What's going on in PG????

[troymail]

A little of topic…. So what happens to the old system and its frequencies? Can the old system be re used again to some other jurisdiction? ....... With the change of the frequency of the “dispatch channel” does this also mean the “paging frequency” will be changed as well?

For What it's worth: According to this article: Prince George's County Fire/EMS Department: PGFD's New Radio System - "The Sky is Falling - The Sky is Falling"

"The county will retain a few public safety channels such as 155.685 and 155.79. One will simulcast the fire dispatch talkgroup and the other will be a telemetry circuit for firehouse alerting. The majority of the county’s VHF and UHF frequencies will be returned to the FCC for re-licensing."

 

[ka3jjz]

Thanks to a contributor who wishes to remain anonymous, I've made various corrections - I'll edit this when I get to work and fix any typos I made.

Interesting that MSP Forestville will be on the system, but not College Park. Also interesting that there will be some FDMA on the system, partially confirming the rumor heard some time ago

Please don't put people's name in with the descriptions. Remember the wiki captures the IDs of whomever makes changes, and besides we don't want them going into the database (which this list will eventually do).

There are still lots of holes, so keep the research going...best regards..Mike

 

[Dewey]

Thanks much Mike and Anonymous!!!

Looking at the TDMA talkgroups and their FDMA counterparts, the pattern appears to be the same with the only exception being that the TDMA talkgroups are spaced by 6, while their FDMA counterparts are spaced by 2. This is pure speculation, but I have the feeling that the completed FDMA talkgroups would look something like this:

293 - A Sector
295 - B Sector
311 - C Sector
297 - D Sector
299 - E Sector
309 - F Sector
301 - G Sector
303 - H Sector
305 - J Sector
307 - K Sector

I can't say enough that it is speculation, but it is based on the spacing and pattern of the known TDMA/FDMA channels. Who knows, maybe the in-betweens (294, 296, 312, etc) are the tac channels.

Dewey

 

[baybum]

Personal TG Verification

With reference to TG 223.
Mt.Ranier and Bladensburg shared the same conventional frequency of 453.900.
When I was capturing TG's last week, I copied a call at a Mt.Ranier address. (I grew up in that area).
I have not heard anybody from Bladensburg on that TG. But that's not to say that they are still not sharing it, I just didn't hear them.
Mt Ranier needs to stay in the tag and Bladensburg should be added when it is verified as still paired with Mt. Ranier, or on a TG of their own.

Thanks.

 

[gesucks]

With reference to TG 223.
Mt.Ranier and Bladensburg shared the same conventional frequency of 453.900.
When I was capturing TG's last week, I copied a call at a Mt.Ranier address. (I grew up in that area).
I have not heard anybody from Bladensburg on that TG. But that's not to say that they are still not sharing it, I just didn't hear them.
Mt Ranier needs to stay in the tag and Bladensburg should be added when it is verified as still paired with Mt. Ranier, or on a TG of their own.

Thanks.

There is nothing to confirm. Mt Ranier does not have their own dispatch. They are dispatched by the Bladensburg Police Department on Bladensburg's UHF frequency and on Bladensburg's Talkgroup.

 

[baybum]

And as stated, I heard them dispatched to a call at a Mt.Ranier address on TG 223.
Mt. Ranier is an independent town and should be listed under TG 223 just as the other towns are listed with their respective TG's.
I guess what we're saying is, include both towns under the same TG. I was simply stating that I personally haven't heard Bladensburg on that TG. I sat on it for about 30 minutes.

 

[troymail]

I can't say enough that it is speculation, but it is based on the spacing and pattern of the known TDMA/FDMA channels. Who knows, maybe the in-betweens (294, 296, 312, etc) are the tac channels.

Dewey

Not sure I follow -- when you say "known TDMA/FDMA channels" what does that mean (particularly with regard to the "FDMA channels")?


BTW - while I am here -- have you seen any concrete indications of activity on any 8Cx talkgroups (Pro96Com or other, etc.)? Specifically, 8C7?

 

[Dewey]

Not sure I follow -- when you say "known TDMA/FDMA channels" what does that mean (particularly with regard to the "FDMA channels")?


BTW - while I am here -- have you seen any concrete indications of activity on any 8Cx talkgroups (Pro96Com or other, etc.)? Specifically, 8C7?

I'm going on the updated information posted in the wiki by Mike. What led me to this "speculation" is how the numerical ordering of the TDMA talkgroups "jump over" A3/Charlie and A6/Frank before coming back to them. When you look at the listed FDMA talkgroups, you see the same "jumps", with the difference being the +2 jumps versus the +6 jumps in the TDMA talkgroups. Clear as mudd????????

Concerning Pro96Com, I still have yet to see any FD activity on the south site outside of the dispatch channel. I must admit that I haven't been looking "hard", but I have been looking.

Dewey

 

[troymail]

I'm going on the updated information posted in the wiki by Mike. What led me to this "speculation" is how the numerical ordering of the TDMA talkgroups "jump over" A3/Charlie and A6/Frank before coming back to them. When you look at the listed FDMA talkgroups, you see the same "jumps", with the difference being the +2 jumps versus the +6 jumps in the TDMA talkgroups. Clear as mudd????????

