Why does my audio quality vary so much?

[Jim Kovalsky]

First, thanks for all of the effort into SDRTrunk -- it's an amazing piece of software.  

I have multiple servers running in multiple areas for different P25 systems, and I've not run into this issue previously.  On my two latest installs the audio quality can vary widely from call to call.  These two examples are successive recordings from the same talkgroup less than a minute apart.

One is nice and clear, and the other is underwater.  

I'm running a 24gig Ryzen 7 Win 11 pro box with no other tasks.  My CPU usage is under 10%.  Running 0.6.1 Final...

I've tuned my ppm as close to zero as I can get it.  I'm close to the towers..

I'd love to hear any suggestions.

[Eric F.]

That sure sounds like a signal quality problem. With digital signals quality is everything, signal to noise ratio, bit error rate. Signal strength is mostly irrelevant. Strength need only be good enough to be decoded without error. Interference, noise (in the air radio noise or local), multi-path distortion, and a number of other things can cause problems. Too much signal is as bad as too little. Too much signal when monitoring a simulcast system can be problematic. Typically I/Q demodulation deals with that pretty well. But, enough signal to saturate the receiver is bad. The RTL and similar dongles being only 8 bit are quite easy to overload. It's not uncommon for one frequency in a trunk system to be problematic while others are fine.

"Win 11 pro box with no other tasks" is a contradiction in terms.

[Zach Rutledge]

Is it possible that some of the frequencies used by the systems you monitor are right on the edge of the band your SDRs are monitoring?  I monitor a few systems and one has some frequencies that are just on the edge of my radio's bandwidth, and there's a pretty noticeable rolloff in signal strength on the edge like that.  I get choppy audio like that when one of those channels are in use.

On Saturday, February 14, 2026 at 1:23:23 PM UTC-6 jkova...@gmail.com wrote:

[Eric F.]

And there is that. The edges of the available spectrum with many of these tuners can be filled with images.