Support for TDMA P25 Phase II

[Raccon]

Is TDMA a requirement for P25 Phase 2? The last time I read something on phase 2 it only mentioned using a narrower bandwidth - 6.26KHz to comply with the 2013 narrowbanding rules. I didn't see anything about having to be TDMA. Now I may be behind the times, but isn't TDMA an old technolgy, a modulation format, that cell companies got away from because of technical limitations?
A new wide area P25 system going up in my area on 700MHz and they are using 6.25MHZ width with LSM.
Also, if TDMA were a requirement, wouldn't it be an open format that reciever manufacturers could adopt for the open market using P25?
BG..

The term 'TDMA' is too generic as there are many different modulation formats that are employed in TDMA systems, with new ones still being developed/implemented.

 

[N_Jay]

The term 'TDMA' is too generic as there are many different modulation formats that are employed in TDMA systems, with new ones still being developed/implemented.

Close:

Yes TDMA is too generic to use in the form it is being used.
There are many different TDMA based air interface formats,
that use many different modulation formats,
and,
many different TDMA channel coding formats,
that,
carry many types of information,
some of which are vocoded voice,
and
those you many different vocoder formats.

 

[ButchGone]

Certainly not trying to be confrontational NJay, but the new P25 700MHz system being built in Tennessee is in fact using 6.25KHz spacing and it is not TDMA or anything like it.
It is licensed to the City of Chattanooga (got federal grants to build regional system).
As an example, call sign WQKQ-452 shows:

ULS License - Trunked Public Safety 700 MHz License - WQKQ452 - City of Chattanooga - Locations Summary

There are several other call signs listed for the City of Chattanooga that clearly show they are using 6.25KHZ spacing for this new system. It's all P25, LSM format.
It has nothing to do with the way a Uniden scanner hears it.
That's why I am not convinced there is a mandate to use TDMA for P25 Phase 2.
If there is such a mandate, please give a link to the information! Where is this written?
I know there can be a lot of confusion, because radio manufacturers are trying to make the sale by telling public safety agencies half-truths. Like the one about "the government is mandating digital by 2013!"
Motorola and Kenwood are making a killing by selling unsuspecting public safety agencies TRBO and NXDN that are not interoperable with anyone else in their regions.
Cheers!

 

[greenthumb]

All of the frequencies on that license show 8K10F1E which is a bandwidth of 8.10 kHz, not 6.25 kHz, and is a common P25 FDMA emission as listed on several Motorola P25 FDMA-only products.

http://www.motorola.com/staticfiles...ic Files/R3-4-2003K_XTS2500_1.pdf?localeId=33

Nobody today is shipping FDMA P25 voice at 6.25 kHz bandwidth. There isn't a mandate for TDMA for 700 MHz 6.25e narrow-banding, but that is how all of the manufacturers will be shipping it.

P25 phase II will be TDMA. Look at the docs.

 

[N_Jay]

Certainly not trying to be confrontational NJay, but the new P25 700MHz system being built in Tennessee is in fact using 6.25KHz spacing and it is not TDMA or anything like it.
It is licensed to the City of Chattanooga (got federal grants to build regional system).
As an example, call sign WQKQ-452 shows:

ULS License - Trunked Public Safety 700 MHz License - WQKQ452 - City of Chattanooga - Locations Summary

As pointed out, 8K10F1E is a standard emission designator for P25 Phase 1.
I don't know where in that license you get any indication that the system is 6.25 kHz.

There are several other call signs listed for the City of Chattanooga that clearly show they are using 6.25KHZ spacing for this new system

How so?
Please explain what you are interpreting to indicate it is 6.25 kHz.

It's all P25, LSM format.

I am not disagreeing with that.

It has nothing to do with the way a Uniden scanner hears it.

It is P25 Phase1, that is why the Uniden receives it.

That's why I am not convinced there is a mandate to use TDMA for P25 Phase 2.

You haven't read what I posted carefully enough.

700 MHz will need to be 6.25 kHz or 6.25e (2 slot TDMA at 12.5 kHz).
All currently implemented systems are (or should be) working under STAs or waivers to allow 12.5 kHz operation until 6.25e can be achieved.

