TRX-2 DMR Audio is Warbly and Watery

[m42duster]

Our local PD and Fire went DMR a few months back. They are not using any encryption or privacy modes. The departments are in Lancaster, Ohio.

Anyways, most of the time, the receive audio sounds highly processed and garbled and watery sounding. Can't understand them at times. This is mostly noted with dispatch. Sometimes, the mobile units are understandable. I'm not to familiar with digital, but it sort of sounds like to much DSP, like on my ham rigs. What settings can I try to tweak? I'm about to skip these two departments. I'll try to figure out how to do a recording if that will help diagnose.

 

[djeplett]

IIRC the DSP settings only affect P25 reception. But you could try changing them anyway to see if they make a difference. They are called "DSPLevelAdapt", DAC Gain and ADC Gain.

You may also be dealing with some signal distortion due to multipath. Try turning the attenuator on or moving the antenna around a bit.

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[m42duster]

I'm leaning toward multipath. Cleared up with higher gain antenna. Thanks, I should have caught that.

 

[johnnyelectron]

Even using a DMR radio, like the MD-380, it is still cruddy, and the audio varies by a factor of 6dB between mobiles and dispatch, so it isn't just a Whistler issue.

 

[Ubbe]

IIRC the DSP settings only affect P25 reception.

Yes, it's only for P25 and not for DMR or NXDN.

/Ubbe

 

[DJ11DLN]

Even on commercial gear, DMR isn't as clear as P25.

 

[nanZor]

Part of the reason may be the agency using older dmr radios, which had issues with AGC. Everybody seemed like they were shouting.

The solution for many was to turn off AGC and change the mic-gain to something reasonable. Either that, or upgrade to the latest firmware / radio upgrade:

DMR-MARC Network

I know of a few amateurs that helped out their own workplace by convincing the powers that be to have the radios reprogrammed this way, or upgraded to the latest firmware where AGC has been controlled in a more refined manner.