Patched Channels

Spitfire
Posts: 12
Joined: Thu Oct 04, 2012 4:13 pm

Patched Channels

Post by Spitfire » Mon Jan 28, 2013 8:45 pm

Besides the forums being a bit underused and the bots spamming, I noticed that the receiver doesn't seem to like to follow patched talkgroups. I tried to follow an incident on DPD District 5 today (1/28/2013), and at 20:28, you can hear the dispatcher announcing that they were patching to Blue NW. The result of the patch was that District 5 fell silent.

f0urtyfive
Site Admin
Posts: 35
Joined: Sun Jul 08, 2012 1:50 am

Re: Patched Channels

Post by f0urtyfive » Tue Jan 29, 2013 9:05 am

You are very right. Unfortunately when a "patch" is created what really happens is there is a patch announcement that happens including all the patched TG's and a new talkgroup is used (in the 1700 range I believe). So the patched calls are captured (on an alternate TGID), but since there's no recording built in to the app of when the patch announcements are and what TGs are included theres no data to converge those patched calls into the correct TGs.

Let me see if I can jerry rig something to just keep track of patches and copy calls into all the patched talkgroups when they happen.

f0urtyfive
Site Admin
Posts: 35
Joined: Sun Jul 08, 2012 1:50 am

Re: Patched Channels

Post by f0urtyfive » Sun Feb 03, 2013 9:34 pm

FYI, I've implemented a new CAPTCHA on the forums to try to catch more spammers (seems to be working so far). I'm also about to push a new code revision to the receiver that will capture the necessary info on Patch creation / destruction and will apply a change to the website to interpret that data appropriately (so the system should auto-follow patches now).

Thanks,
Matt.

Spitfire
Posts: 12
Joined: Thu Oct 04, 2012 4:13 pm

Re: Patched Channels

Post by Spitfire » Tue Feb 05, 2013 9:09 pm

Thanks for the quick response! Just a quick question off topic, are there any plans to add additional channels or does your receiver have an upper limit of channels it can simultaneously receive?

f0urtyfive
Site Admin
Posts: 35
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Re: Patched Channels

Post by f0urtyfive » Wed Feb 06, 2013 10:14 am

The receiver captures the entire trunked system all the time. The channel limitation is an artificial limit to avoid legal issues. I added some additional fire channels the other day, if you have any requests I can take a look at them.

Spitfire
Posts: 12
Joined: Thu Oct 04, 2012 4:13 pm

Re: Patched Channels

Post by Spitfire » Thu Feb 07, 2013 10:32 am

I was just wondering about some of the Network First talkgroups (Red/Blue/Green/etc) and maybe Metro Net? The only tower on DTRS I can currently receive rarely carries any of those talkgroups when Denver is working an incident with surrounding metro agencies.

I also have a few more questions that are unrelated and apologize for taking this topic off course. So the basic concept of this system is that your receiver basically receives and records everything, but then software goes about decoding which recording goes to which talkgroups you want monitored and then trashes (or stores?) the rest? Also, if you had a receiver (or software) that could decode APCO-25, would this same concept work on DTRS?

Thanks for the prompt responses!
Last edited by Spitfire on Fri Feb 08, 2013 4:44 pm, edited 1 time in total.

f0urtyfive
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Re: Patched Channels

Post by f0urtyfive » Thu Feb 07, 2013 8:19 pm

I've added Red NE/NW/SE/SW and FERN to the allowed groups, as well as GREEN 1/2 for now. The same is possible on DTRS yes, just takes more receiver code.

Spitfire
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Joined: Thu Oct 04, 2012 4:13 pm

Re: Patched Channels

Post by Spitfire » Fri Aug 28, 2015 10:12 pm

Bumping this thread after 2.5 years, but there seems to be a separate issue with patched talkgroups. Occasionally when talkgroups are patched, they produce duplicate audio files of the same transmissions. An example can be seen, once again, on District 5 for 08/28/2015 after 21:26. I think Blue SE was patched into District 5, but I'm not 100% certain of that.

f0urtyfive
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Re: Patched Channels

Post by f0urtyfive » Sat Aug 29, 2015 4:30 pm

Interesting, it definitely does look like that is happening, all the metadata is left in the MP3 files, so if you download two calls you can kind of get an idea of what is going on,
This is the comment field on both files:

Code: Select all

3,2015-08-29 03|28|02.961310,[1704, 593]
So they're both recorded off the same frequency (first field), at the same time (second field) and they both have 1704 and 593 TGs patched (Blue SE and District 5). Both also are originating from one of the patch TGIDs (1547). So, I think what is happening is there are two record threads spinning up and capturing the call, but I'm not really sure why. It could be that Blue SE is now a talkgroup that can be directly associated to, so it announces the "patch" twice, once for 1704, once for 593, and thus gets a copy of the call for each tg, then because both show patched to the opposite both calls show up in both places... But I'll have to look more in-depth at protocol to figure that one out.

jbeen
Posts: 11
Joined: Fri Jul 03, 2015 2:54 am

Re: Patched Channels

Post by jbeen » Sat Oct 24, 2015 6:16 am

As another data point on this, DPD D4 & Blue SW were patched on 2015-10-23 from about 23:13-23:43.
Air-1 was tracking a car, which eventually crashed at Hampden & S. Inca.
About 20 units were on scene, from Denver, Sheridan & Englewood.

The transmissions were duplicated on District 4, which is better than not hearing them at all. :-)

Here are two clips:
http://radiocapture.com/audio/2015/10/2 ... 315105.mp3
http://radiocapture.com/audio/2015/10/2 ... 315117.mp3

Here's the comment data (same on both):
13,2015-10-24 05|20|52.280816,[577, 1706, 579, 529]

The group ID was 1548.

Just wanted to provide another example.

Regards,
Josh

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