Re: Is there a way to change the number of taps of the FIR filter in GNURadio while running?

[Jay Patel]

Hi Marcus,

Thanks for your response. I tried your suggestions, but unfortunately while i changed the value of cutoff and transition width at runtime, it didn't change the filter response. 

See the attached image. This is very strange.

Am I missing something?

Thanks for your help.

With Regards,

Jay Patel

On Wed, Mar 3, 2021 at 11:26 PM Marcus D. Leech <patchvonbraun@gmail.com> wrote:

On 03/03/2021 10:10 PM, Jay Patel wrote:

Hi all,

I am using GNURadio example Filter Introduction flow graph which shows basic introduction of filtering. I want to change the no. of taps while running the program. I tried to put the qt gui range but it looks like GNURadio creates/calculates taps as a static vector in the start of the execution of the flow graph.

Is there a work around this ?  I mean can I put a slider or counter for changing the transition_width which changes the number of taps while running the flow graph ?

Thanks. Any suggestions are appreciated.

With Regards,

Jay Patel

In a typical filter, the number of taps is determined by the cutoff and transition width parameters.  Since those are changable at runtime, the
  resulting filter-length will also change at run-time.

The Parkes-McLelland algorithm is used to compute the filter taps from the given input parameters.  Change those parameters, and the
  resulting filter parameters (and length) will change.