GRE and TDMA

[KK4HG]

I posted a ticket with GRE yesterday about TDMA and awoke to some bad news. John at GRE says that their current DSP firmware and such will not handle TDMA. Therefore, as P25 Phase II continues to unfold like it is around the DC area (Prince George's County, MD, Loudon County and Fairfax County, VA) we listeners will be SOL.

 

[SCPD]

or could mean NEW line of scanners????

 

[WayneH]

Same story different day in the scanner world. Communications technology is progressing a lot faster than it did in the past.

 

[rdale]

I posted a ticket with GRE yesterday about TDMA and awoke to some bad news. John at GRE says that their current DSP firmware and such will not handle TDMA. Therefore, as P25 Phase II continues to unfold like it is around the DC area (Prince George's County, MD, Loudon County and Fairfax County, VA) we listeners will be SOL.

What happens when you tune those in? Does it catch the CC still? Audio at all or just garbled?

But re-reading, we knew that all along. It doesn't appear GRE said that a future upgrade of the firmware won't handle TDMA unless I'm missing something? It says the current firmware does not, and that was a given.

 

[greenthumb]

It's the "and such" part that makes me believe that it will need to be a whole new hardware platform. Aren't all of these radios using the IMBE vocoder? I believe (correct me if I am wrong here) that Phase II will require AMBE.

 

[WayneH]

As with other more simpler DSP add requests (like conv P25 radio IDs) the memory is just not there for it.

 

[N_Jay]

It's the "and such" part that makes me believe that it will need to be a whole new hardware platform. Aren't all of these radios using the IMBE vocoder? I believe (correct me if I am wrong here) that Phase II will require AMBE.

In the case of the Motorola TDMA, the differences would be with the vocoder and some additional processing, since Both Motorola TDMA and Phase 1 both use the same modulation.

For true Phase 2, it will require a DSP based receiver since the modulation is changing to a much more linear form. (Not C4FM/CQPSK)

 

[KK4HG]

What happens when you tune those in? Does it catch the CC still? Audio at all or just garbled?

I understand second hand that yes, the CCs are catchable but I have no personal experience to back that up. A local reflector had a message on it tonight mentioning this ability. I will see if I can dig it up and copy/paste it here for you...

 

[RayAir]

Same story different day in the scanner world. Communications technology is progressing a lot faster than it did in the past.

You hit the nail on the head there. And even if scanner manufacturers could keep up, it most likely wouldn't be cost effective to even make the scanner (too small of a market).

Not to even mention proprietary systems,etc.

The newer communications technologies are not scanner friendly anyway. Even if you had the means to demodulate some of these newer digital systems you would still have to know time slots or color codes as with TRBO.,etc.

 

[troymail]

I understand second hand that yes, the CCs are catchable but I have no personal experience to back that up. A local reflector had a message on it tonight mentioning this ability. I will see if I can dig it up and copy/paste it here for you...

I've been tracking the PG system control channel and system activity using my PSR500 and Pro96Com (Pro96Com - Control channel decoder for P25 Trunked Radio Systems). It's pretty active but of course you can't hear any voice.