Denoising real-time analog signals

[gathanokos]

Hello,

I'm very new to signal processing and was wondering if I would be able to smooth out the signal I am getting from a flowmeter.

The figure is the current state of my signal.

As you can see, there is a sinusoidal tendency where the average value is somewhere around 1.

However, there is too much noise in the signal, and I want to filter it out to have a smooth signal coming out so that afterwards I can feed it into my controller.

I've tried fiddling with the WA denoise VI but it doesn't change the signal at all.

The filters don't work as well, so I'm guessing I'm not using them correctly or they are not used for this purpose.

Can I get some insight of what I should do to make the noisy signal into a smooth signal?

Thank you.

[Kyle97330]

You have what appears to be a lower frequency signal you want to isolate while removing high frequency noise, so it's likely the type of filter you want is a "low pass" filter, meaning it's a filter that lets lower frequency signals pass while filtering higher frequency ones.

I would recommend you try a low pass Butterworth filter and see how close that gets you to what you want with your signal.  You will probably have to tweak the input parameters of the filter to get something useful out of it.

Example:

Note that doing any sort of filtering will add a delay to your output, so be wary of that if you're feeding this back into something.  You don't want to delay it so much that it's no longer an accurate reading.

[altenbach]

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@gathanokos wrote:

As you can see, there is a sinusoidal tendency where the average value is somewhere around 1.

However, there is too much noise in the signal, and I want to filter it out to have a smooth signal coming out so that afterwards I can feed it into my controller.

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So what exactly is the signal you are trying to isolate? What is your definition of a "smooth signal"?

1. The constant average of around 1?
2. The amplitude, phase, and frequency of the sinusoidal signal? I cannot really read your x-axis, but what is the frequency? Is that an interesting signal or a 50Hz/60Hz artifact from the AC power?
3. Something else?
4. How do you read the data (1 point at a time? hardware timed buffered continuous?)
5. What does the controller do with it?