bug for frequency response calculation ?

Hello Power Pan,

Which processor are you using?

What revision of SigmaStudio?

Which EQ block are you using?

Where did that design window come from? You ask how do you see it but then it is open and you can see it. So I do not know what you are asking about?

Dave T

Hello Dave:

thanks for your reply. I deleted a reply in the middle by mistake so that some information were missed. sorry for that.

1. ADAU1452

2. 4.5.1 beta

3. parametric EQ

but regardless above specs, the EQ windows should not show difference between the probe and the PEQ, that's why I put the question there.

the design window is I saw from another reply, I could not find it. so I need guide, that's why I asked.

Hello PowerPan,

I am tight on time, can you send me the project so I can save some time trying to set this up?

Send it in a PM if you do not want to post it here. You have to zip up the project first.

Thanks,

Dave T

Hello PowerPan and Dave,

Re the design window that PowerPan is looking for -- it's the Fixed Point Filter Table Generator found in SigmaStudio's Tools menu. It lets you plot a family of curves for a set of related filters, then it calculates the IIR coefficients for each of the curves.

Best regards,

Bob

Hello, Bob

thanks for your kind reply. got it. sometimes a little bit hard to find a module like parametric EQ, that's not in the filter->miscellaneous, but in filter->second order->double precision->no slew... cause the document in the website is not up to date. no matter what, sigma-studio is a great CAD that bring us lots of funs.

Best regards,

Power Pan

Hello Dave

attached is the file

test_filter.zip

Finally I figured out that what's wrong, please note that below IIR table, A1/A2, I think there should be something wrong with the symbol

when A1=-A1 and A2=-A2, then PEQ window is ok, and the chip works fine.

but when use the equation from the FilterMathCalculations.pdf or the result from 1st-2nd-order_iir_coefficient_calculator.xls, it goes wrong.

so, am I did something wrong ? or it's a bug or it's designed as is?

hope somebody could give me a reply/