Waveform smoothing

[Dhans]

Hi, all I am doing now pulse oximeter project in labview. I have got signals from oximeter and waveform is generated in waveform graph. But not a smooth one. I need a smooth waveform like the image attached here. What are the applicable methods to solve this problem?

[Tim_S]

There is a whole subpallet labeled "Filters" under Signal Processing that are applicable, and that's really only a subset of what is out in the world. To know which filter(s) you want to use, you need to identify what you want to get rid of first. Not all filters are equal. Some maintain amplitude, but shift phase. Others are designed to maintain phase at the cost of amplitude. Each one has its use. So the method to solve the problem is to identify what you want to keep and what you want to filter out, then select one or more filters that do that.

If you want some assistance in picking filters, then you're going to have to provide some additional information about your raw data.

[GregSands]

Tim's right in that you need to provide a lot more information - the appropriate filters and parameters are very dependent on the raw data.

Having said that, for the purpose you describe (which I'm guessing is signal visualization rather than signal analysis) the first filter I will tend to try is the Savitzky-Golay filter, though again the parameters can be quite sensitive.  It's essentially a piece-wise polynomial fit.  There is also a Pt-by-Pt version which is useful for real-time data processing as it is acquired.

[Jordan Kuehn]

Shooting in the dark here as well, but I would start with just a moving average at first...