P25 Phase 2

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kd8eyf
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P25 Phase 2

Postby kd8eyf » Fri Aug 26, 2011 7:51 am

Is the standard finalized yet? If not is there a deadline?
2 timeslot TDMA / AMBE2 , sounds like trbo to me. Whats the difference?

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Re: P25 Phase 2

Postby mr.syntrx » Fri Aug 26, 2011 8:55 am

For a portable radio, the main difference is $5000 :baby:
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Re: P25 Phase 2

Postby motorola_otaku » Fri Aug 26, 2011 12:00 pm

Right now the only Phase 2 solution on the table is Motorola's X2 TDMA system. It's essentially the same thing as Astro25 but with 2:1 TDMA capability. The control channel is Phase 1 and the vocoder is still IMBE. Talkgroups within the system can be programmed to use FDMA, or certain RIDs can be flagged as non-TDMA so when they affiliate with a particular talkgroup it will roll back from TDMA to FDMA. I don't know if it's compatible with SmartX, where you have an Astro25 system and an analog Smartzone system sharing the same zone controller with full talkgroup cross-system capability.
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Re: P25 Phase 2

Postby kd8eyf » Mon Feb 27, 2012 7:39 am

trying to wrap my head around the differences betweek phase 1/2
i started a spreadsheet
need help checking and finishing
http://tinyurl.com/7lj9pd4

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Re: P25 Phase 2

Postby motorola_otaku » Mon Feb 27, 2012 2:44 pm

Just to make things even more interesting, there's now "compliant" Phase II and X2 TDMA. Both use a normal FDMA Phase 1 control channel and can support mixed FDMA/TDMA voice, but the TDMA protocol is handled completely differently between the two. Current APX radios support both, but Harris and other manufacturers' radios will only support compliant Phase II. On the :wacker: end the PSR800 is the only scanner that will decode X2, and nothing out currently will decode compliant Phase II.
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Re: P25 Phase 2

Postby Wowbagger » Mon Feb 27, 2012 3:49 pm

motorola_otaku wrote:Right now the only Phase 2 solution on the table is Motorola's X2 TDMA system. It's essentially the same thing as Astro25 but with 2:1 TDMA capability. The control channel is Phase 1 and the vocoder is still IMBE.


Wrong.

The control channel *can be* Phase 1 style, OR can be a TDMA channel, either occupying both time slots OR allowing the second time slot to be voice.

The vocoder is AMBE2, running at about half the bit rate as Phase 1 - that's how they can do 2 slot TDMA in the same total number of bits per second.
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Re: P25 Phase 2

Postby ka8ypy » Mon Feb 27, 2012 4:01 pm

motorola_otaku wrote: On the :wacker: end the PSR800 is the only scanner that will decode X2, and nothing out currently will decode compliant Phase II.


My PSR800 will, PG is playing with true phase II and I am picking it up just fine.
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Re: P25 Phase 2

Postby motorola_otaku » Tue Feb 28, 2012 12:10 am

Wowbagger wrote:Wrong.

The control channel *can be* Phase 1 style, OR can be a TDMA channel, either occupying both time slots OR allowing the second time slot to be voice.

I.. what. How does that even work without incurring delays in channel grants?

Also I'm looking at your own company's application note on P25 control channels and don't see this mentioned. Time for an update maybe?

ka8ypy wrote:My PSR800 will, PG is playing with true phase II and I am picking it up just fine.

I thought PG was X2? They were on the air before the Phase II standard was even finalized.

Anyway, one way to tell for sure is a CC data dump from Unitrunker (this note comes from the guy who wrote UT, btw:)
If any identifier updates have "90" in the second byte, it's a Motorola X2. Otherwise it's Phase 2. If you're running Unitrunker, you can look at the decode logs.
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Re: P25 Phase 2

Postby Wowbagger » Tue Feb 28, 2012 10:49 am

motorola_otaku wrote:
Wowbagger wrote:I.. what. How does that even work without incurring delays in channel grants?

Also I'm looking at your own company's application note on P25 control channels and don't see this mentioned. Time for an update maybe?


The worst case delay on a channel grant using only one slot of a channel as the control channel would only be about 170ms - the time to allocate all the channel resources (talk channel) would likely be longer. You aren't going to notice this.

As for the docs: Remember, what we are talking about here is Motorola's proprietary extension, not the APCO Phase 2 standard. That's why it's not on the main docs.
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Re: P25 Phase 2

Postby ka8ypy » Tue Feb 28, 2012 5:57 pm

motorola_otaku wrote:

ka8ypy wrote:My PSR800 will, PG is playing with true phase II and I am picking it up just fine.

I thought PG was X2? They were on the air before the Phase II standard was even finalized.


PG is X2 but they have been playing with true phase II on the system (2 sites and about 20 - 25 radios) as well in preparation of an upcoming upgrade to Phase II per the contract.
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