As we all know, most DPS communications occur on VHF channels, much of it on their own, now P25, channels. DPS units are, of course, assigned to counties. I'm not sure if it's policy or law, be here goes. DPS units assigned to a county or counties MUST be provided with access to that county's radio system. In the old days that simply meant adding the VHF channels to the trooper's radio. If those channels could not be added to the trooper's radio then the county was required to provide a radio programmed to their system for the trooper's use. With the advent of trunked systems counties were required to provide a trunked radio for each trooper assigned to their county. Thankfully most radios permit the programming of multiple systems (of similar type) into a single radio, otherwise, a trooper could conceivably end up with four or five radios.
In Austin troopers have their VHF radio and Austin/Travis TRS radios. Most of the comms are simulcast. DPS Austin dispatcher is simulcast 100% of the time and DPS has several of their own talkgroups. However, you still hear DPS on Travis and Williamson County talkgroups all the time.
I imagine central Texas presents somewhat of a problem. In the Austin area, a trooper will have his regular VHF radio, a trunked radio on the Austin/Travis system, and possibly an LCRA radio; in San Antonio they must add the SAT/Bexar EDACS radio, and possibly an LCRA radio. Of course, Hays County requires the addition of an LCRA radio. I don't know what they do if the have to cover the wider area. Do they have to have their VHF radio, an Austin/Travis TRS radio, an LCRA radio, and a SAT/Bexar ProVoice radio? That's four! I don't recall seeing a trooper with that many radio's in the car.
North Texas is much easier. It's VHF and a Motorola 800mhz trunked/conventional radio programmed with several systems. I've never heard DPS on Richardson's EDACS though I have heard DPS on the Dallas UHF system but that's only beacuse the trooper sprung for his own UHF handie talkie.
Of course, the other 90% of Texas has full interoperability as they are all still on VHF. The metro areas are the ones that do not have interoperability.
Russell
Russell