Charlie (and all),
The easiest way to explain P25 to someone new to radio is to compare the old analog cellphones to Nextel. If you have ever used a Nextel phone, P25 sounds and 'acts' like that , where as analog cellphones (which are no-longer produced) are more like analog conventional communications. Just about everything in Riverside County (as-far as public safety is concerned) is analog and mostly conventional. RSO is analog EDACS trunked.
P25 is a protocol that uses data sent over radio as opposed to voice, in order to use less spectrum bandwidth. (Very basically) when you talk on a P25 radio, your voice is converted to data packets which are sent over the air to the other radio which converts the data packets back to voice so the guy on the receiving end can hear what your saying. The data sent over the air takes up very little radio spectrum bandwidth. In the future with more radio users needing radio spectrum bandwidth, the use of data instead of voice will free up more room so everyone can do what they need to do.
The trade-off (at-least for now) is that the voice quality of P25 communications is poor and people are not used to it. There have been problems in other parts of the country with fire departments who have switched to exclusively P25 communications as part of a city-wide ‘upgrade’. The complaint is that when a firefighter is working in a burning building (for example) and is attempting to talk on the radio to other firefighters or the IC, he is completely unintelligible using a P25 radio. It was easier to hear said firefighter in the same situation on an analog system. I believe this is part of the reason that on San Diego’s RCS trunk system, 99-percent of the fire comms remain analog.
Riverside County is currently planning/building-out a NEW Motorola P25 trunking system to replace their aging GE EDACS system. I’m not sure if this new system will be JUST RSO (and other county-related users) or if other area agencies will also use (share) this system. Multiple agencies on large, complex county built/owned trunked radio systems appears to be a trend around the nation. Don’t be surprised if other local cities with their own radio systems like Murrieta, Hemet and Riverside City jump on the counties new system. It makes sense if you think about it. In terms of interoperability, everyone will be able to talk to eachother if need –be. In terms of saving money, the county’s radio system will be maintained by county employees as opposed to city employees. The FCC may force the cities to move to a P25 system in the future and the counties P25 system is an immediate solution to that.
As of right now, only the highest-end scanners have the ability to monitor P25 transmissions. When the new RSO P25 system goes on-line, you will all have to upgrade to scanners that will monitor P25. The Uniden 996T and 396T are good examples of scanners that will do this. I am not a big fan of Radio Shack products. In the mean-time, I really like and endorse Uniden’s non-P25 scanner, the BCT15.
For more information on P25, go to
www.google.com and enter “APCO P25” or just ask me…
~Chad (318)
P.S. Don’t confuse P25 with encryption, 800MHz rebanding, VHF fire narrow-banding or trunking… those are all other issues.