Philly Phase 2???

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radio3353

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On another forum, I mentioned that Philly is a Phase I simulcast system (this was in response to somebody saying the Broadcastify feed audio was choppy.) Another poster corrected me and said Philly was Phase II. I did not think this was correct, but when I looked at the RR database sure enough it says Phase II. However, I can still hear Philly on my PRO-106 (tested it this afternoon sitting outside Engine 62) and it was picking up FD fine, yet the PRO-106 is not Phase 2 capable. I also looked at the data for the FD North Band feed and it says a Uniden Home Patrol 1 scanner is being used, also not Phase II capable.

So before I send a correction to the database admin, is Philly Phase I or Phase II? I did not think the Phase II conversion happened yet.

Thanks.
 

GTR8000

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As the system information note in the database states, the ASTRO 25 core is TDMA (Phase II) capable, however due to the fact that the older subscriber units don't support TDMA, all talkgroups continue to operate in FDMA (Phase I) mode.

Motorola ASTRO 25 systems are always Phase I FDMA capable, including those systems that are in the database as Phase II TDMA. The only difference between the two, for practical purposes, is whether or not the system has the software option for Phase II TDMA. System administrators can choose whether to "strap" (lock) talkgroups to Phase I FDMA only, or Phase II TDMA only, depending on the needs of the users. There is an additional software option called Dynamic Dual Mode (DDM) which allows talkgroups to operate with preference for Phase II TDMA, but if an older radio affiliates, can revert to Phase I FDMA to support it.

In plain English: They bought the system with the Phase II TDMA option but haven't used it yet because none of the old radios they're using can do Phase II TDMA. They would need to buy new radios (such as the APX models) which support Phase II TDMA before it would be of any use.

Bottom line: If the system shows to be Phase II TDMA capable (which Philly's does based on the bandplan it's broadcasting), then that's how it gets listed in the database. The more important thing to look at is whether the talkgroups are FDMA (D) or TDMA (T). If they are all FDMA (D), then a scanner that only decodes Phase I FDMA will work just fine with those talkgroups.

No correction to the database is needed. The system is Phase II capable, just not using it yet.
 

GTR8000

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Because the system is a Phase II system. The fact that no talkgroups are using TDMA yet doesn't change that.

This is our official policy:

Trunked systems shall always be entered with the “highest level” mode of operation for which it is confirmed to be capable. For example, enter a Project 25 system as “Phase 2” type if it is confirmed to be Type 2 capable even if it has no TDMA talkgroups confirmed in use yet.
 

ocguard

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I understand your explanation, but why call it Phase II if it isn't? It obviously creates confusion.
There should be no confusion. The talk group tables list Phase 2 talk groups with a "T" to denote TDMA. Standard FDMA talk groups are listed as "D." There are many Phase 1 systems that carry Phase 1 talk groups or talk groups that revert to Phase 1 when a non-TDMA subscriber unit affiliates.
 
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