- Nov 16, 2004
Correct, you need to program each site into a P25 trunked system. You could also just lock-out (avoid) the active control channels as they will not have voice traffic on them.
Yes, you will need a new scanner.
It looks like new amended applications have been submitted. They were requested to submit an RPC approval letter from region 17 (Indiana) and they have now included that letter.
Of note, they still only have 4 frequencies for Campbell County (even though the control channel is advertising frequencies not on the application) and they only have the P25 TDMA emission designator (9K80D7W) for the frequencies. Most systems also include a Phase I designator being that the control channel is always Phase I and the system should be capable of reverting automatically to Phase I if it is keeping with the P25 standards.
Another note, they are already transmitting on frequencies that they have not yet been licensed for.
They may be operating under a blanket authorization from the APCO Regional Planning Committee and/or FCC until they identify the frequencies which work best in that particular location. Ohio MARCS built out their system the same way, although being a statewide system they had a license which covered the entire state. Didn't really cause any problems at the scanning end, as the control channels were licensed.What are they trying to do here? Just wing it?
I will need to reread my TIA documents. I thought automatic 'fallback' to Phase I (FDMA) was a requirement of the Phase II (TDMA) standards. Also, the control channel is operating FDMA (I also though this was a Phase II requirement) and they are already transmitting data on the system in FDMA mode.And as to the statement about any P25 system having to have FDMA use to be compliant... NOPE. Phase II is a standard all its own. You can go pure TDMA from the rip and not ever have any need for FDMA on any part of it. If you have need of interop with another system that is FDMA, or analog, you set up patching, or ISSI linkage. There is no part of anything saying that you must use a DDM set up to meet any part of any standard.
The control channel does transmit in Phase I which is part of the standard, and evidently it doesn't require that the license include FDMA emissions. As far as automatic fallback, I don't believe that's a requirement or part of the standard, just a handy feature of Motorola systems. If all the users are on TDMA and FDMA isn't required there's no need to have it on the license.I will need to reread my TIA documents. I thought automatic 'fallback' to Phase I (FDMA) was a requirement of the Phase II (TDMA) standards. Also, the control channel is operating FDMA (I also though this was a Phase II requirement) and they are already transmitting data on the system in FDMA mode.
The FCC applications were returned today so it looks like more delays.
I know about ISSI, but it's not going to happen on the MARCS end unless someone else pays for it. Been down that road already. It's better than patching but is also an imperfect solution (there are limitations based on the number of talk paths). It would seem silly, though, to run a signal from the NKY system all the way to the zone controller, through the ISSI switch and back down to Cincinnati so that two radios feet apart on the same incident scene could talk to one another.Tom, there is also ISSI linking that can be done. FDMA on the SAFE-T and MARCS-ip sides and TDMA on NKYRRS