Support for TDMA P25 Phase II

[ac7xc]

Does anyone know if the new TDMA P25 systems and frequencies can be monitored and if any scanner manufacturers will be able to support it? Here in Oregon the State is installing a Statewide TDMA system over the next few years so I'm just curious if the systems can be monitored in the future.

[Chauffeur6]

Currently, no.

In the future? I guess we'll have to wait and see. Phase II is going to become very popular in short order on these P25 systems, so you can bet the scanner manufacturers will want to incorporate the capability into their digital models. How soon, or even if, that becomes reality is the obvious question.

[greenthumb]

If the current date for 700 MHz 6.25 kHz equivalent bandwidth sticks, more of these phase II TDMA systems should be showing up in the next few years on 700 MHz as users transition away from their 12.5 kHz bandwidth voice systems. Personally, unless there are substantial RF filtering improvements that don't skyrocket the price or new feature enhancements made to today's line of scanners, I won't be purchasing anything new until they add the ability to decode phase II, or put the hardware in the radio and promise a no-cost firmware upgrade to do it. I see no reason that these systems won't have the capability to be scanned since the TDMA protocol will be part of the P25 standards, thus replicable. Hopefully the scanner manufacturers will stay ahead of the technology this time instead of being several steps behind (e.g. trunking, P25 and 700 MHz).

[wlmr]

Originally Posted by greenthumb

Hopefully the scanner manufacturers will stay ahead of the technology this time instead of being several steps behind (e.g. trunking, P25 and 700 MHz).

I'm betting they may be able to work up the basic functions in the scanner but until they can test on live systems the scanner makers won't have anything ready to release right away. Anyone ever heard of the possibility of the radio system manufacturers letting the scanner manufacturers play with new stuff being developed? That would be nice but unless that ever comes into being we'll always have to wait for the scanners to catch up.

[N_Jay]

You also have to wait for a market to develop.

[wlmr]

Originally Posted by N_Jay

You also have to wait for a market to develop.

True. I'd be curious as to when/how fast that market would develop. How many people would be in the stores within a few days to a week or three of discovering that newly licensed frequencies were active with a new type of system. There seems to be persons ready to get their hands on the scanners as soon as they hit the stores - especially in the current environment of the scanner manufacturers being able to update how their product works out in the real world.

[N_Jay]

But the first Phase 2 systems won't be on the air for about a year.

[wlmr]

Originally Posted by N_Jay

But the first Phase 2 systems won't be on the air for about a year.

Makes me glad I'm not the one that's intently gazing into a crystal ball trying to figure out when to get serious about meeting the demand of a future market. Scanner buyers won't be happy with anything released later than the day after someone finds activity on a frequency. (And it needs to work flawlessly right out of the box too.)

[N_Jay]

Part of the fun of being a Product Manager.

[wlmr]

Originally Posted by N_Jay

Part of the fun of being a Product Manager.

They can keep the fun, I'll keep my hair and sanity.

[ButchGone]

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..

[wlmr]

Originally Posted by ButchGone

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..

My memory is rusty - at one point you were correct - just had to be narrower than 6.26. 2 TDMA channels per frequency was one discussion, cutting down somehow on the modulation bandwidth and staying exclusively FDMA per frequency was another.

TDMA is still out there, not just in older cellular systems. TETRA uses it I think.

I don't recall off the top of my head what LSM's modulation measures out as but at this point I think that the portable/mobile radios all talk inward using C4FM.

Anyone out there who's memory is more shiny than mine?

[greenthumb]

I don't think anyone has cracked the secret to reliable public safety grade digital voice communications using a single FDMA channel at 6.25 kHz. The big players (Motorola and Harris) are intending to sell 6.25 kHz equivalent systems to comply with the 700 MHz mandate using P25 phase II (or a close, proprietary knock off of it) which is TDMA over a 12.5 kHz channel.

If the current deadline holds, the market for these systems will grow quickly, or 700 MHz won't be used.

[Comint]

Originally Posted by wlmr

. . . TDMA is still out there, not just in older cellular systems. TETRA uses it I think.

TETRA is 4 slot TDMA in 25kHz bandwidth.
MOTOTRBO is 2 slot TDMA in 12.5kHz bandwidth
Digital Mobile Radio (DMR) Tier III, a recent European Standard, is 2 slot TDMA in 12.5kHz bandwidth.

--
Comint

[N_Jay]

There are lots of TDMA systems (and they are all significantly different)
It is neither an "OLD" nor a "NEW" technology, no more than saying "Cellular" or "trunking" is "old' or "new".


P25 Phase 2 is 2 slot TDMA.

There is a standard for 6.25 kHz FDMA but no one has yet, and no one seem eager to implement it. So if you think someone is implementing it, you are mistaken.

[nd5y]

GSM is also TDMA

[ButchGone]

Well the new 700Mhz system being installed in Tennessee uses 6.25KHz bandwidth and it's totally monitorable with a 396. I was told they are phase 2 compliant and use LSM. There are no plans to run TDMA on this. That's why I was questioning whether phase 2 had to use TDMA, thinking that TDMA COULD be used if someone wanted. I still have not found any literature showing TDMA has been mandated since other technologies work fine in 6.25KHz slots.
BG..

[Unitrunker]

The TDMA spec calls for a half-rate vocoder. The manufacturers will have to re-license the code to do this from DVSI.

[N_Jay]

Originally Posted by ButchGone

Well the new 700Mhz system being installed in Tennessee uses 6.25KHz bandwidth and it's totally monitorable with a 396.

Someone is mistaken.
It can not be since there is no such system from any manufacturer.
The fact the 396 monitors it confirms it is P25 Phase 1 (12.5 kHz, 9600 BPS, etc.)

Originally Posted by ButchGone

I was told they are phase 2 compliant and use LSM.

To quote Marty Feldman "You were told wrong."

Originally Posted by ButchGone

There are no plans to run TDMA on this.

Acording to? (Not doubting, just confused)

Originally Posted by ButchGone

That's why I was questioning whether phase 2 had to use TDMA, thinking that TDMA COULD be used if someone wanted. I still have not found any literature showing TDMA has been mandated since other technologies work fine in 6.25KHz slots.

Hence how believing a few incorrect "facts" causes you to misunderstand others.

As said;
1) P25 Phase 2 "IS" TDMA for all practical purposes.
2) P25 Phase 2 is the only 6.25e (6.25 kHz equivalent) system currently in the standards and planned for production.
3) 6.25 kHz FDMA is in the standards but not being built by anyone.

[N_Jay]

Originally Posted by Unitrunker

The TDMA spec calls for a half-rate vocoder.

True

Originally Posted by Unitrunker

The manufacturers will have to re-license the code to do this from DVSI.

Based on??