Questions about Stimulus-Probe and Fixed point filter table generator on ADAU1787

SigmaDSP & SigmaStudio Yosen Oct 23, 2019 00:00 1 replies Original on forum ↗

Yosen Question

Oct 23, 2019 00:00

Hi guys

Serval customers are wondering how to stimulate the frequency response of the Filters on ADAU1787. I suppose the Stimulus-Probe functions of SigmaStudio may be helpful. However, when I try to simulate the filters, I've got no output in the Probe. Shown as the screen shot as below:

However, when I reduce the order of my IIR filters and simulate again. Then I can see the output in the Probe, shown as below:

I am not sure if there are limitations I don't know of the Simulate-Probe functions. Or I just do not use it in a correct way. please help to check about it. if I need to upload the project, please let me know.

And I also find that we can provide a fixed point filter table generator in SigmaStudio.

I am wondering if this tool can help us to design the IIR filters for noise cancellation. How can I design a high order IIR filters(5-order biquad and maybe more) with this tool?

I am appreciate if you can share your thoughts and experience.

B.R.

Yosen

ADAU1787

Integrated/Special Purpose A/D Converters

adau1777

Audio CODECs

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DaveThib Reply

Nov 5, 2019 00:00

Hello Yosen,

Please upload your project. You have to Zip it first.

I am surprised that it did not work until you reduced the order of the filters. I would like to investigate.

Often what the problem is regarding the Stimulus and Probe is when the coefficients for the filter is realized in the core rather than in SigmaStudio. Then the tool does not know what the coefficients are and so cannot produce the filter curve.

For instance, This happens when you use an index controlled filter. SigmaStudio does not know what is running in the core so it cannot choose the index.

Then there are the filters that the SigmaDSP actually calculates the coefficients. Again, SigmaStudio has no idea what the filter in the core is doing. The earlier SigmaDSP cores were not able to calculate their own coefficients so the tool worked better with the exception of the index controlled filters. Now with the Sigma300 core it is getting more difficult for this Stimulus and Probe feature to work.

Regarding your noise cancellation question. Are you aware that we have a AEC/NR algorithm designed and available? It is under license but there are demo versions in SigmaStudio. There are examples as well on the Wiki. Contact me for more details.

Thanks,

Dave T

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