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Thread: Phase II discussion

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    Default Phase II discussion

    Quote Originally Posted by PhaseII View Post
    ~ It's just a shame that GRE and Uniden haven't come out with a Phase II capable scanner yet ~
    sign0006.gif I know, sorry, but just FYI...



    http://www.youtube.com/watch?v=Mf8oyD0LwjI
    Andrew


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    I was given to believe that "X2" is Motorola's in-house version of "Phase II" although I think it was released well before the APCO P2 standard was actually finalized?

    In any case, technically APX radios do X2 not Phase 2

    X2 Help Screen.jpg
    Andrew

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    APX radios can do both.

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    Yes, X2 was also 9600bps, while the Phase II standard when it finally came out specified 12.5bps. This is why XTS/XTL radios cannot be field upgraded to do Phase II. Motorola was not happy about that...neither are their customers who were told their XTS/XTL radios would be Phase II capable!

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    Quote Originally Posted by Magnus View Post
    APX radios can do both.
    Ah okay, must be the old firmware version that was in the radio when the codeplug I'm looking at was read, it's an APX born in May 2010 with R04 firmware which probably explains why I don't see Phase II?
    Andrew

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    Quote Originally Posted by Ice-T View Post
    This is why XTS/XTL radios cannot be field upgraded to do Phase II.
    I'm not going to profess to be a know-it-all Cowthief here, but I've heard pretty much the same as you have -- except the anger and frustration expressed by the customers is beyond belief, and a possible solution IS being worked on. I guess we'll have to wait and see.

    Very angry customers on very large systems...Lots of $$$ involved. The "buy a APX6000 instead" line isn't working on them, especially after they JUST bought a large quantity of 8MB XTS2500s, which are about to go the same way as the 4MB 2500.

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    The only redeeming feature, at least so I've been told, is that the APCO Phase II standard is backwards compatible, that is to say that an FDMA radio will still be able to use a TDMA system?

    I agree though, a lot of customers are not going to be happy... there are government agencies over here that are STILL buying XTL/XTS radios brand new!
    Andrew

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    I'm not sure about the capabilities of the DSP in the ASTRO25 line, but I know for certain there's plenty of memory left over for an alternate codec (AMBE+2) in the 8MB radios.

    The existing IMBE codec resides in a 320KB partition, while the oldschool ASTRO radios managed to get by with 256KB.

    Aside from there being lots of extra space after the last partition, there are also some useless partitions which were never implemented, which could be freed up for other things.

    What remains to be seen is whether or not there's enough DSP RAM for both codecs to be loaded at the same time. i.e. ALL OR NOTHING Phase II support, with no IMBE.

    All hypothetical of course, assuming Motorola can come up with a Phase II solution for ASTRO25 gear.

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    Where is that system in the video?

    I know of no KC Metro system other than the MAARS system.

    EDIT: Nevermind, I figured out it was King County, Washington State not Kansas City metro in Missouri.

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    Quote Originally Posted by PhaseII View Post
    That should read 12 kbps, not 12.5bps.

    Motorola have no one to blame but themselves. They put all their eggs in the X2 basket, believing they had enough influence over the P25 committee so that X2 would be outright adopted as the Phase II standard. It was not, and they got burned. More importantly, many customers got burned, believing they were purchasing Phase II upgradeable XTS's.
    You're right...I actually wrote it as '12.5KHz' at first, lol. Old habits. Most people don't realize it, but Motorola due to their early adoption of IMBE-based 'Phase I' digital, defined much of the P25 standard since it's inception, and are definitely the most influential manufacturer of the P25 committee. I'm not sure what dealings went on in the 9.6 vs 12 debate, but I was somewhat surprised they lost that one. It was definitely short-sighted of them to not design 12bps capability into the XTS/XTL series as a backup plan. I guess they figured if you build & sell enough of them, the committee would follow.

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    What I don't get is this - the DSP 56000 chip used in the first generation ASTROs (ASTRO Saber and XTS3000) was used in ADSL modelsdoing fancy **** QAM and other modulation schemes running tens of megabits that are far more complicated than P25 Phase 2...

    So why the hell is a jump from 9600bps (C4FM 4800 baud) to 12.5kbps a problem!?

    There has to be more to this than meets the eye.

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    Because they have to...

