[arm-allstar] notch filter

[Rick Dykstra]

Are you talking about the audio coming over Allstar when you connect to 
the repeater node? Is this someone else's repeater?  If so, it would be 
better to talk to the owner and remove it at the site, or everyone else 
will have the same problem you do.

Rick KR8T

On 3/28/2022 11:41 AM, "Patrick Perdue via ARM-allstar" wrote:
> I have access to a repeater's Allstar node. This repeater has a 162.2 
> hz PL tone, and it's rather loud, especially the third harmonic, not 
> so much the fundamental frequency. Aside from cleaning things up at 
> the source, which is the best solution, I've tried all sorts of things 
> to minimize that tone. That frequency is high enough that even using 
> the rather sharp PL filter, it still leaks through. I've tried various 
> stacks of rxnotch with different bandwidth, located at the center 
> frequency, and also half an octave to either side. This gets rid of 
> that harmonic, but it rings out where the notch center frequency 
> lives. I can adjust how much it resonates by changing the width or 
> adding more filters. Ultimately, I'd love to use something else to 
> process the audio, like a parametric EQ rather than a hard notch. A 
> long time ago, I read about a future iopipe driver for HamVoIP that 
> might allow for such things to be used. Just wondering what the 
> progress on that is.
>
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