Low voice audio on P25 system immediately after loud "alert" tone transmitted

[freqfreaks]

Does anyone else have a problem with low audio on P25 transmissions immediately after a loud tone? For instance, when the local Sheriff's Department transmits any of their alert or polling tones (which come through quite loud), the voice audio that immediately follows is very low for the first 5-8 seconds or so, but then gradually increases back to normal, but it is a problem because unless you quickly increase the volume, you miss the beginning of the call after the tone. I'm using RTL-SDR's with DSDPlus Fastlane, but I experience it on my Unication as well, so it's not just an SDR thing, but I'm hoping maybe someone else has experienced this and found a tweak for DSDPlus to work around it.

 

[dave3825]

Have you posted about this in your states forum? Since your saying your Unication does it also, that may point towards the system.

 

[freqfreaks]

Have you posted about this in your states forum? Since your saying your Unication does it also, that may point towards the system.

I have not, but it's hard to believe it's a system thing, because how would the system impact both my SDR and my Unication, but not also impact real radios on the system (at least that's my logic). I could see where maybe they would build something into the system to try to level the audio to avoid blowing users ears out, but I can't fathom how it would affect two entirely different radio platforms (one cheap hobbyist level, one expensive professional level), without impacting everyone on the system.

With all that being said, even if it is a system thing, I'm really wondering if anyone has ever seen a symptom like this before, and if so, did they ever find a way, particularly in DSDPlus Fastlane to get around it.

Thanks.

 

[dave3825]

I have not, but it's hard to believe it's a system thing, because how would the system impact both my SDR and my Unication, but not also impact real radios on the system

If it's happening in DSDPlus with a 30 dollar dongle, and its happening on a Unication that costs a few hundred bucks, one would lean towards the system. Unless you have a system radio, how do you know it's not happening on those?

 

[maus92]

Sounds like their audio subsystem is not adjusted properly. Also, operator training, i.e. mouth to mic distance, speaking at a normal, consistent level when transmitting, etc.

 

[R8000]

The "system" just passes through 0's and 1's. It doesn't manipulate the audio in any way because it stays in it's orginal digital format until it hits another radio, console or other "end of the line" device. You may be experiencing dispatch console AGC or a dispatchers headset doing something with it's audio. Some dispatch centers use wireless headsets that have their own audio controls on them.
Sounds to me what you are experiencing is on the dispatch center side of things.