Sorry - I'm still confused over what you are calling "FDMA talkgroups" - for this system, I believe there are talkgroups that are TDMA (6.25 khz channel --- 1/2 of a full FDMA 12.5 khz channel) almost full time -- but occasionally some of those same talkgroups are switched (automatically I believe) to FDMA (full 12.5 khz channel) when/if a subscriber with only an FDMA radio comes onto the talkgroup - and then back to TDMA once that subscriber leaves the group.

Concerning Pro96Com, I still have yet to see any FD activity on the south site outside of the dispatch channel. I must admit that I haven't been looking "hard", but I have been looking.

This is good (from my perspective) -- if things work like the police, when they do come active, I think I'll be able to hear tem in the North... just haven't heard anything yet -- which I'm not quite sure I understand (why)...

 

[Dewey]

Sorry - I'm still confused over what you are calling "FDMA talkgroups" - for this system, I believe there are talkgroups that are TDMA (6.25 khz channel --- 1/2 of a full FDMA 12.5 khz channel) almost full time -- but occasionally some of those same talkgroups are switched (automatically I believe) to FDMA (full 12.5 khz channel) when/if a subscriber with only an FDMA radio comes onto the talkgroup - and then back to TDMA once that subscriber leaves the group.

...

Take a look at the wiki... talkgroups 295 - 303 are listed as FDMA talkgroups for the various sectors.

Dewey

 

[troymail]

Take a look at the wiki... talkgroups 295 - 303 are listed as FDMA talkgroups for the various sectors.

Dewey

O! Now I see - doh!

I'd love to see the Police template --

If I had to guess, I'd guess these are system "failure" talkgroups - in the event the system didn't do what it was supposed to do (i.e. auto-switch to FDMA when necessary) -- if things fail, all units would be told to switch to the FDMA talkgroups -- but like you said earlier, just (huge) speculation on my part.

In failure mode, they'd probably "give up" the TAC and SAT talkgroups since they would at that point be using effectively twice as many "channels" ... again - speculation on my part.

 

[Dewey]

As posted by Chief34 earlier... I am now seeing (Pro96Com) and hearing the south FD talkgroups (8C7) on the south site. I also heard a dispatch to the north talkgroup of 8A2, but as expected, I did not see or hear that activity.

Dewey

 

[troymail]

As posted by Chief34 earlier... I am now seeing (Pro96Com) and hearing the south FD talkgroups (8C7) on the south site. I also heard a dispatch to the north talkgroup of 8A2, but as expected, I did not see or hear that activity.

Dewey

Interesting - are you hearing 8C7 all of the time when Ch 7 is active or only sometimes? I only hear 8A2 sporadically even though they dispatch there constantly

 

[troymail]

BTW - what is the TGID for 8C7?

 

[Dewey]

BTW - what is the TGID for 8C7?

1061... also I did just see the north talkgroup of 8A2 in Pro96Com pop up on the south site, but it was in TDMA mode.

Dewey

 

[troymail]

1061... also I did just see the north talkgroup of 8A2 in Pro96Com pop up on the south site, but it was in TDMA mode.

Dewey

Reception at my location is pretty bad but I'm going to park my radio on 1061 all night and see if I catch any fish.....

 

[Dewey]

Interesting - are you hearing 8C7 all of the time when Ch 7 is active or only sometimes? I only hear 8A2 sporadically even though they dispatch there constantly

So far, yes... but it takes a little work to coordinate all of this. I have to run three scanners, 1 feeds the control channel to Pro96Com, 1 is monitoring the trunked system, and 1 is scanning the conventional frequencies. As soon as I made my post about seeing and hearing channel 7/8C7, it went TDMA

Dewey

Edit: I can now update this and say no to "all of the time". I'm hearing transmissions on conventional channel 7 that are NOT showing up in Pro96Com. BTW, a LOT of equipment has just been dispatched to channel 10/8A11.

 

[Dewey]

Well, you can chalk one up to technology advancing too fast. J Sector is working a major crime, which conventional channel 3 happens to be carrying at the moment. MSP Trooper 2 keeps trying to call the dispatcher, but he's (Trooper 2) is invisible to her... he's conventional, and she's on the trunk. To make matters worse, she (the dispatcher) calls him every so often, but he's not hearing her either due to the difference. So far, they have called each other about 5 or 6 times, but neither is hearing the other!

Dewey

 

[baybum]

That's interop for ya...PG buys a system that nobody around them has.

 

[troymail]

Well, you can chalk one up to technology advancing too fast. J Sector is working a major crime, which conventional channel 3 happens to be carrying at the moment. MSP Trooper 2 keeps trying to call the dispatcher, but he's (Trooper 2) is invisible to her... he's conventional, and she's on the trunk. To make matters worse, she (the dispatcher) calls him every so often, but he's not hearing her either due to the difference. So far, they have called each other about 5 or 6 times, but neither is hearing the other!

Dewey

That's a patch issue -- Anne Arundel struggle with patches with helicopters for years and years -- now the helicopters are on the trunk system. I suspect the MSP helicopters just haven't been programmed for the new PG system yet.