There is nothing here to convince anyone of anything else.

If there is such a mandate, please give a link to the information! Where is this written?

Check out the rules written by any of the 700 MHz Regional Planning Committees (RPCs)

I know there can be a lot of confusion, because radio manufacturers are trying to make the sale by telling public safety agencies half-truths.

There is far more confusion caused by people who try to explain things they "half-understand".

Like the one about "the government is mandating digital by 2013!"

I work with this stuff every day, and talk to the vendors all Te time, and I have NEVER heard that first hand, but I can't count the number of times it has been repeated to me second hand.
It is a classic case of whisper down the lane.

Sure, the sales guy may not do the best job explaining, or over simplifies, but the rampant repeating of these falsehood happens far more on the user side then on the vendor side.

Motorola and Kenwood are making a killing by selling unsuspecting public safety agencies TRBO and NXDN that are not interoperable with anyone else in their regions.

And a lot of agencies are making bad decisions on the recommendations of their internal "experts".

Cheers!

As always.

 

[SCPD]

Based on??

I'm not aware of any free upgrade deals from DVSI.

BTW, someone should implement this DVSI Patent some weekend in VB or Perl. Could be fun.

 

[N_Jay]

I'm not aware of any free upgrade deals from DVSI.

Are you aware of any of the terms?

 

[radiofan1]

P25 phase II will be TDMA. Look at the docs.

Because motorola says so. :roll:

 

[N_Jay]

Because motorola says so. :roll:

No, because TIA-TR8 says so.:roll::roll:

 

[greenthumb]

No, because TIA-TR8 says so.:roll::roll:

Correct

 

[N_Jay]

Correct

The depth of the misinformation out there always amazes me.

I can understand people not knowing, but the so many people have such strong beliefs in stuff that is just plain incorrect.

 

[radiofan1]

No, because TIA-TR8 says so.:roll::roll:

Yes. Because motorola said so.

 

[N_Jay]

Yes. Because motorola said so.

Were you there?

Have you ever been to a TIA meeting? Any standards meeting?

Or are you just one of those "Know-it-alls" we keep hearing about?

 

[greenthumb]

Yes. Because motorola said so.

Let's explore this a bit so I can have a better understanding for your source of this information. I have two questions:

What makes you believe that Motorola said or dictated that Phase II is TDMA, and that this differs from what the EIA/TIA standards documents describe?

According to your understanding of the standards documents, what is P25 phase II if it is not a technological change to TDMA, and what EIA/TIA standards document supports this?

 

[radiofan1]

Of the major manufacturers, who besides motorola supports tdma?

 

[N_Jay]

Of the major manufacturers, who besides motorola supports tdma?

All! (Since TIA Standards are developed through consensus)

And I believe that M/A-COM (now Harris) and EADS also submitted TDMA proposals for consideration. (Other may have also).

The resulting standard contains harmonized concepts from all three proposals, and other inputs.

 

[SCPD]

Are you aware of any of the terms?

Yes. One of the terms was "Shhh. Don't tell N_Jay!".

 

[appalachianscanner]

7k30f1e

Is 7K30F1E P25? I havnt heard of 7.30 kHz spacing, 7.5 but 7.3?

License Example: http://wireless2.fcc.gov/UlsApp/Uls...freqType=null&licKey=3146023&keyFreq=25528135

 

[N_Jay]

Is 7K30F1E P25? I havnt heard of 7.30 kHz spacing, 7.5 but 7.3?

License Example: ULS License - Conventional Public Safety 700 MHz License - WQLA464 - CITY OF JOHNSON CITY, TN - Frequency 000770.35625000

Occupied bandwidth and channel spacing are not the same thing.:roll::roll:

 

[appalachianscanner]

Re:

You know what I meant..

Is 7.3 kHz of "occupied bandwidth" atypical of P25? They just granted the license yesterday and im wondering if it could be anything other than P25.
I take the short answer is yes, because the designator doesn’t tell the technology just the emission characteristics.... so.... would this designator be "common" for anything else?

Im thinking some fat phase II, skinny narrowband... or a typo