UHF's future in Texas?

[EAFrizzle]

A comment in the Austin thread has me wondering why there's been such an exodus of PS users from UHF in Texas in the past few decades. Are 700/800 MHz characteristics that much better than UHF for most uses? Or is it just a matter of consolidation and simplification to prep for a better statewide system in the future?

 

[nd5y]

Are 700/800 MHz characteristics that much better than UHF for most uses?

Generally no. UHF can be better in some cases and 700-900 MHz can be better in some cases.

The main reason is because public safety in a lot of places moved to trunked systems and there is not enough space for new trunked systems on UHF.
There are only a few frequencies on 453/458 and 460/465 MHz reserved for public safety.
769-775/799-805 MHz and 851-854/806-809 are public safety only with other frequencies availbe in 854-861/809-816 MHz section.

 

[Project25_MASTR]

There hasn't really been an exodus away. The major cities were the primary users of UHF and several of them had access to T-Band which everyone has been trying to migrate away from since the FCC has been saying we are loosing T-Band for nearly a decade now. More importantly though there is a ton of spectrum available in 700 MHz and 800 MHz that is reserved specifically for public safety. So it made a lot more sense to build out larger public safety systems on 700/800 MHz versus UHF in those cities.

Also worth noting, 800 MHz was one of the first bands used commonly for trunking and several manufacturers didn't offer trunking solutions in VHF/UHF until much later (look at the XTS3000 from Motorola as an example for P25 trunking as it was supported on 800 MHz but not on VHF or UHF). In fact, P25 trunking on UHF and VHF is known as Other Band Trunking (OBT) due to the lack of standard splits and it being a legacy term from Motorola's SmartNet systems when that option was offered in the mid-90's. There are standard splits in UHF but depending on where you are in the band they can be all over the place (10 MHz for the federal stuff, 5 MHz for the traditional 450-470 range and 3 MHz for T-band).

 

[motorola_otaku]

The 453 and 460 channels didn't go to waste, either... BTU and Cy-Fair ISD both built trunking systems on or adjacent to frequencies vacated by the City of Houston, and Cypress Creek FD hoovered them up as soon as they were available.

Historically Houston, Dallas, and Austin all shared the same 453 and 460 MHz frequencies (DFR and HFD to this day both still use 460.575 for backup fire station alerting) and because they were all licensed for ERPs sometimes close to half a kilowatt interference during tropospheric ducting band openings was common; Austin in particular because of its geography was particularly susceptible to ducting interference. 700 MHz can still be "ducted" but because, as mentioned, the pool of available frequencies is much larger it was much easier to coordinate frequency assignments to reduce interference potential.