New DART Radio System

[mwjones]

Back from another day of testing my new mobile rig, and I believe the DART puzzle is complete as far as the sites go.

89.89 is DFW Airport, not a high power site like the two simulcast sites, I could barely pick it up 1 1/4 miles away, leading me to believe that it is aimed for coverage when the trains are somewhat below grade coming into the North Side of the airport.

Here's what DSDPlus decoded:

Site: 89.89 NAC=059 ; DFW Airport

Neighbor: 46F74.0D6-60.60 ; North Simulcast
Neighbor: 46F74.0D6-78.78 ; Downtown-South Simulcast
Neighbor: 46F74.0D6-93.93 ; Subway Tunnel

Channel 0-404: 856.06250 SCC
Channel 0-432: 856.41250 CC
Channel 0-562: 858.03750 SCC
Channel 0-702: 859.78750 SCC

Now, on to 93.93 - as I guessed in the earlier post, this is a "leaky coax" system for coverage in the Subway Tunnel between Downtown and Mockingbird Lane. I locked the tuner on the known control channel in the neighbor list and drove past the mouth of the tunnel Downtown. Was able to receive just enough to decode the site (a relief since the other option would have been to condense the mobile rig down to a portfolio or backpack size that I would have to take on the train through the tunnel while it covertly logs away)

Site: 93.93 NAC=05D ; Subway Tunnel

Neighbor: 46F74.0D6-60.60 ; North Simulcast
Neighbor: 46F74.0D6-78.78 ; Downtown-South Simulcast
Neighbor: 46F74.0D6-89.89 ; DFW Airport

Channel 0-404: 856.06250 SCC
Channel 0-432: 856.41250 SCC
Channel 0-702: 859.78750 CC

I also went out to Hurst, and while I was well within range of the antenna mast, no control channel was found, so that may still be a work in progress, or they are delaying it until a future date.

 

[mwjones]

For those keeping score, the data collected so far has been submitted to RRDB, and is now awaiting one of the fine DB Admins to do their magic.

 

[Russell]

Staged at Dallas Area Rapid Transit P25 Trunking System, Dallas, Texas. I have some work to do.

 

[mwjones]

Work gave me the last 3 days in the SRT-121/I-35E area for all day meetings, so I took the mobile rig and a "solar generator" to keep it going and set on the 3rd floor of our parking garage, letting it monitor the DART Northside Simulcast site at Carrollton.

As I type this, I see someone else submitted some talkgroups that align with my findings, so I probably won't be submitting anything else yet.

It appears the system is still in testing, as on Tuesday I picked up voice comms on Talkgroup 1026, which sounded like a bus dispatcher talking to buses and bus mechanics but no other talkgroups. Audio quality is understandable but still some distortion (like they're still dialing it in)

Wednesday brought Talkgroup 1022 but no 1026, and I recorded several audio files, but there was no audio on any of them.

Thursday brought Talkgroup 1021, but neither of the previously logged ones, and like 1022, there was no audio recorded (a pop started each transmission, but no voice).

Lots of other talkgroups lit up with affiliations, but no communications. The system also appears to be one of the newer Harris systems that sends radio "names" along with their numeric ID's OTA.

TLDR Facts:
Talkgroups logged:

• 1020-1022, 1026
• 2101, 2113-2114
• 4221-4225, 4228, 4236
• 9904
• 11056-11066 (The 11xxx talkgroups appear to be patches between 2101 and 2113 based on the setup and teardown messages, and may not be standalone talkgroups)
• 11074-11078
• 11083, 11085

Radios:

• Most Buses have 5-digit radio ID's, and they use a name of "BUS" followed by a 5-digit number (presumably the number of the bus)
• The mechanics also are using 5-digit radio ID's, and have the name "SPR-" and a 4-digit number (again presumably the vehicle number)
• Dispatchers are using 7-digit radio ID, and have just a 5-digit number for the radio name.
• There are also radios with the name "NRV-" and a 4-digit number with a 7-digit radio ID, my guess is that is something referring to the light rail vehicles.
• There are other radios using 7-digit numbers starting with 727, which is presumably the DART Police, where names were sent OTA they came up as "BCC", sometimes followed by a number.
• Several radio calls were logged as "External", but I don't know if that is patches from the OpenSky system or otherwise (although my guess is everything is being patched from the OpenSky while in testing.

One final note, all communications were logged as Phase 2 TDMA, and no sign of Phase 1 CDMA.

 

[kmartin]

So I see that TGs are posted for Dart police , are these in the clear ?

 

[andy51edge]

TGs 4201 and 4202 are quite busy with DART Police and Security traffic. It seems 4201 is the patrol north of the Trinity River excluding Downtown Dallas and 4202 seems to be south of the Trinity River plus Downtown Dallas. Does that division sound correct to the rest of the group?

 

[BenScan]

TGs 4201 and 4202 are quite busy with DART Police and Security traffic. It seems 4201 is the patrol north of the Trinity River excluding Downtown Dallas and 4202 seems to be south of the Trinity River plus Downtown Dallas. Does that division sound correct to the rest of the group?

As best as I can tell so far, yes.

 

[BenScan]

Looks like more sites were added. I believe site 5F(95) is in Hurst.

 

[BenScan]

 

[mwjones]

Finally got around to poking around @BenScan's findings...

Site 50 shows a control channel of 857.3875 - That frequency comes back as DFW Airport's Simulcast site, no license for DART. When you connected to 95, the neighbor list shows the control channel for 50 is 851.0125 (default base), so something's not right there yet.

Site 70 shows a control channel of 859.9125 - That shows wideband licenses for the Hospital District, but again no license for DART.

