GATRRS Phase I or II?

[rattlerbb01]

He's not saying it is a Phase 2 control channel, just that the datastream he is getting from the control channel is reporting that the site is Phase 2 capable. The 5th table on the bandplan also shows that the 762 band has two slots for that section, indicating that TDMA could be used by a capable radio.

 

[Russell]

Correct. The Phase II indicator is that the controller is Phase II capable. The system system could still have 100% Phase I mobiles and the Control Channel advertise Phase II. RR Policy is to post what the CC is advertising whether there is any Phase II radio traffic or not. Most Motorola P25 systems advertise Phase II capable.

 

[jhooten]

Update:
Went through and cleaned up the programming. I'm getting clean decodes now on everything but the 74xx talkgroups the list says belong to TXDOT.

Thanks for all the replies.

 

[rn1nduk1]

unknown variable. My only best guess is whatever tower listening to, may be phase ii capable and radios on the tower programmed to allow for phase ii. i think that model you listed was only phase 1. So what may be occurring is you missing some of the TXDOT because radios are programmed for phase ii and the controller on site is phase ii capable. Rest you hear may be only phase 1 capable radios and hear all of it (the backwards compatibility). A phase ii is going to either take the single frequency and more or less, use bottom half of that frequency, top half of that frequency, meaning spectrum bandwidth, or entire bandwidth of the frequency. Just depends how the Time-division multiple access (TDMA). is used. So in effect, a single frequency can be used at same time, and use time slot 1 or time slot 2. Is how the sites with few frequencies can in effect double the capacity of the site of simultaneous talkgroups.

 

[jhooten]

unknown variable. My only best guess is whatever tower listening to, may be phase ii capable and radios on the tower programmed to allow for phase ii. i think that model you listed was only phase 1. So what may be occurring is you missing some of the TXDOT because radios are programmed for phase ii and the controller on site is phase ii capable. Rest you hear may be only phase 1 capable radios and hear all of it (the backwards compatibility). A phase ii is going to either take the single frequency and more or less, use bottom half of that frequency, top half of that frequency, meaning spectrum bandwidth, or entire bandwidth of the frequency. Just depends how the Time-division multiple access (TDMA). is used. So in effect, a single frequency can be used at same time, and use time slot 1 or time slot 2. Is how the sites with few frequencies can in effect double the capacity of the site of simultaneous talkgroups.

Bastrop

 

[rbarker]

I'm very confused by the postings. I'm in Austin and I am confused by this Phase 1 Phase 2 stuff. I can hear the GATRRS system just fine including Bastrop using a Pro96 and GRS PSR-500 and Uniden 436HP and HomePatrol 1 and BCD396XT. talkgroups in the 74xx range are usually TxDot if you find new ones, please update the data base. Most of the newer scanners work off the data channel so you don't have to necessarily program anything else. I haven't run into an issue where i'm only hearing half a conversation. Some talkgroups may be encrypted where half the conversation is encrypted.

 

[jhooten]

I'm very confused by the postings. I'm in Austin and I am confused by this Phase 1 Phase 2 stuff. I can hear the GATRRS system just fine including Bastrop using a Pro96 and GRS PSR-500 and Uniden 436HP and HomePatrol 1 and BCD396XT. talkgroups in the 74xx range are usually TxDot if you find new ones, please update the data base. Most of the newer scanners work off the data channel so you don't have to necessarily program anything else. I haven't run into an issue where i'm only hearing half a conversation. Some talkgroups may be encrypted where half the conversation is encrypted.

The two main ones I notice are 7414 and 7425. They give the echoing dripping water sound instead of a clear decode.

 

[rn1nduk1]

The two main ones I notice are 7414 and 7425. They give the echoing dripping water sound instead of a clear decode.

I do not really know. Hopefully to clear up confusion, I have not seen a talkgroup in the Odessa 700 site use a time slot in phase ii. So the 700 machine here as of now is being used in phase I modulation. The bandplan change when it went online shows 2 slots for the added 700. Theoretically, if they tried to use the 700 machine as phase ii, then the sister sites wouldn’t simulcast the audio because the 800 sites that it sisters with, and vhf sites sisters to those are still phase I controllers to best of knowledge, and bandplan for 13e still shows the 800 and vhf to be phase I. (1 slot).

 

[rn1nduk1]

Should add. Since it has sister sites, my thought would be that no radio that is connected to the 700 machine is programmed for that system as TDMA capable so that it uses phase 2 My thought would be at that point then the 700 site would mostly be site trunking only. But I don’t know how they program those systems either. Could they set talkgroups to only simulcast certain sites and a talkgroup only be available on the 700 machine and not simulcast? That is a programmer question for a Motorola tech.

 

[rn1nduk1]

The difference between FDMA and TDMA | Tait Radio Academy

An RF channel occupies a certain amount of radio spectrum. What is the most efficient use of this small chunk of radio spectrum that makes up our channel? There are two different techniques. The first technique is called frequency division multiple access (FDMA). This method separates channels...

www.taitradioacademy.com

simple explanation between phase 1 (fdma) and phase ii (TDMA).

 

[rbarker]

74xx on GATRRS should prob be TxDot. it's not a dripping water Sound. Are you in Bastrop or Odessa? are you not hearing anything else? I have never heard of TxDot refer to a channel number so they could come up on any of the talkgroups. I guess we can add 7425 as TxDot.

 

[rn1nduk1]

The two main ones I notice are 7414 and 7425. They give the echoing dripping water sound instead of a clear decode.

Echo sound seems more like an open mic with another radio close to the open mic.

 

[KTR722]

at least one of the 74xx TGIDs is encrypted (7414); most of the rest are in the clear.

 

[jhooten]

at least one of the 74xx TGIDs is encrypted (7414); most of the rest are in the clear.

And there you have it. It was my suspicion but that begged the question of all the talk groups on the system why would a TXDOT talk group be the only one using encryption?

Echo sound seems more like an open mic with another radio close to the open mic.

Nope, different sound altogether.