King County Transit P25 - observations

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Feed Provider
Feb 15, 2002
Bragg Creek, Alberta
Hi folks,
I left Unitrunker running on the above system for a good while, while I was in your fair city of Seattle watching my team get its clock cleaned 3 nights in a row (I am starting to hate that Fernando Rodney theme music), and I can provide some info I observed on simulcast site 001-001:

- Huge amount of data calls on this system. I wouldn't be surprised if the screens on buses (and I presume on trains too, but I only rode the buses) that show the next stop are either sending or receiving this info over the system.
- Data calls are exclusively happening on Phase 1 frequencies.
- Voice calls are almost exclusively happening on Phase 2 frequencies, with a small handful of grants on P1 frequencies. (See below for my list of frequencies.)
- The same frequencies (with only two exceptions, see the list) are used for the Phase 1 and Phase 2 parts of the system. I've never seen this done before, but this means that if a data call is using a frequency, it's taking up "both slots" of the P2 freq. A grant for LCN 01-1282 is for 770.01875, for Phase 1 operation. A grant for LCN 03-1282 is for 770.01875, Phase 2 Slot 1. A grant for LCN 03-1283 is for 770.01875, Phase 2 Slot 2. This is normal and expected behavior, but it's weird to see them use the same frequencies for P1 and P2 operations simultaneously. (Well, not simultaneously, but you get what I mean, I hope.)
- Talkgroup 28047 used Phase 1 exclusively.
- All other talkgroups I monitored (which included 28001 up to 28049; I didn't get hits on the higher TGs) used Phase 2 exclusively.

The (non-CC) frequencies on site 001-001 are as follows and use Phase 1 (P1)
and Phase 2 (P2) where noted.
Freq		P1	P2
769.51875	x	x
769.76875	x	x
770.01875	x	x
770.26875	x	x
770.50625	x	x
770.51875	x	x
774.13125	x	x
774.14375	x	x
774.38125	x	x
774.39375	x	
774.64375		x
I just thought this information was neat; do with it what you wish.


Feb 24, 2001
I still would really like to know why KCMT is *still* using X2-TDMA and not P25 Phase 2. You would think they would migrate to Phase 2.

Phase 2 sounds WAY better than X2-TDMA... unless that is the fault of the decoding in the PSR-800...


Dec 19, 2002
The simple facts.

1. The KC Metro TRS has absolutely nothing to do with South Sound. It is used by Metro.

2. The Pierce County 700 TRS does have a site in King County. The Pierce Transit buses use this site on their routes to Seattle.

3. Neither of these systems have anything to do with the King County TRS or the new PSERN system.

4. scannerizer's source can be found here: Let me google that for you
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