Motorola P25 systems - should all be listed as X2?

[Jay911]

Hi,
I have been doing P25 monitoring and analysis in a number of places in the past few months, as part of a hobby. One thing I've discovered is that every Motorola system I've encountered so far is sending X2-TDMA identifiers (band plan descriptors) even if the system is configured for FDMA - in that case, it's sending them with "1 slot 12.5kHz" configuration.

Should these systems be submitted to be reconfigured as X2 systems in the DB, or should the DB only show X2 for systems which are actually using TDMA functionality/multiple slots per frequency?

On one hand, the systems are definitely putting out data which a non-X2-compatible scanner will not understand (and conversely that an X2-compatible scanner will be able to take advantage of, one would presume).
On the other hand, as has been seen previously, marking them X2 might put them "out of reach" of some scanners as some software packages consider those systems incompatible with regular scanners, and will not download them.

Looking for the lead admin to provide some input on this and I'll proceed from there. Thanks.

 

[GTR8000]

The database should only reflect what is actually in use, not what is possible.

If a previously all-FDMA system starts operating in X2-TDMA or Phase II TDMA mode, the system can be easily updated with a submission to reflect the reality.

By your logic, any Motorola P25 system that is at ASTRO 25 System Release 7.11 should be in the database as a Phase II system, since they are capable of operating in Phase II TDMA mode, regardless of whether they actually are.

 

[loumaag]

...
On one hand, the systems are definitely putting out data which a non-X2-compatible scanner will not understand (and conversely that an X2-compatible scanner will be able to take advantage of, one would presume).
...

Hopefully Eric will stumble across this and comment; however, I am curious as to what advantage a PSR-800 would have, knowing in advance, a system was X2 capable? It does not differentiate between P25 systems at all, if a X2 transmission happens, it just decodes it.

 

[jim202]

Did you ever think that in Motorola's mind this could be one way they are trying to keep the competition's radios off of their system?

 

[lep]

Hi,
I have been doing P25 monitoring and analysis in a number of places in the past few months, as part of a hobby. One thing I've discovered is that every Motorola system I've encountered so far is sending X2-TDMA identifiers (band plan descriptors) even if the system is configured for FDMA - in that case, it's sending them with "1 slot 12.5kHz" configuration.

Should these systems be submitted to be reconfigured as X2 systems in the DB, or should the DB only show X2 for systems which are actually using TDMA functionality/multiple slots per frequency?

.

No, when an overzealous contributor sumitted my local system as X2 TDMA based on a press release, the Uniden mirror download blocked that system until the helpful "update" was undone.

How would the 'marking of all P-25 systems as X2' (based on your hobby observation) aide anyone in monitoring?

 

[loumaag]

Did you ever think that in Motorola's mind this could be one way they are trying to keep the competition's radios off of their system?

Well, if so, it must be in some salesman's mind alone. Since all P25 radios would still be able to transmit in non-X2 (or non TDMA mode at all) and therefore revert the TG to FDMA.

 

[Jay911]

Hopefully Eric will stumble across this and comment; however, I am curious as to what advantage a PSR-800 would have, knowing in advance, a system was X2 capable? It does not differentiate between P25 systems at all, if a X2 transmission happens, it just decodes it.

There's more to the X2 spec than just voice grants. Discussions here on RR and elsewhere imply that some scanners are reacting differently to the various TSBKs that come from a Motorola-branded P25 system.

It was a simple question, folks. There was no need for the hostile remarks (not from you, Lou; from others).

 

[mikewazowski]

I don't see any point in marking a system as X2 or even Phase II if no tdma talkgroups have been seen.

It might just be a default bandplan setup that came from the factory or future use.

 

[loumaag]

I don't see any point in marking a system as X2 or even Phase II if no tdma talkgroups have been seen.

It might just be a default bandplan setup that came from the factory or future use.

I like that answer, it reminds me that as of some version of software (don't remember which one) all Type II systems were capable of P25 CAI voice but we didn't mark them that way unless they actually used it. Also, how about the other side of the coin, take the SD State system, it is a Type II that uses only P25 CAI so it was so indicated, no analog allowed.

 

[mikewazowski]

You needed a Smartzone controller to be able to run digital.

As you said, even though the controller supported digital and advertised it as doing so on the control channel, it didn't mean there was any digital activity on the system at all.

 

[WayneH]

You needed a Smartzone controller to be able to run digital.

No you didn't. You could do it with a 6809 provided you gave up either Simulcast or connecting consoles. This is due to physical limitations of connections to the controller.

I used to think the same thing until a ST explained it.

 

[N2ICV]

I wish you all would stop using X2-TDMA..It's P25 Phase II ! X2 is done.
Motorola ASTRO 25 System Release 7.11 is a Phase II system, Not "X2".
The Motorola workers that I know say that all systems are P25 Phase II , NOT X2.

 

[loumaag]

I wish you all would stop using X2-TDMA..It's P25 Phase II ! X2 is done.
Motorola ASTRO 25 System Release 7.11 is a Phase II system, Not "X2".
The Motorola workers that I know say that all systems are P25 Phase II , NOT X2.

