[Scan-DC] Programming two trunking systems

[Andy]

Doug,

Yes and no.  Here's the science...When a talkgroup for another jurisdiction 
is programmed into the county's Motorola radio's, its programmed in as a 
talkgroup on that radio, but in actuality its mapped to the corresponding 
jurisdiction's radio system talkgroup.  The radio when tuned to this 
talkgroup actually affiliates on the other county's TRS and then 
communicates directly to them as if it were part of the other county's 
system.

For example, a simple imaginary scenario,  Montgomery County Fire Portable 
has 5 talkgoups programmed into it.  The first 3 TG's are MoCo Fire 
Dispatch-7A, MoCo Fireground1-7B, MoCo Fireground2-7C.  The 4th is Howard 
County Dispatch Fire1-A1.  The 5th is Fairfax County Fire Dispatch-4A.  OK 
simple enough.  Now, the when the user of that radio wants to communicate 
with the dispatcher of MoCo Fire on any one of the 3 TG's listed above, his 
radio affiliates itself with the Montgomery County ASTRO TRS when powered 
on.  It received the control channel and more or less it logs on and tells 
the controller, hey I'm here, here's my radio ID.  Great.  Ok, but now the 
user gets dispatched into Howard County for a Barn Fire.  He is instructed 
to respond on talkgroup 15A, which is HoCo's A1.  This is programmed into 
HIS radio as 15A.  What actually occurs is when he switches over to 
talkgroup 15A, his radio actually affiliates (logs on) with the Howard 
County ASTRO TRS and then he's communicating with them on their TG A1.  Same 
thing would apply if after his HoCo call, he gets dispatched into Fairfax 
County and is told to respond on say 16A, which is really FFX Fire 
Dispatch's 4A.  The radio would affiliate with FFX Co's ASTRO TRS.  As long 
as the systems are compatible, then the radio can affiliate on any nearby 
system depending on how they were programmed.   Also, in actuality if you 
look at the talkgroup matrix of Montgomery County's radios on 
RadioReference.com, you'll notice that there are several talkgroups, 
especially in the EMS to Hospital Zone that are actually Tg's on DC's radio 
system, FFX's radio system and I believe one from HoCo's radio system.

I've heard on occasion certain MoCo units dispatched into HoCo for a mutual 
aid resonse and they have to wait until they are near the county line before 
the radio will affiliate with HoCo's TRS.  That's usually for units deep 
inside MoCo, like Tanker 17 had to go into HoCo for a 2 alarmer or something 
once and he couldn't affiliate until he was closer to HoCo with his 
portable.

Hope that clears things up.

Regards,

Andy

----- Original Message ----- 
From: "Doug K." <oldsdoug at hotmail.com>
To: <scan-dc at mailman.qth.net>
Sent: Saturday, January 01, 2005 8:38 PM
Subject: [Scan-DC] Programming two trunking systems


> All,
>
> I'd like to toss out something for discussion... last night was reading on 
> the ARC 250 software yahoo group, and I think it was there that I saw an 
> old thread about trying to program two trunking systems into the same bank 
> on a Uniden trunking scanner.  The consensus was that it can't be done (at 
> least so that the scanner will scan both)... at least I think that's what 
> I saw and understood!  (I'm still green at this trunking business!)
>
> However, comma... I submit to you the following situation - apparently, 
> the radios in Montgomery County fire apparatus can be used to talk to 
> other jurisdictions - so, what if one programs those frequencies and talk 
> groups into the Montgomery County bank of the scanner?  I would guess that 
> this should work if the other jurisdiction is also an APCO-25 800 MHz 
> system.  Seems as if then, they should be received from the Montgomery 
> County point of view, if ya know what I mean... ie, if a Montgomery engine 
> runs into Frederick or Howard County and is assigned a channel like 
> 15-Echo or 15-Delta (I think those are ones I have heard them use for one 
> or the other of those locations), the radio should pick it right up, 
> right?
>
> Am I making any sense?  Does anybody understand this?  Or have I missed a 
> basic premise somewhere (very possible!)...
>
> Thanks-
>
> Doug
>
>
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