Site 87 has 856.3875, another wideband license for the Hospital District but not DART.

Site 91 has 861.3125, which is licensed to James Hopper (aka Megahertz Technology), again, no DART.---

Site 95 has 855.7625, and looks to be the Hurst site, since WRVM739 also has the secondary control channels on that license.

So we've got 4 mystery sites showing as neighbors. Looking statewide, 857.3875, 859.9125 and 856.3875 are all licensed to Metropolitan Transit Authority of Harris County (aka Houston Metro).

That leaves 861.3125 - PDV Wireless (Anterix) has that frequency licensed in Galveston County (and it was only issued in February) - I suspect this is one of their licenses that will be transferred to another licensee as part of a swap for a 900MHz frequency in their wideband block.

So, could Houston Metro be pulling some of their licensed frequencies from TxWARN (all three show on the Harris County Central Simulcast site) and move to a standalone radio system linked to DART? The fact that the 5 identified sites cover most of DART's service area (including TRE to Fort Worth), I don't know where else the other sites would be.

Let the conspiracy theories begin...

 

[kmartin]

Well , here's one that's far out there ! Revival of the high speed rail system between Dallas and Houston project , killed off years ago , being looked at again ! LOL !

 

[kmartin]

Well , here's one that's far out there ! Revival of the high speed rail system between Dallas and Houston project , killed off years ago , being looked at again ! LOL !

OH ! Lookie here !

• Amtrak is currently actively involved in planning and advancing the project with recent federal funding secured to continue development.
  
  
  
  • 
    
    
    
    

 

[kmartin]

OH ! Lookie here !

• Amtrak is currently actively involved in planning and advancing the project with recent federal funding secured to continue development.
  
  
  • 
    
    
    

But this topic can be talked about later on another discussion

 

[BenScan]

Some 700Mhz has been added to the system.

 

[mwjones]

Some 700Mhz has been added to the system.

View attachment 172532

Looks like most of those are the 700MHz frequencies they had on the (Not-so) OpenSky system. All of them are licensed to DART on WQLF480 at all of the same sites.

 

[mwjones]

Poked around a few of the DART sites today, and things are starting to come a little clearer, based on my presumptions and discovery, it's looking like this:

Site 50.50: North Simulcast 700MHz (Confirmed at Garland and Plano)
Site 60.60: North Simulcast 800MHz
Site 70.70: South Simulcast 700MHz (Confirmed at UNT-Dallas and Downtown)
Site 78.78: South Simulcast 800MHz
Site 87.87: DFW Airport 700MHz (need confirmation)
Site 89.89: DFW Airport 800MHz
Site 91.91: Mockingbird Tunnel 700MHz (confirmed near downtown portal)
Site 93.93: Mockingbird Tunnel 800MHz
Site 95.95: Hurst

I did pick up DART PD on the 700MHz sites, but also saw some bus radios try to affiliate with (but get denied) on the sites. My guess is that DART PD will be on both bands, while bus operations will be on 800MHz and rail operations on 700MHz (and since I also picked up the OpenSky signals, my guess it that rail has not transitioned yet.

 

[BenScan]

Poked around a few of the DART sites today, and things are starting to come a little clearer, based on my presumptions and discovery, it's looking like this:

Site 50.50: North Simulcast 700MHz (Confirmed at Garland and Plano)
Site 60.60: North Simulcast 800MHz
Site 70.70: South Simulcast 700MHz (Confirmed at UNT-Dallas and Downtown)
Site 78.78: South Simulcast 800MHz
Site 87.87: DFW Airport 700MHz (need confirmation)
Site 89.89: DFW Airport 800MHz
Site 91.91: Mockingbird Tunnel 700MHz (confirmed near downtown portal)
Site 93.93: Mockingbird Tunnel 800MHz
Site 95.95: Hurst

I did pick up DART PD on the 700MHz sites, but also saw some bus radios try to affiliate with (but get denied) on the sites. My guess is that DART PD will be on both bands, while bus operations will be on 800MHz and rail operations on 700MHz (and since I also picked up the OpenSky signals, my guess it that rail has not transitioned yet.

I'm thinking the 700Mhz ones might be their replacement for the previous P25 interoperability system.

 

[mwjones]

I'm thinking the 700Mhz ones might be their replacement for the previous P25 interoperability system.

Could be any number of options - I was just thinking that I know Harris has the ability to convert OpenSky radios to P25 (They long had this capability, as they did the same with EDACS to ProVoice and EDACS to OpenSky - Continental Airlines in Houston bought new radios as part of their OpenSky project, but the radios were installed/issued in EDACS compatibility mode, and then an update was made to flip them to OpenSky), so the current radios that are in the Light Rail Vehicles may be getting that conversion, because I don't know how easy it is to replace the radios in the rail cars.

I just don't see the need for such a robust build out just for an interoperability layer, especially with the system as a whole being interoperable.

 

[BenScan]

I couldn't get any hits on the 774.15625 at D/FW just now.

 

[mwjones]

I couldn't get any hits on the 774.15625 at D/FW just now.

I know when I found the 800MHz I had to be within a mile of the DART station at the North End - I was setting at Founders Plaza and it was at the very fringe, but if I went down the service roads towards Terminals A and B it got stronger the closer I got.

Looking at Street View, it looks like they're using Yagi's for the antennas, which would make them very directional towards the terminals.

And it could be that they haven't finished setting up that site yet - with only 3 frequencies, they might not switch it until they're close to switching the Rail Cars over, leaving the OpenSky running.



I'll try to shoot down there over the weekend, schedule permitting and see if I can pick up anything.