Batboard

Does anyone know if the XTS line will be Phase 2 capable?

No, it will not be. The intention all along was that it would be, and Motorola was confident in that, since they in large part drive the ongoing defining of the P25 P1/P2 standards. However, the APCO25 group decided to go with a 12.5Kbs standard for Phase 2, as opposed to Motorola's proposed 9.6Kbs...which rendered the entire XTS/XTL hardware platform incapable of Phase 2 operation. The APX line is currently the only 'Phase 2 ready' offering from Motorola.

This is how I understand it in a nutshell. I'm sure others with much more insight & knowledge of these things (cough...wowbagger...cough) will correct me if I'm wrong.

Lawman7346 wrote:Does anyone know if the XTS line will be Phase 2 capable?

Short Answer: No.

-Alex

Not that it matters much. Here in Nevada, we are just barely getting people in the rural departments to understand PL....

lets keep changing the digital coding so that we can plan obsolescence and tell you that you $4000 wont work now so you will have to buy a $7000 radio.

that is how we make the $$$$$$$$.

wavetar wrote:I'm sure others with much more insight & knowledge of these things (cough...wowbagger...cough) will correct me if I'm wrong.

Only it it wouldn't violate any of the NDA's I am under...

Besides, I am busy on another project (actually, another 6 projects, across 12 time zones, 6 locations, and about 50 engineers).

I'd be willing to take a bet that its probably a marketing decision rather than a technical one (ie, the ASTRO25 platform can do phase 2 12.5kb/sec with firmware updates) but /\/\otorola have chosen not to, so that forces customers to spend more $$$ on the APX line.

All the demodulator/coder stuff in the ASTRO and ASTRO25's are software defined in the DSP - so it's all software defined and very easy to change with firmware uplifts.

MattSR wrote:I'd be willing to take a bet that its probably a marketing decision rather than a technical one (ie, the ASTRO25 platform can do phase 2 12.5kb/sec with firmware updates) but /\/\otorola have chosen not to, so that forces customers to spend more $$$ on the APX line.

All the demodulator/coder stuff in the ASTRO and ASTRO25's are software defined in the DSP - so it's all software defined and very easy to change with firmware uplifts.

I would have to agree. It would take one heck of a technical explanation why it would not work. And I haven't heard one yet...

I could see that perhaps the circuitry used on the RF board isn't capable of operating in Phase 2 mode.

This said, I would imagine Mother M could come out eith a redesigned RF board for the 5k which would support it. Then again, there is a large PS system up here who has dumped a lot of coin into the 5k, and have since shifted to purchasing APX radios. Maybe just to get the newesr, or perhaps there are other plans down the road to swtch to Phase 2.

same with our current Moto Astro 25 statewide system...a whole lot a 5Ks on it but now if you join up you need to go with an APX. Interesting to see what happens if and when the system goes Phase II...

Batwings21 wrote:I would have to agree. It would take one heck of a technical explanation why it would not work. And I haven't heard one yet...

OK, let me offer one. Now, bear in mind this is NOT me talking from actual knowledge of how Motorola implemented their radios, but just from my general knowledge of radio design and P25.

There are 2 basic ways you can build a radio that can do Phase 1 P25 (and Motorola's F2, btw, as it uses the same modulation scheme).

The first way is you do things old school: RF to IF to FM detector to baseband, then digitize the baseband, sync and slice. This is nice and simple, as you really only need to sample about 4x the baud rate (19200 kSamples/second, remember that P25 is 4800 baud). That's nice and slow, and doesn't take much horsepower - I'd suspect just about any microcontroller made in the last 5 years could do that.

The second way is to do it the modern way: RF to IF, then digitize the IF and do the rest digitally. Depending upon what your final analog IF bandwidth is, you are looking at between 96kSamples/second to 192kSamples/second (or higher - the 2975 does 20Msamples/sec). That takes a bit more meat to process, but really modern microprocessors like the OMAP can do that with no problem.

Now, IF the older radios are done the first way, and IF they are running a hardware fixed sampling rate that is a multiple of 4800 baud but not a multiple of 12.5kbaud, then making them decode the new stuff would be a beyatch - even more so if the signal processing is being done on a wimpy CPU.

Now, is that how the XTS5000 is done? I don't know - I have no knowledge of that, I didn't work on the autocal routines for that radio, I KNOW NOTHING! NOTHING! about how Motorola does their radios (and if I did it would be under NDA and I wouldn't be making a post like this).

Hey wowbagger are you one of the group of Aeroflex Engineers who are coming out to Arizona this week to show off the 3920 ?


Mike

mike m wrote:Hey wowbagger are you one of the group of Aeroflex Engineers who are coming out to Arizona this week to show off the 3920 ?


Mike

No, I'm way too busy to be allowed to leave. As you might guess, I'm designing the next gen....

Yep I heard some talk about a new one coming out, I'd sure like to have a chance to play with a prototype when it's available.

M

will it be possible to scan p25 phase 2 systems using a motorola radio? think scanner manufacturers will come out with a phase 2 scanner or are we heading toward unmonitorable systems?

Batman wrote:will it be possible to scan p25 phase 2 systems using a motorola radio?

Not unless you want a very expensive brick in the shape of an APX.

Batman wrote:think scanner manufacturers will come out with a phase 2 scanner or are we heading toward unmonitorable systems?

That's really up to them, but if Motorola can build a TDMA Phase 2 receiver in their radios, then I would suspect that the scanner manufacturers can too.

Hightower wrote:Brick? Are you talking about an APX getting inhibited? That sure ain't a brick when it gets inhibited. The radio is just in a "shut down state" that can easly be re-enabled by dispatch - hardly a brick.

"Excuse me Mr. System Administrator? I hate to bother you, but I bought a nice shiny APX radio for an order of magnitude more than the average cost of a scanner, and I put it on your system so I could listen in. Seems you have a problem with that, and now my very expensive radio is, at least for the moment, a very expensive non-functional object similar to common building construction material. Could I trouble you to un-inhibit my radio?"

Hightower wrote: Why doesn't someone research the DSP IC used in the Astro platform and Astro25 platform. That will reveal if Moto is blowing smoke up our a$$ saying Astro/Astro25 radios are incapable of phase2 operation.

Moto will tell customers Astro Sabers and XTS3000 are not capable of 800mhz P25 (4800), but we all know different.

They are blowing smoke up everyone's asses.

The answer lies in the ASTRO Saber/XTS3000 service manuals. Put simply, even first generation ASTROs use a chip called the DSP56000, which does complex baseband sampling (aka I/Q or more recently, software defined radio such as wowbagger alluded to in the second scenario in his previous post)

The DSP56000 has more recently been used in ADSL modems with similar QPSK style modulation at throughput rates in the order of tens of megabits - the 12khz or so rate of Phase 2 is a cinch in comparison even after you take into account signal rates and FIR filters etc etc..