In Reply to: Talk Group Question! posted by Chris on December 27, 2000 at 14:36:18:
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.
Bottom line is that rather than an integrated system serving all of King County there are three independent systems which are connected together. More expensive and less efficient, but since it's public money efficiency and economy aren't always the most important considerations.
: This may seem like a rookie question, but it is one that I would like answered
: Why is it when I'm on the Seattle Sub-System I can hear all of the SFD Talk Groups. But only
: some of the other Talk Groups from the other Sub-Systems. For example: I can listen to all of
: SFD's talk groups, but can only hear VC Fire-1(when I am just listening to fire talk groups). I also can't hear any of the SC Talk Groups like
: Fire-5,6,7,8, and Fire-9. If I hear a alarm dispatched on Fire-1, and the response is on Fire-2,3,or 4
: I have to switch to the KC/VC Sub-System. So whats the deal? I live in an area that gets great coverage for all of the
: simulcast sub-systems. County Guys?