    1 hire some better coders
    2 sell less APX's
    3 start from scratch with there DSP code

    Those are my guesses, I'm fairly certain the DSP chip in the Patriot IC is more than capable.

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    So...

    X2 = VSELP
    Phase II = IMBE

    ?

    Kudos if you get my drift...

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    Quote Originally Posted by d119 View Post
    So...

    X2 = VSELP
    Phase II = IMBE

    ?

    Kudos if you get my drift...
    I believe I get your drift

    Phase III will be built-in ADP, as part of the ASK, of which is also required to configure the encrypted Moto-proprietary control channel. Uhhmm Hmmm

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    So Phase II still uses Phase I for simplex, correct?

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    Quote Originally Posted by KE7JFF View Post
    So Phase II still uses Phase I for simplex, correct?
    Yes. It has to as there's no timing reference for TDMA on simplex.

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    In speaking with the TIA folks, they have had discussions regarding a TDMA control channel, TDMA data (currently data on a system utilizes FDMA) as well as TDMA conventional. They did say they are currently not getting much response from the manufacturers. As for the 9.6k vs 12k, some of the other vendors were able to sway TIA away from 9.k. It is also my understanding that TIA had some voice quality concerns about two voice paths in the same bandwidth as one FDMA. I can tell you i strongly prefer the sound of Phase II over X2. In our region both are currently on the air. X2 always sounded "pinchy" to me. Phase II sounds exactly like Phase I to my ear.

    Honestly, i do not expect alot of development of P25. Most of the industry is looking towards LTE and creation of PTT over it. The TIA guys referenced "P25 Phase III" but said it was essentially dead in the water due to lack of interest.

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    Why would anyone even need a TDMA control channel? The whole purpose of TDMA is to share spectrum with other users, on the same frequency. (compete for time-slots). A control channel would not benefit from this unless the TDMA scheme was being implemented in an area with heavy congestion, and frequency re-use was necessary in close-quarters. Even then, it would limit range and require a synchronized time signal. If that synchronized time signal were to fail (or link were to be disrupted), the sites would have to fall back to FDMA modulation or risk being out-of-phase.

    No wonder the vendors have no interest in TDMA control channels.

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    It would give the user one more talkpath for voice. but yea i dont see much benefit. What are you going to do, get rid of 1/2 a voice channel? I forsee LTE killing the public safety scanner market. Fortunatly that is many years away.

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    Quote Originally Posted by XPR8300 View Post
    It would give the user one more talkpath for voice. but yea i dont see much benefit. What are you going to do, get rid of 1/2 a voice channel? I forsee LTE killing the public safety scanner market. Fortunatly that is many years away.
    I wonder how Mr. Lindsay C. Blanton III feels about that.

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    If you ask me there's just way too many platforms out there already, between APCO P25 (Phase I, II & III (if it ever happens)), X2, TRBO, TETRA/ZEON, NXDN, GSM-R and the list goes on...

    I wish somebody would just pick a standard already...
    Andrew

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    Quote Originally Posted by Bigfella237 View Post
    If you ask me there's just way too many platforms out there already, between APCO P25 (Phase I, II & III (if it ever happens)), X2, TRBO, TETRA/ZEON, NXDN, GSM-R and the list goes on...

    I wish somebody would just pick a standard already...


    Well said!

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    Quote Originally Posted by Bigfella237 View Post
    If you ask me there's just way too many platforms out there already, between APCO P25 (Phase I, II & III (if it ever happens)), X2, TRBO, TETRA/ZEON, NXDN, GSM-R and the list goes on...

    I wish somebody would just pick a standard already...
    It is time for my second favorite XKCD comic:

    http://xkcd.com/927/

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    Quote Originally Posted by Bigfella237 View Post
    If you ask me there's just way too many platforms out there already, between APCO P25 (Phase I, II & III (if it ever happens)), X2, TRBO, TETRA/ZEON, NXDN, GSM-R and the list goes on...
    Wonder if Uniden or GRE are developing something that can do everything and keep Lindsay happy?

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    If Lindsay is 'kept happy' there won't be anything left to pick up on a scanner! (But that's a discussion for a whole other thread (or five)?)

    I doubt that scanner manufacturers will ever support anything beside the open standards, it would simply cost too much to licence them for TRBO, NXDN etc., scanners would cost the same as the equivalent two-ways? And who wouldn't have a Motorola radio over a Uniden scanner if the price was comparable?
    Andrew