Golden Gate Bridge TRS...

[kg6nlw]

Has anyone had any luck in actually HEARING traffic on the Golden Gate Bridge & Highway Transportation District Radio System? I'm in Sonoma County and can see a signal on the Sonoma Mountain CC but no audio. I'm using a BCD536HP. I know they talk, it just seems super quiet! I'm in Talkgroup Scan so I can pick up all the TG's on the system.

Are they using "Link Layer Authentication" or commonly known as P25 Authentication? That might keep the scanner from hearing the traffic?

Regards,

-Frank C.

 

[Redoak]

I can hear the decoded audio traffic on 773.70625 which shows up as P25 and ‘link’ on my 396xt display. Just have the single channel programmed through. Strong signal I believe from sonoma mountain.

 

[kg6nlw]

Thanks. Sitting at Kaiser Santa Rosa I don't hear the system for some reason, even though I'm across from their yard with a nice view of Sonoma Mountain...

Regards,

-Frank C.

 

[ndalporto]

The Link Layer Authentication/P25 radio authentication is an access technique that consists of an information exchange between the subscriber unit and the affiliating site to confirm the radio is authorized to affiliate to the system. This prevents unauthorized subscribers from affiliating to a site by blocking the registration if the authentication fails. This has no effect on using a scanner.

Link Layer Encryption (LLE) is a planned addition to the P25 standard that will enable the encryption of control channels, IDs, etc. When this is implemented it would prohibit using a scanner to follow traffic on the system, even if the system talkgroups are unencrypted. This is all in the works, and there's no site equipment or subscriber units that support LLE, as it hasn't been added to the standard yet.

 

[officer_415]

I suspect there's just not much traffic carried on the Sonoma Mountain site. There's a fair amount of the traffic on the main simulcast (GGB toll plaza, Mt. Tam, Big Rock Ridge, and Bald Peak in the east bay), but it's mostly GGB patrol and maintenance. There is also traffic on the bus voice talkgroups, but even those probably wouldn't go out over Sonoma Mountain unless the bus was at the northern end of their route.

 

[ndalporto]

Yes, it's worth noting that the traffic will only be carried on the site if a radio is affiliated to that specific site with the talkgroup you're wanting to listen to selected. Otherwise, you'll hear nothing. The fundamental concept of a Trunking Radio System is that talkgroup traffic is only transmitted on a specific site when required.

 

[Redoak]

franks_ham
I recently got an SDS100 and programmed the GGB TRS system but wasn't receiving anything when my 396XT would on 773.70625. Found out I had the Service Types turned off for Security and Transportation. After enabling I can now hear them on the SDS100. I believe the BCD536HP also has similar Service Types so you might check that those are on. The RR database shows the Service Types for this system as Security, Public Works, Multi-Tac and Transportation. Still not much traffic though as others have commented unless they are up North near Sonoma Mountain.

 

[kg6nlw]

I suspect there's just not much traffic carried on the Sonoma Mountain site. There's a fair amount of the traffic on the main simulcast (GGB toll plaza, Mt. Tam, Big Rock Ridge, and Bald Peak in the east bay), but it's mostly GGB patrol and maintenance. There is also traffic on the bus voice talkgroups, but even those probably wouldn't go out over Sonoma Mountain unless the bus was at the northern end of their route.

The Route 101 goes to D3 quite often...I'd think the Sonoma Mountain site would be pretty active there for the time the 101 shows up this way.

Regards,

-Frank C.

 

[officer_415]

Yeah the buses don't talk much anyway.

 

[kg6nlw]

Thanks. Guess I'll have to come further South to listen to something!

Regards,

-Frank C.