SmarTrunk or should say SmarTrunk II is a non-centeralized trunking type system. Meaning instead of all the other systems needing to have a "control channel" or a "home channel" to give routing info as to what repeater the talkgroup should use, SmarTrunk format does that all in the radio.
In laymans terms:
-Non SmarTrunk- : Using talkgroup 12345 to call all the workers. You key-up your radio, the radio calls to a control or home channel, the system verifies unit ID and talkgroup access, tells radio to go to repeater X to place call on talkgroup, radio goes to repeater X and uses talkgroup 12345, you get access tone (chirp) and talk, after talking you un-key, repeater goes back for available usage.
- SmarTrunk - : Using talkgroup 12345 to call all the workers. You key-up your radio (before you even key-up the radio has already been scanning ALL the repeaters of the trunked system and keeps track which are open and which are busy), the radio selects an open repeater (which it is always listening for), the controller for that repeater verifies Subscriber ID and talkgroup access for that subscriber ID, repeater opens up and passes the talkgroup info, you get an access tone (chirp) and talk, after talking you un-key, repeater holds open for X amount of time for quicker turn around and eliminates need to access system again, after x amount of time with no reply by other radios on talkgroup repeater closes and is available again.
So to continue SmarTrunk format does all the logic in the radio. It is always in a constant scan and is always looking to see 1.) which repeaters are open in the system, and 2.) when a repeater is active that the talkgroup it is part of is not active.
As for signalling or working: all users have a Subscriber ID which can be up to a max of 5 digits using any cobination of the 16 DTMF char. (aka 0-9,*,#,A-D). In addition talkgroups are handeled as "paging codes" with a max of 4 digits using any combination of the 10 DTMF char. (0-9). Also each subscriber ID is assigned a primary and secondary paging codes. The Primary one is usually an individual code (for private call) and the Secondary one is usually a group code (for fleet or group call). This is set-up and determined by the system designer/programmer.
The first SmarTrunk format was an analog based format and the SmarTrunk II is a digital based format (similar to DPL tones).
With this type of technology and set-up the system acts like a 1.) radio - radio (mobile to mobile), 2.) radio - phone system [PBX or POTS] (like an autopatch), 3.) phone system - radio (like a reverse autopatch), or 4.) radio/system - system/radio [roaming] (like mobile to mobile however you can cross-over or call someone else on another SmarTrunk system that is connected to this one.)
One of the things SmarTunk prides itself on is that the Subscriber ID and Paging Code is encrypted from mobile to repeater back to mobile so therefore you can NOT decode the Subscriber iD or talkgroup thus making it unable to be scanned.
The other thing SmarTrunk prides itself on is the fact that since the radio itself is monitoring the repeaters that if you have interference from another repeater close by in regards to location or frequency it will not cause interference.
Hope this helps and answers some of the questions that keep coming up over and over again.
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"I went to the doctor and all he did was suck my blood. Do not go to Dr. Acula!" - M. Headberg
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SmarTrunk
Linear Mode
