MotoTRBO Question...

[Forts]

My local PD is migrating to MotoTRBO and have added a 2nd frequency. I've noticed of late that roughly every 60 seconds there is a short digital 'braaaap' on this channel. It's obviously not voice comms. Any idea what it would be? GPS location updates or something? I was originally thinking maybe it was text messaging but the every 60 seconds pretty much rules that out.

 

[RKG]

MotoTRBO uses "unsupervised TDM" for multiplexing. As a result, the subscriber equipment is dependent upon a synch signal from the repeater. If a subscriber keys up and can't find this signal, it sends a request to the repeater, when then issues the synch. During an exchange, and for a period of time afterward (which can be set in the repeater programming), the synch is continued, so that an exchange can be resumed after a short pause without the delay for the request/grant of synch. I believe the brrp you're hearing is the synch signal during timeout.

Edit: Motorola publishes a "Guide" to MotoTRBO (I don't recall the precise title), which is available on the web site. This is required (and interesting) reading for anyone venturing in to what is a pretty different world than most of us are used to.

 

[Forts]

Excellent, I will see if I can track that down. Thanks for the info!

Update: I believe it may be the MotoTRBO System Planner that you were referring to. A link to it can be found in the Wiki or with Google. It certainly is some in depth reading.

 

[motomeso]

Motorola offered linking between TRBO sites recently Forts. Chances are Spectrum has sold them another site or sites to fill in the dead zones that were discovered during the first stage of testing.

When they switch back over to digital the repeaters will have a sync pulse similar to a Passport system that the radios will use to get an RSSI reading and register with the strongest site.

The repeaters are fairly cheap and can be linked together (Up to 15) with the Internet so they can start throwing them everywhere that had problems right down to the basement of the court house if they needed. Chances are they won't use the Internet for a Public Safety system but who knows.