Subtract values from signal

[08anja]

Hi everybody, 

I do have signal that contains a high and a low level from LEDs when they are blicking. When the lights are off there comes some background noise from the ambient light which effects my signal when on. I would like to measure the values when low, and them subtract them from the values when on and use that for further calculations. Hopes it makes sense when you see the picture. 

I dont know if I should solve this with some kind of Samle & Hold function using Shift Register or what to do. 

Please share you ideas 

Thanks in advance. 

My signal usually looks something like this: 

FYI, it isnt just enough to comparise and only allowing values over a certain thredsholde to pass. Because the background noise needed to my subtracted from the high level signal.. 

[GerdW]

Hi anja,

why do you create double posts for the same questions? Stick with one thread!

This is quite irritating!