In Reply to: Re: Talk Group Question! posted by M on December 28, 19100 at 10:29:47:
: There are three trunked systems: King County / Valley Comm; Seattle; and EPSCA. Each system uses a discrete set of voice and control channels.
: Mobile / portable radios are configured to affiliate with (prefer) the system they are a member of. If the prefered system can't be accessed by the mobile / portable the radio will affiliate with one of the other two systems.
: The reason that the initial dispatch is heard on multiple systems (as best I can tell -- not formally confirmed) is that during the dispatch the Talkgroup is accessed on all three systems so no matter which system your receiver is listening to, you will hear the call.
: When the units respond to the call on e.g. ValleyComm Fire 2, or EPSCA TAC 1, unless there is a portable / mobile affiliated with one of the non-preferred systems you will only hear the Talkgroup on the prferred system.
Pretty close description of how the system works. The reason that Fire-1 may appear on EPSCA or Seattle is that we request it to be there. This is done so that users who may be on FIRE-2 on the EPSCA system, may have their scan function properly. Imagine if your the B/C or HMFIC of an incident. Your radio is aff'ed with EPSCA. You are working a large fire on FIRE-2. ValleyCom then taps out the rest of your small department for a big MVA. Wouldn't it be nice to know where the rest of your troops are ? We do the same thing on several of the small pass sites for KCSO also. You will find KCSO on Snoq Pass all of the time. We do it for a couple of reasons. It allows the scan to function properly. If the deputies radio is on MARS or LERN, they would miss a call from dispatch. It will also help us excercise the base stations at the site. We also sometimes do it to "dump audio". A console cannot make a call on a talkgroup unless a radio is aff'ed with that talkgroup somewhere. If a console patch is in place between a convetional and a trunked asset, such as MARS or LERN, and a conventional call is made, the console will produce a loud "BONK" to indicate that the call is not valid. So if I request that the talkgroup be aff'ed at all the big sites, the mobiles can here it in their scan mode. It also takes the bonk out of a very tempermental dispatchers ear. We do this with the Transit Police and the patch to the Bus Supervisors for Metro. Hope this helps. Questions ?