Strange GRE Radio Behavior on SAFE-T
Preface: This started today. I have noticed it on both my PRO-2096 and my PSR-500. Both are using the correct rebanded trunking tables and have all of the latest available firmware updates loaded. Neither radio has ever done this before. Ever.
There seems to be something strange happening with the outbound control channel instructions and/or voice channels, at least on the Greenwood site. I say that because I have noticed the same thing happening on two separate radios. Both are GRE-built radios, but are different models. At least four times today, I've noticed that both my PRO-2096 and my PSR-500. The radio will hang on a voice channel for an indefinite period of time, looking as through it received a channel grant, but never went back to the control channel. As I type this, its happening. It is sitting on 41GPD-DSP, voice channel 854.4875, full RSSI, decoding no audio, and what's really perplexing is that UniTrunker is showing no channel grants on the site. No active voice channels. That's right. Yet, if another talkgroup comes up on the site while it's hanging like this, and happens to land on the same voice channel, it will pass audio for the other talkgroup while displaying the previous talkgroup that it was hanging on. Its almost like the voice channel never dropped from the previous talkgroup, yet the outbound control channel instructions don't indicate such.
I'm sure that in P25 digital voice (the voice channels, not the control channel), there is an embedded OSW that indicates end of transmission and/or the present talkgroup being monitored, as well as other channel grants on the site (this is what makes priority scan work on subscriber radios) and I don't believe the GRE scanners decode these commands, just the digital voice. That's why when another talkgroup pops up on a voice channel that just had a talkgroup on it that the radio was listening to, we will hear the other talkgroup, even through the radio looks as though its still receiving the previous talkgroup based on what is on the display. What I have noticed today seems to be the same condition on steroids. The voice channel repeater will actually continue to transmit P25 digital voice with no audio, all the while the OSWs on the control channel indicate that the voice channel is not active. The radio will just sit there listening to nothing for an indefinite period of time with full RSSI on the meter. It will even hang on sometimes after another talkgroup comes up on the voice channel and then ends its traffic. Most of the time, it drops like it is supposed to and the radio goes back to the control channel to listen for more OSWs. The times that it doesn't, its very annoying, because there are lots of talkgroups that I don't care to listen to, and I have never noticed this happen since I have been listening to the site since 2005.
This seems to be intermittent, and I haven't yet noticed if any one voice channel is affected more than the others. 854.4875 (LCN 139) seems to be the one I've noticed it the most on. I have yet to listen to any other sites to see if it is happening there. It may be the site messing up, or, who knows, maybe its intentional. It kind of reminds me when GE put the string of beeps on the end of EDACS channel grants so the scanner would just sit there and listen to beeps while the traffic was continuing on another voice channel, and as a result, the scanner listener would miss traffic. For a while, this foiled scanners trying to track a talkgroup as it cycled through the various voice channels. Then the subaudible data started getting decoded by the scanners, and the problem was solved.
Thoughts?
