convert direct form filters to SOS DF2 form

Hi Everyone,

I know that MATLAB can convert direct form filters to biquads/SOS DF2 form. I wanted to know if there are any other softwares which can do that.

Kindly let me know if anyone knows about any other software.

Thanking You
Megha

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Megha-

> I know that MATLAB can convert direct form filters to biquads/SOS DF2 form.
> I wanted to know if there are any other softwares which can do that.
>
> Kindly let me know if anyone knows about any other software.

If the MATLAB function to which you are referring is given only arbitrary
coefficients, and knows nothing about the original design method, then it's
performing factoring to find the 2nd order sections. If that's what you want, then
you can search for software that is capable of factoring, finding roots/zeros, etc.

But it may not be what you want. In your application, do you know the original
design method and filter parameters? If so, then you can "back up one step" to find
the 2nd order sections.

-Jeff Start a New Thread

Hi Jeff,

Thanks fo rthe reply.
I am calculating the direct form filters using MATLAB (cheby2). So now I have Num and Den for the IIR filter and I want to find the biquads. I am using "tf2sos" to get biquads. I want to use some other software to confirm these.

Thanks,
Megha

Jeff Brower wrote:
Megha-

> I know that MATLAB can convert direct form filters to biquads/SOS DF2 form.
> I wanted to know if there are any other softwares which can do that.
>
> Kindly let me know if anyone knows about any other software.

If the MATLAB function to which you are referring is given only arbitrary
coefficients, and knows nothing about the original design method, then it's
performing factoring to find the 2nd order sections. If that's what you want, then
you can search for software that is capable of factoring, finding roots/zeros, etc.

But it may not be what you want. In your application, do you know the original
design method and filter parameters? If so, then you can "back up one step" to find
the 2nd order sections.

-Jeff Start a New Thread

Megha-

> Thanks fo rthe reply.
> I am calculating the direct form filters using MATLAB (cheby2). So now I have Num and Den for the IIR filter and I
> want to find the biquads. I am using "tf2sos" to get biquads. I want to use some other software to confirm these.

Well, you could use other filter design software to design an identical Chebyshev II filter and compare the biquads
that come out of it. I searched "online filter design" in Google and several sites came up that look promising.

Also, if you give me your filter specs, I'll put them in to Hypersignal software and give you back the filter
coefficient file (which has num and den in 2nd order section format).

-Jeff

> Jeff Brower wrote:
> Megha-
>
>> I know that MATLAB can convert direct form filters to biquads/SOS DF2 form.
>> I wanted to know if there are any other softwares which can do that.
>>
>> Kindly let me know if anyone knows about any other software.
>
> If the MATLAB function to which you are referring is given only arbitrary
> coefficients, and knows nothing about the original design method, then it's
> performing factoring to find the 2nd order sections. If that's what you want, then
> you can search for software that is capable of factoring, finding roots/zeros, etc.
>
> But it may not be what you want. In your application, do you know the original
> design method and filter parameters? If so, then you can "back up one step" to find
> the 2nd order sections.
>
> -Jeff Start a New Thread