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GMartin · Joined: Feb 5, 2010 Posts: 229

Jarek,

I have been working with the dominant frequency element and have a question
Where in that element can I change the number of Bins used in the calculation?

Thanks

George

jarek · Joined: Oct 22, 2007 Posts: 698

It is: "FFT bin count"

If the above value is larger than "Input sample count" then the reminding values are filled with 0.

Smaller "Input sample count" improves response time, but degrades accuracy.

GMartin · Joined: Feb 5, 2010 Posts: 229

Thanks

GMartin · Joined: Feb 5, 2010 Posts: 229

I have used that on the FFT transform but can not find that option in the FFT2 transform used inthe dominant frequency calculation.

George

jarek · Joined: Oct 22, 2007 Posts: 698

FFT2Transform doesn't do windowing. It uses a separate element for that: StreamToVector2.

GMartin · Joined: Feb 5, 2010 Posts: 229

Jarek,

I have noticed that the dominant frequency output value slows down over time,after about 10 seconds or so the value slowly. If I set a numeric display to six digits I can see some changes in the 5th and 6th digits. I have tried this with a variety of edf files with the same results

I have experimented with different values in the streamtovector2 with no real success. One of the versions I tried updated more quickly and continued over to do that over time but the values were clearly not accurate.

Is there a way to fine tune the dominant frequency nested design to make it respond more quickly

Any help is greatly appreciated, signal processing is not my strength.

Thanks

George

jarek · Joined: Oct 22, 2007 Posts: 698

Try lowering the value of "Input sample count"

The lower it is, the faster the response should be.

For example, with input sample rate of 256, if you set it to 128, you should have a response of about half a second.

GMartin · Joined: Feb 5, 2010 Posts: 229

Thanks

This accomplishes exactly what I want