[Asterisk-Dev] notch / high pass filter addition to zaptel

[Steve Kann]

Kelly McDonald wrote:

>hello,
>
>I've got a cheapo x100p substitute, (sorry for being cheap), 
>
>everything is working fine with it, had some echo but aggressive echo
>correction fixed this.
>
>The only issue I have left is a ~60hz hum that seems to be coming from
>the card itself (bad ps bypassing is my guess)
>
>I was wondering about adding a high pass filter or notch filter
>somewhere in zaptel, I see that there is already a notch filter set up
>and being used in  ztcfg-dude.c 
>
>
>I'm just wondering if there are any pointers anyone would have for me in
>my attempt to do this, or perhaps this has already been done, and I
>should just 'flip a switch' somewhere. 
>
>Thanks for any suggestions.
>
>Kelly
>  
>

I'd try adding an electrical filter to the line before it goes into the 
card, first.  It may be that the hum is on your line..

-SteveK