How to make a signal more flat ?

Hello,

I have a signal which looks like a dome and I would like to make it flat (hence reducing its amplitude). I can reduce the amplitude by dividing the whole signal by the same amount, but I would like to be able to control the amount of reduction I do on each signal location. Any idea of what kind of operation i should use ?

Regards

Answer 1

[Image Analyst]

You can subtract the mean

newSignal = yourSignal - mean(yourSignal);

Then multiply by the array that contains the reduction factors that varies as a function of location:

flattenedSignal = reductionFactors .* newSignal;

Note, you must have reductionFactors because you said "I would like to be able to control the amount of reduction I do on each signal location" so you obviously know what those reductions are. Then finally add back in the mean:

finalSignal = flattenedSignal  + mean(yourSignal);

[scaramanga]

No I don't even have an "explicit" function to perform the reduction. I was thinking of computing it directly from the signal. The higher the amplitude is, the higher the reduction is, but I don't know how compute the reduction factor, that's what I'm asking actually...

[Miro]

this depends on the theoretical background of the data. I mean sure, you can just cut the signal fe. like:

ref = yoursignal/max(yoursignal);
newSignal = yoursignal*exp(-ref);

in this case larger signals get cutted more than smaller ones relative to the maximum of the signal.

[scaramanga]

@Miro : Your solution seems the closest from what I expect. I'm going to start from it and see where it does lead me.

Answer 2

[Miro]

you could use SMOOTH it provides a moving average, that makes a signal more continuous(flat)

Answer 3

[scaramanga]

It won't be enough. I give you a picture of my signal : http://www.imagup.com/data/1157449109.html, Basically I want that it fluctuates around ~0.35.