Removing noise by superimposing quasi periodic bio-medical signals

Hi everyone,

I'm fairly new to signal processing. I'm doing a project which involves using matlab to superimpose quasi periodic bio-medical signals (emg or egg signals) to remove the noise (the noise approaches zero because its mean is zero) so I can calculate the signal to noise ratio (SNR). The problem is that I think the frequency changes over time (quasi periodic) so I don't know how to superimpose them. Is there a way to superimpose signals with different frequencies to cancel noise or is there an algorithm to change frequencies. How should I do it? I'm very confused. Thanks in advance.
John

Not fully understanding what you require, I would suggest you look at a tracking method if the frequency is changing during the test duration. There will be transitions as the frequency changes and the only way I can think of is to actively track the frequency as is done in active-noise-cancelling headphones. Only then will you be able to ascertain any SNR.

I cannot see it being done in something like Matlab unless you can create a script to follow the frequency and that sounds like a very complex undertaking to me.

But, then, I have been wrong before. :)

John,

Looks like homework and a lack of understanding of the process.

You can't remove noise from a signal by what you say you are trying to do.
It would remove the signal as well. And your S/N will = 0/0

So, I suggest you get a better understanding of signal processing and spectra to attack the noise.

The problem has no place on this forum.