While investigating a relatively new type of digital trunked radio system called Icom iDAS
, I made a most unexpected discovery!
The system I was looking at is called the Signature Wireless Group iDAS MultiTrunk system:
Signature Wireless Group iDAS Multitrunk (Bay Area) Trunking System, San Rafael, California - Scanner Frequencies
It's been online for at least a year, and I used to hear the NXDN4800 voice data on it (sample here
), but DSD would never decode it. Just in time for Christmas however, a new DSD build called DSD Plus was posted in the Digital Signals Decoding forum two days ago, and it decodes trunked NXDN4800 (iDAS) successfully! (Provided you have a discriminator tapped scanner.) Most of the iDAS frequencies are easily recognizable because they have a digital idle-burst every 4-5 seconds when not in use.
Listening to the Signature Wireless iDAS Multitrunk system I have only identified one user so far (there are a couple), and I was very surprised to discover it was the dispatch channel for Medic Ambulance
in Solano County!
Their dispatcher identifies as "Vallejo", they use 10-codes quite extensively, and their dispatch channel covers both code 2 BLS transports as well as code 3 ALS responses. Hospitals heard include Kaiser in Vallejo and Vacaville, and Sutter-Davis. Unit IDs use a three digit format, and units heard included "300", "305", "308", "808", etc. Given all the above, and after hearing code 3 ALS responses in Vallejo and Fairfield I think it's safe to say it was definitely Medic Ambulance I was hearing.
Here is a press release from SWG on the iDAS Multitrunk system. Note it is planned to be a 30 site network, although I'm not sure if all those sites are operational (many still contain current SWG LTR sites):
Unfortunately the current version of DSD Plus doesn't display talkgroup ID, radio ID, system ID or site number for NXDN, so that information is unavailable as of yet. I suspect it will become available in the near future which is why I went ahead and created the system in the db. I am pretty certain of the frequencies for the Big Rock, San Pedro Ridge and Grizzly Peak sites... however the licenses are much more inconclusive for the other two.
(unlisted, licensed only to PG&E in ULS) and 462.1375
appear to be part of the same system. 462.1375 comes back to (WQJE250 (Signature Wireless Group Inc) FCC Callsign Details
) Wolfback Ridge, which is a low altitude site in Sausalito, CA. The propagation is much too weak to be coming from Big Rock Ridge.
is extremely weak from the north bay, and licensed to (WPKY880 (Signature Wireless Group) FCC Callsign Details
) with locations at both Mt Diablo and Black Hills. I recall their old Black Hills LTR system being about this weak so I suspect that's it (seems much too weak for Diablo), but if anyone in the east bay could confirm that would be helpful.
is another confirmed weak frequency, but so far I can only find an old mobile license for it (WPLU660 (TADLOCK AND ASSOCIATES) FCC Callsign Details
). Any leads on this one, and any other new NXDN frequencies belonging to this wide area system would be appreciated.
Note that SWG uses multiple names on their licenses, including "Signature Wireless Group", "Griffin Wireless Group" and "Tadlock and Associates", which makes things a bit harder to find.
Hope this helps if anyone was curious about EMS dispatch in Solano county!