p25 Phase 1 audio issue?

[Jim Kovalsky]

I commented on an earlier thread that I had some "lost" audio using Alpha 6. It's a new install, so I haven't used previous versions.

The system I'm monitoring is a mix of P25 Phase 1 and 2.  The Phase 2 audio is all great.  The phase 1 audio is good about 75% of the time.  If I listen on my Uniden scanner, all of the audio is fine.

Is there something I could be missing in my config to cause this?  I've attached a sample of what some of the P1 audio sounds like.  Sometimes it just cuts short, other times there are "garble" noises...  

At the same time, I'm finding this to be an AMAZING piece of software!

[Brian pfister]

By chance is the Phase 1 system a simulcast system, involving more than 1 site? Your audio sounds much like mine does sometimes thru SDRtrunk. I'm fortunate to be fairly close to the main site, so most of my signal is coming from that one site (tower), but occasionally I get the same garbled audio on both my SDS200 & SDRtrunk. Even the $5,000 Motorola portables the FD's all use around here sometimes get the same garbled audio. However, can't complain, the SDRtrunk software is free, and works just as well as a $700 Uniden scanner.

[wemana...@gmail.com]

On Saturday, January 9, 2021 at 10:36:44 PM UTC-5 jkova...@gmail.com wrote:

I commented on an earlier thread that I had some "lost" audio using Alpha 6. It's a new install, so I haven't used previous versions.

The system I'm monitoring is a mix of P25 Phase 1 and 2.  The Phase 2 audio is all great.  The phase 1 audio is good about 75% of the time.  If I listen on my Uniden scanner, all of the audio is fine.

This only occurs for PI audio? PII audio is always fine?

JMBE lib? Did you self compile or compile via the built in system? Version?

Is it the SAME TG or DIFFERING TG? ie: It occurs only for the (stupid!) Locution Dispatch group? Or any PI group?

Same FREQUENCY this occurs on? Or on MULTIPLE FREQUENCIES but the SAME TG?

Are SDR(s) and scanner connected to same antenna system? Antenna setups? Type of scanner make/model?

Hunch, and only that, but if its only on PI audio then its not likely the case. So more details on when this occurs as to whats going on.

Enable traffic channel logging and decoded logging.. only do it for a while! Capture some of these events and disable again! It  will CREATE TONS OF FILES quite quickly! Large amounts of data here. Possibly some of these will have clues on issues.

Palm Beach County is a SIMULCAST system so you should select LSM for the Tuner setup.

[wate...@gmail.com]

I'm not OP, but I've been running into this problem also, seems like it started on Alpha 5 or 6 (I definitely don't remember this happening in earlier builds). Things will be coming in clear and then all of a sudden I either won't hear a reply or a dispatcher will go to talk and it's just silence for the entire call. I don't have any PII systems around me so my experience has just been with a PI system. I have noticed (just saw it happening this morning) one thing when this happens, if I have SDRTrunk open and I'm watching the traffic, on a missed transmission it will show up as pink/encrypted for just a split second when the transmission starts and then it changes over to a normal blue call. I'm guessing SDRTrunk is detecting it as encrypted and not playing the audio? I run SDRTrunk and UniTrunker at the same time and know for a fact the transmission is not encrypted as I can see it as regular traffic in UniTrunker and I can hear it if I enable a Voice VFO (normally keep them disabled).

The system I'm monitoring is a Simulcast and I'm using LSM in the Tuner setup. I'm using two NooElec Smartee's with the antennas they come with. The antenna doesn't seem to make any difference as I still receive traffic fine (except for these pesky missed calls every once in a while) even with no antenna attached, I just keep one attached. SDRTrunk Alpha 6 on Windows 10. Happens on multiple frequencies on multiple talk groups, though sometimes one frequency is much worse than the others. JMBE was compiled with the built in system.

[wemana...@gmail.com]

On Tuesday, January 12, 2021 at 2:51:31 PM UTC-5 wate...@gmail.com wrote:

I'm not OP, but I've been running into this problem also, seems like it started on Alpha 5 or 6 (I definitely don't remember this happening in earlier builds). Things will be coming in clear and then all of a sudden I either won't hear a reply or a dispatcher will go to talk and it's just silence for the entire call. I don't have any PII systems around me so my experience has just been with a PI system. I have noticed (just saw it happening this morning) one thing when this happens, if I have SDRTrunk open and I'm watching the traffic, on a missed transmission it will show up as pink/encrypted for just a split second when the transmission starts and then it changes over to a normal blue call. I'm guessing SDRTrunk is detecting it as encrypted and not playing the audio?

Is this LOCAL AUDIO ie: audio out of speakers on the PC?

OR

IceCast audio, ie: audio via VLC from your IceCast server

OR

a Recording?

If you can setup either or both recording of a TG where you notice this and IceCast feed to your IceCast server to test? Do you get missing tx's from this audio?

I very rarely listen to local audio, and I am not noticing that on IceCast audio. I don't record much except some stuff to find some users in a certain situation.

SDRT will look at the bits in the data stream to determine if this is encrypted or clear. The way this is sent in some situations can be delayed, thus in some instances a few blips of encrypted audio may sneak out. There was a code update to adjust for this.

Two issues present themselves... Bad code checks for this indicator or RF issues causing bad bits in the stream which cause errant encrypted indication and the audio is cut off. The 2nd would be related to RX site paramters, user parameters.

Could be combo of both.

 

I run SDRTrunk and [redacted|ed] at the same time and know for a fact the transmission is not encrypted as I can see it as regular traffic in [redacted|ed] and I can hear it if I enable a Voice VFO (normally keep them disabled).

Lets try what I listed above and see if its missing in other areas... Not saying I am not having this, just I"ve not noticed it, and that may be the way I "listen."

Local audio is pointless for me as PC's are stuff in my lab which is not in the room which I use other PC's to work...

The system I'm monitoring is a Simulcast and I'm using LSM in the Tuner setup. I'm using two NooElec Smartee's with the antennas they come with. The antenna doesn't seem to make any difference as I still receive traffic fine (except for these pesky missed calls every once in a while) even with no antenna attached, I just keep one attached. SDRTrunk Alpha 6 on Windows 10. Happens on multiple frequencies on multiple talk groups, though sometimes one frequency is much worse than the others. JMBE was compiled with the built in system.

So its just MISSING audio,

and NOT

Garbled audio.

The original post had garbled audio which is likely from some known discernible areas, depending on data.

You too could enable traffic and decoded message logging options for awhile and then math up the log data to the missing grants. To review.

It may take *.bits recordings if this other issues at play.