
On Thursday, 11 August 2011 16:40:35 UTC+1, Jerry Avins wrote:> On Aug 11, 3:40�am, "steveu" <steveu@n_o_s_p_a_m.coppice.org> wrote: > > >On Aug 8, 11:45=A0am, "Jebarajpeter" > > ><jebarajselvapeter.p@n_o_s_p_a_m.jasmin-infotech.com> wrote: > > >> Hi all, > > >> I am working on baseline wander noise removal from ECG signal. I have > > to > > >> compare the performance of different algorithms. for comparison I have > > to > > >> use SNR. My question is how to calculate noise and signal power of an > > ECG > > >> signal available in the data set. I do not know what kind of noise is > > the= > > >re > > >> in the ECG signal. > > > > >> I have tried like this: > > > > >> 1. Filter the ECG signal with a basic filter to remove the baseline > > wande= > > >r > > >> signal. Then this signal is considered as Ideal signal (pure signal). > > =A0 > > >> 2. Then I have applied the devised algorithm to the original ECG > > signal. > > >> So the output from the algorithm has, > > >> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0output =3D signal + noise; > > >> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0noise =3D ideal - output > > (usin= > > >g the algorithm) > > >> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0signal =3D output - noise; > > >> using this i have calculated the SNR. Is it acceptable...? Please > > help!! > > > > >> Best, > > >> Jebaraj S.Peter > > > > >Before you dig into this, find out why the baseline wanders. Ideally, > > >you will remove the cause instead of remedying the effect. In any > > >event, you will know what you are contending with, always a good > > >approach to a problem. > > > > >Jerry > > > > You want him to paralyse the patient? :-) ECG traces wander due to muscle > > noise - i.e. the muscles other than the heart's. > > > > Steve > > See? It's always good to know what one is contending with. :-) > > Jerry > -- > Engineering is the art of making what you want from things you can get.Measure your noise in the in ST segmentof the ECG. This is stationary for approx 50mS. So take a window of 30mS in the middle of the S-T and add up all the data samples and find the standard deviation. Measure the signal across the QRS postion of the ECG...approx 120mS. Do the same with the data points. Divide the signal Std by the Noise Std. Job done.
