SDFD Dispatch Talkgroups

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SkipSanders
Posts: 168
Joined: Sun Dec 03, 2006 10:12 pm

SDFD Dispatch Talkgroups

Postby SkipSanders » Mon Dec 03, 2007 1:04 am

Seems that SDFD is now (actually, for some time now) running three talkgroups all multicast as 'dispatch', but there are some 'tricks' to it.

Groups in the 'dispatch' multicast are:

4688 'Fire Dispatch Simulcast' - This is, now, the 'master' group.
5008 'Fire Dispatch'
5168 'Fire Admin'

If you program in only 5008, you will miss a LOT of dispatches, now.

The actual talkgroup the system is on is 4688 now, for 'normal' dispatches, so a scanner does not 'get' the dispatch if it's on 5008.

It seems that 5008 IS used, when dispatch wishes to call a battalion chief in the field... but not other units, and an occasional dispatch seems to come out on 5168, but not the other two, also.

So, scanners should have both 4688 and 5008, and probably 5168 as well, to get all dispatch traffic.

Hmm, should mention as well, if you have an older scanner like the 895 that uses ONLY status bit modified group numbers, add 7 to the group number to get the 'multicast status' group number, or 4695, 5015, and 5175.

jkphotog1
Posts: 69
Joined: Tue Oct 26, 2004 2:11 am

Postby jkphotog1 » Mon Dec 03, 2007 3:45 am

Good info. I have also heard 7A on 5139 and 5011. It seems some software will not let you enter the oddball talkgroups since they are nots divisible by 16. There are some radios that won't let you enter these oddball talk groups. I will use often use a Uniden 235 with all the possible combinations plugged to not miss a 7A dispatch. Then scan all the combinations.

http://www.wa8pyr.net/800mhztutorial.htm#type2

Finally, if you come across a talkgroup that doesn't quite match the "start at 16, add 32" or "start at 16, add 16" progressions, you may have found a talkgroup using a special function. The added numbers that define these are:

ID+0 = Normal talkgroup.
ID+1 = All Talk Group (a Type II "fleetwide" or "all call" function).
ID+2 = Emergency talkgroup (somebody hit the emergency button).
ID+3 = Bi-directional talkgroup crosspatch.
ID+4 = Emergency patch.
ID+5 = Emergency multi-select.
ID+6 = ? (may not be used).
ID+7 = Multi-select (dispatcher broadcast on more than one talkgroup).
ID+8 = DES/DVP (digital encryption) talkgroup.
ID+9 = DES/DVP All Talk Group.
ID+10 = DES/DVP emergency talkgroup.
ID+11 = DES/DVP bi-directional talkgroup crosspatch.
ID+12 = DES/DVP emergency patch.
ID+13 = DES/DVP emergency multi-select.
ID+14 = ? (may not be used).
ID+15 = DES/DVP multi-select.

hodad200
Posts: 146
Joined: Wed May 10, 2006 11:59 am

Postby hodad200 » Mon Dec 03, 2007 4:03 pm

ugh this again? maybe tim can shed some inside light...

SkipSanders
Posts: 168
Joined: Sun Dec 03, 2006 10:12 pm

Postby SkipSanders » Wed Dec 12, 2007 11:19 pm

As of today (haven't had trunker running for a while), patching has shifted, and now TG 5008 is the 'master' talk group, with 4688 and 5168 secondary, with 'actual' dispatches going out (mainly) on 5008 again.

I'd keep all three in, as it can change around at any time.

N6766J
Posts: 48
Joined: Mon Feb 19, 2007 2:32 pm

Re: SDFD Dispatch Talkgroups

Postby N6766J » Mon Dec 17, 2007 3:53 am

SkipSanders wrote:Seems that SDFD is now (actually, for some time now) running three talkgroups all multicast as 'dispatch', but there are some 'tricks' to it.

Groups in the 'dispatch' multicast are:

4688 'Fire Dispatch Simulcast' - This is, now, the 'master' group.
5008 'Fire Dispatch'
5168 'Fire Admin'

If you program in only 5008, you will miss a LOT of dispatches, now.

The actual talkgroup the system is on is 4688 now, for 'normal' dispatches, so a scanner does not 'get' the dispatch if it's on 5008.

It seems that 5008 IS used, when dispatch wishes to call a battalion chief in the field... but not other units, and an occasional dispatch seems to come out on 5168, but not the other two, also.


Hmm, should mention as well, if you have an older scanner like the 895 that uses ONLY status bit modified group numbers, add 7 to the group number to get the 'multicast status' group number, or 4695, 5015, and 5175.


We broadcast dispatches on Admin (5008) and Dispatch (5168). The calls also go out on the Station Alerting circuit (microwave with landline backup) Someone told me that 4688 is a Lifeguard TG that simulcasts FD dispatch.
We don't see the TG ID's, just the TG name and the Fleet map positions on the radio consoles. (7A and 7B)

SkipSanders
Posts: 168
Joined: Sun Dec 03, 2006 10:12 pm

Postby SkipSanders » Mon Dec 17, 2007 5:45 am

We broadcast dispatches on Admin (5008) and Dispatch (5168). The calls also go out on the Station Alerting circuit (microwave with landline backup) Someone told me that 4688 is a Lifeguard TG that simulcasts FD dispatch.


While that may be the 'theory', day to day monitoring of the actual trunk system via Unitrunker shows that commonly, 4688 is the actual transmit talkgroup, with radios on 5008 and 5168 receiving it as a multi-select. Few if any scanners understand patching or multi-select, and thus, a scanner will only receive the transmission if it's got 4688 programmed in as a talk group.

Other days, it may be 5008 that's 'primary' and the actual on-air talkgroup. As a result, a scanner listener who wants to receive all the dispatches must have all three groups entered into the scanner.

This is all an artifact of how Motorola handles 'Multi-select'. You may have set 5008 (7A) on the console, but the controller will actually SEND the transmission (officially) on group 4688 when that group is the primary of the multi-select, expecting all radios in the field to 'know' that any radio set to 5008 or 5168 (or 4688) should receive anything coming in on 4688.

OSW
Posts: 33
Joined: Sat Oct 01, 2005 3:06 am

Postby OSW » Thu Dec 20, 2007 10:24 pm

SkipSanders wrote:Other days, it may be 5008 that's 'primary' and the actual on-air talkgroup. As a result, a scanner listener who wants to receive all the dispatches must have all three groups entered into the scanner.

Which TG that the MSEL goes out over is called the SuperGroup and can change depending on the console used. It generally happens when a different console is used because the pre-loaded list for the MSEL has a different order. The system doesn't pick the TG ID so in reality it can eventually change.


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