902
Member
You will see more of these systems out there. I've just begun the process to explore a 9-site, 7-channel 700 MHz trunked system to replace several VHF systems which missed the mark in their deployment. While I'd like to do this on 800 MHz rather than on 700 (I see the impending 6.25 equivalency date on 700 as a threat for deployment rather than an opportunity - particularly if your budget forces you to buy mid-tier equipment which may cost as much as buying new to retrofit at a later time), there are presently no NPSPAC or general pool 800 MHz frequencies available in my area until either we re-pack NPSPAC and modify the plan (which would require the approval of 8 border states), or wait for the Nextel realignment. Anything we do here will most likely be on 700 MHz and will be trunked (that 7 channel system will replace 14 discrete VHF systems/ combiner nightmare, some simulcast, some stand-alone, some repeater, some simplex, each with a different footprint - classic haphazard deployment). If this ever gets off the drawingboard, it will tie into a master site controller in another community and will be a node of a larger, zoned system which would allow regionwide roaming on some interoperability talkgroups.DaveIN said:
P25 won't be just for Motorola. We've tested EFJ portable and mobile radio equipment within an all Motorola (VHF) quasi-P25 environment (wide pulse) and they worked well. An associate of mine tested a M/A-Com radio within his (800 MHz trunked 9.6k CCH) Motorola P25 system's environment and that worked as well. Each of the trunked system manufacturers is producing a basic P25 package, but have some proprietary enhancements (like Motorola's $4 ADP encryption, which, if you use it, marries you to the product). A group of us who work in public safety communications believe most 700 MHz public safety systems will be deployed in some basic form of P25, regardless of whether they are EFJ, M/A-Com or Motorola. Now that the ISSI component of P25 has been finalized and awaits publication, there is a standard on how all of these dissimilar elements communicate with each other, particularly with respect to infrastructure.
That said, there is nothing stopping systems from building systems which are more efficient than P25 on their primary operations channels. That's where OpenSky can fill in. OpenSky has the functionality of a five channel trunked system in ONE repeater (!). There are also microcell options where a box with connectivity could be bolted to a pole, hang an antenna on top of it and power it up and you have fill-in coverage (none of the other manufacturers are doing that... each seems to be interested in full sites at much greater costs). There is also a vehicle repeater system which essentially digipeats from a portable into the system if the unit can't hit the system directly (without user intervention). 'nuff of a sales job (I'm not a salesman), no scanner exists for this and right now OpenSky is proprietary, although the 4TDMA may become a P25 phase 2 solution. Don't forget 700 MHz users have a migration to one voicepath in 6.25 kHz equivalency date, even though the technoloy hasn't been developed (way to go, FCC). So some day in the future, P25 will change to something narrower. So we'll do all of this again eventially. Just simply monitoring as a hobby is going to become more complicated eventually.
Interesting theory about RS. Makes sense to test the DSP algorithm for future scanner hardware and it's easy enough to do. I don't see RS as being capable of handling a chip change or factory mod (if they had a 'bed of nails' fixture and could flash new firmware into their processor for 700 MHz) to all of their legacy products, either. IMO, their v1.3 depot upgrade a few years ago was disastrous.
