BCD996XT

[dtuttle]

I am having a terrible time hearing our County's Harris P-25 radio system. All of the other area P-25 systems, such as the Motorola State of IL system and EDACS work fine. It will stop on the talk group but will not give clear audio. Thoughts

 

[Bucko]

Is your system a simulcast system? Simulcast systems are known to give a garbled or distorted audio. I have the same problem here sometimes on our counties MARCS IP system.

 

[dtuttle]

Yes it is a Harris P-25 800Mhz Simulcast System

 

[W6KRU]

Try FM modulation instead of NFM. That helped me.

 

[dtuttle]

I can hear the audio now on the talk group when it is in hold mode but it will not stop on that talk group when it is scanning, any suggestions.

 

[Boatanchor]

Try FM modulation instead of NFM. That helped me.

Try holding your tongue in a certain position too

But honestly, selecting FM or NFM on the x96XT series should have no impact on P25 decoding.
There is no real NFM in the x96XT. No narrow filter, no changes to any RF or IF stage processing & no change to the way digital signals are processed. In fact, there is no point to the menu option even being present in a digital defined system/channel, because it does absolutely nothing.

The only thing the NFM/FM option does is to boost the audio on analogue NFM channels/systems by about 3dB, to compensate for the lower deviation.

Really, the best option is to try and isolate one nearby site from other surrounding (interfering) sites. The best way to do that is with a highly directional antenna such as a yagi. It sucks, but none of the current scanner models is designed to receive Linear Simulcast Mode. Maybe one day, if we are really, really lucky.....

 

[W6KRU]

Try holding your tongue in a certain position too

But honestly, selecting FM or NFM on the x96XT series should have no impact on P25 decoding.
There is no real NFM in the x96XT. No narrow filter, no changes to any RF or IF stage processing & no change to the way digital signals are processed. In fact, there is no point to the menu option even being present in a digital defined system/channel, because it does absolutely nothing.

The only thing the NFM/FM option does is to boost the audio on analogue NFM channels/systems by about 3dB, to compensate for the lower deviation.

Really, the best option is to try and isolate one nearby site from other surrounding (interfering) sites. The best way to do that is with a highly directional antenna such as a yagi. It sucks, but none of the current scanner models is designed to receive Linear Simulcast Mode. Maybe one day, if we are really, really lucky.....

You might be right. I've been known to make mistakes before. I'll have to test again. I use the P25 err display to determine best settings. I am in a very strong signal area and my 396s show full scale SS without an antenna. Where is this 3dB applied?

I just set my mod back to NFM and my errs are in the single digits, so decoding is great today. I'll keep an eye on it and once the decoding degrades to normal, I'll check FM. I got the idea to try FM after UPMan's test on my 436 worked so well.
http://forums.radioreference.com/uniden-owner-tech-support/285012-test-p25-decode-improvement.html

 

[Boatanchor]

No problems

You will find that you can even select AM mode on the x96XT and digital will still work the same.

It may be worth trying on the x36HP because in that model, there are two separate IF filters. One for FM and one for NFM. Changing the FM/NFM setting does alter which filter the signal is fed through and could conceivably have an impact on digital decode performance.

 

[ofd8001]

Sounds like it could be a simulcast distortion issue. This typically manifests itself in either no audio or garbled audio.

Many posts have been written about this elsewhere.

Things to try:

1. Set Attenuation On for the system's site. This can be done through the menu or if you use programming software, via computer.

2. Access the "hidden" settings and tinker with the P25 Adjust Mode and P25 Adjust Level values. This you'll have to experiment to find the best fit - no "one size fits all". (FWIW, on my 996XT on our local system, I'm using 13 and 180).

 

[Voyager]

But honestly, selecting FM or NFM on the x96XT series should have no impact on P25 decoding.

Yet it does for so many...

And there are several P25 bandwidths in use today. Some use bandwidth applicable to NFM, and some use bandwidths that require FM (using Uniden's NFM/FM terms). It's selectable within the system and associated radios. I'm not sure some of the techs know this fact, so they pick a mode and set all the radios for that mode.