SDRTrunk SDRTrunk - Bad Audio On Some Traffic Channels

[NNJIPScan]

I have been running SDR Trunk for several systems for a few years now (plus some NBFM freqs), with excellent coverage and audio.

I recently upgraded my antenna to enhance coverage, but it feels like I made things worse for one of my systems.

Some of the traffic channels seem 100% with clear audio, but then some traffic channels will start crisp then be garbled all of sudden, with the audio coming in and out.

I have been through lots of the old posts and done a lot of experimenting over the last few days.

In some cases, I can see that SDR Trunk has not re-centered the frequency on the tuner.

Anything else that might be worth checking out?

 

[DSheirer]

Check tuner ppm on each tuner.

 

[wgbecks]

Check tuner ppm on each tuner.

It may be your new antenna system is delivering less signal strength than previously. If this is the case, then the possibility
exists whereby some of the traffic channels (frequencies) may be sitting on the edge of the SDR's usable bandwidth in the region
where effective sensitivity begins to roll off, thus lowering S/N and causing bit errors.

Spectrum plots would be most useful to analyze what's taking place along with a listing of the traffic channel frequencies that
are of concern. As usual, check SDR gains and PPM frequency corrections first and above all.

 

[C_615]

How far way is the system that is giving you the problem compared to the other systems? What antenna did you go from and to? What band is the system on? We need more context.

 

[dickie757]

may be your new antenna system is delivering less signal strength than previous

What about the other way? If simulcast and it is getting both/all signals unequally, can it mess things up?

 

[NNJIPScan]

Thanks everyone for the input. Looks like this was a problem with traffic channels on the edge of the dongle spectrum. I have re-configured the frequency ranges to be as centered as possible, utilizing three SDR-RTL v3 dongles.

For reference, this is for monitoring NJICS West Orange from Central Bergen County. I moved from the out of the box dipole antennas to a Larsen All-Band with ground plane.