Audio filtering options

[John Peterson]

Hello Everyone,

I am really enjoying working with SDRTrunk! Thanks, Denny, for the wonderful piece of software!

I have a quick question: is there any setting where I could perform some audio filtering? Right now, I am using SDRT to monitor/feed audio for analog railroad communications. One of the railroads using an obnoxious 250.3 Hz PL tone. This is audible in the feed, and some listeners complain about the "humming" on this channel. I just need a 250 Hz notch filter.

I know I could send SDRT output to something like VAC. then through a VST plugin or similar, but that defeats the built-in support for Broadcastify.

Thank you in advance for any suggestions!

--
John D. Peterson/w4jdp
http://www.alabamarailfan.com

[old7...@gmail.com]

John,

Sounds like a great idea to me as well.

Monitoring ham repeaters most with ctcss tones can get a bit much.

I noticed it on several other public service channels in the area as well.

The PS signals tend to run higher frequency tones.

You can really hear them. Ham repeaters tend to use lower tones with only a few higher than 160 or so.

The nightly build with the new squelch made such a difference that monitoring rail traffic became a true option and freed up some of my dedicated radio scanners.

They do seem to have some sort of filter however since any tones are much lower in audio level.

Of course if you turn on a RX ctcss mode the filtering becomes almost complete.

Maybe the best idea would be to wish for ctcss and dcs based squelch options.

Probably a good idea since the rumble when listening to some of the NB FM trunking systems can clearly be heard.

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[Zach Rutledge]

I'd love to have a blanket bandpass filter option that would only pass everything between 300-3000 Hz.  That would eliminate the CT tones as well as the harshness on the high end. 

[Colonel Angus]

In the channel configuration page, there's an option under the Decoder:  NBFM section labelled High-Pass Audio Filter.  Turning that on should eliminate PL tones.

[John D. Peterson]

Thanks for the information. I actually already have that turned on for all channels, but the 250.3 Hz tone is still getting through. I couldn't find any documentation on this setting, so I'm not sure what the cut-off frequency is.

--

John D. Peterson/w4jdp
http://www.alabamarailfan.com

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