I suggest you talk to them again and tell them to go back to school, class, whatever. Since I don't work for Motorola, I can only speak to the fact that my PSR 800 (which decodes X2 but not Phase II) is picking up the local system being built out. :roll:

 

[GTR8000]

I wish you all would stop using X2-TDMA..It's P25 Phase II ! X2 is done.
Motorola ASTRO 25 System Release 7.11 is a Phase II system, Not "X2".
The Motorola workers that I know say that all systems are P25 Phase II , NOT X2.

That is absolutely incorrect.

Motorola still very much supports X2-TDMA, and there are enough systems on the air to prove it. 7.11 gave systems the ability to operate in Phase II TDMA mode, however that doesn't mean they are yet. Systems that are operating in X2-TDMA were not forced to change to Phase II TDMA with the upgrade to 7.11.

Like Lou said, the guys who told you that are misinformed, or you misunderstood them. Either way, X2-TDMA is alive and well.

 

[N2ICV]

But you guys have Phase II systems as X2 and that is wrong. a X2 radio cant talk to a Phase II radio right? X2 and Phase II are two different formats.
And I never said X2 is unsupported, Im saying all systems going on now are Phase II . There will be NO more new X2 systems.
Here in NJ the New Jersey Public Safety Interoperability Communications (PSIC) Network Trunking System, Statewide, New Jersey - Scanner Frequencies and the Camden County (Project-25) Trunking System, Countywide, New Jersey - Scanner Frequencies and are incorrectly maked as X2 when they are Phase II systems!

 

[N2ICV]

I suggest you talk to them again and tell them to go back to school, class, whatever. Since I don't work for Motorola, I can only speak to the fact that my PSR 800 (which decodes X2 but not Phase II) is picking up the local system being built out. :roll:

If you dont work for Motorola, then dont tell me what to tell them, thank you.

 

[RadioDitch]

But you guys have Phase II systems as X2 and that is wrong. a X2 radio cant talk to a Phase II radio right? X2 and Phase II are to different formats.
And I never said X2 is unsupported, Im saying all systems going on now are Phase II . There will be NO more new X2 systems.
Here in NJ the New Jersey Public Safety Interoperability Communications (PSIC) Network Trunking System, Statewide, New Jersey - Scanner Frequencies and the Camden County (Project-25) Trunking System, Countywide, New Jersey - Scanner Frequencies and are incorrectly maked as X2 when they are Phase II systems!

I think there's a misunderstanding. There is a difference between Phase II TDMA and X2-TDMA, and no one is arguing that both are supported or what the 7.11 update did. Mike is correct though that new Motorola hardware currently being shipped is Phase II TDMA, and that Motorola is no longer producing new hardware with X2-TDMA.

What I believe is being said is that it would seem that the default in the database is to list a Phase II TDMA system as P25 X2-TDMA. And this seems to be true, especially with the new 700MHz systems in New Jersey. But it is not correct to do so since there is a difference.

Also if you have a PSR-800 it is useless on a P25 Phase II TDMA system. The PSR-800 only supports X2-TDMA. Currently there is no scanner on the market which can decode P25 Phase II TDMA.

 

[GTR8000]

What I believe is being said is that it would seem that it is default in the database is to list a Phase II TDMA system as P25 X2-TDMA. And this seems to be true, especially with the new 700MHz systems in New Jersey. But it is not correct to do so since there is a difference.

Except for the fact that thus far, all talkgroups on the NJ PSIC system have been operating in X2-TDMA mode, not Phase II TDMA mode. It really doesn't matter what the system is supposed to be on paper, what matters is reality. I believe the same is true with Camden's new system, since people are identifying talkgroups. Setting that system as Phase II TDMA in the RRDB means it won't work with any scanner, since as you've already noted there is no scanner that currently supports Phase II TDMA. Obviously there are people listening to the system, which indicates the reality is that it is operating with X2-TDMA, not Phase II TDMA.

Any hardware that supports Phase II TDMA is also capable of supporting X2-TDMA. I think the misunderstanding is that most new systems would probably have no reason to use X2-TDMA now that Phase II TDMA is available. That doesn't mean they can't use X2-TDMA, however. I have not seen any official statement from Motorola stating that support for X2-TDMA is being removed from their P25 hardware.

 

[RadioDitch]

Except for the fact that thus far, all talkgroups on the NJ PSIC system have been operating in X2-TDMA mode, not Phase II TDMA mode.

I wasn't referring to the PSIC actually, which is supposed to be Phase II when fully operational. However it's operating P25 Phase I FDMA during development and testing, not X2. As far as I'm aware, the only TDMA of any kind thats been received on the system thus far was a telephone interconnect test on June 25th. But yes, it is supposed to go X2 temporarily before going Phase II.

However, the buildout-phase systems in Union County, Ocean County, and several others are listed as X2-TDMA which they will not be once on-air.

 

[loumaag]

If you dont work for Motorola, then dont tell me what to tell them, thank you.

And with that said, don't tell us what to put in the database when you obviously have no idea what you are talking about.