Caltrans DMR Surprise?

[kg6nlw]

Maybe someone knows, maybe someone can investigate more. In Sonoma County, I can clearly hear what seems to be a DMR signal on a CalTrans channel but DSD+ isn't decoding it. Does anyone have an idea as to what exactly I'm hearing?

858.7625 which is licensed to the following parts of CalTrans
Statewide Channel P
District 1: Lakeport, Legget v2, Point Arena, Orleans Maintenance.
District 2, 5 and 10: LOTS of areas but none I'd hear
District 4: Devil Slide and Pigeon Point

Regards,

-Frank C.

 

[scannerboy02]

Is it a continuous signal like a control channel or intermittent?

Do you have the latest version of DSD+ Fastlane?

Are you able to post a recording of the signal?

Could it possibly be coming from Big Rock? That is the only location I could find that's licensed for digital emissions.

ULS License - PubSafty/SpecEmer/PubSaftyNtlPlan,806-817/851-862MHz,Trunked License - WPBH806 - CALIFORNIA, STATE OF - Location 1

 

[scannerboy02]

I got interrupted while typing last night. I was going to add, could it possibly be one of the "new" P25 TDMA control channels? Until the last few DSD+ FL updates those were not decodable with software, the latest updates will now decode it.

Being that that frequency is licensed at Big Rock for P25 trunking that would be my best guess at this point without actually being able to hear it myself.

 

[kg6nlw]

Is it a continuous signal like a control channel or intermittent?

Do you have the latest version of DSD+ Fastlane?

Are you able to post a recording of the signal?

Could it possibly be coming from Big Rock? That is the only location I could find that's licensed for digital emissions.

ULS License - PubSafty/SpecEmer/PubSaftyNtlPlan,806-817/851-862MHz,Trunked License - WPBH806 - CALIFORNIA, STATE OF - Location 1

Yes, I have auto-updates turned on and got 2.360 the other day. I would be very surprised if it was Big Rock as *most* Marin sites are shielded from my view by English Hill and other hills in Sonoma County. I'm all the way up in Cloverdale. Let me see if I can get an audio recording together.

Regards,

-Frank C.

 

[scannerboy02]

So upon further research it does appear the state has been granted a modification to add P25 TDMA emissions to Big Rock.

ULS Application - PubSafty/SpecEmer/PubSaftyNtlPlan,806-817/851-862MHz,Trunked - 0009590652 - CALIFORNIA, STATE OF - Service Specific

They also have a pending request for San Leandro Hill.

ULS Application - PubSafty/SpecEmer/PubSaftyNtlPlan,806-817/851-862MHz,Trunked - 0009348881 - CALIFORNIA, STATE OF - Transaction Log

 

[kg6nlw]

That is interesting. Both areas are well beyond what I should be able to hear. :\

Regards,

-Frank C.

 

[kg6nlw]

I'll add this in as well, this is the waterfall in SDR# for the signal.


Regards,

-Frank C.

 

[scannerboy02]

Is anyone else within a closer proximity to Big Rock able to check for signals on 856.7625, 857.7625, 858.7625, 859.7625 and 857.0875?

It appears this is possibly a P25 control channel we just need someone with a little better reception to confirm it.

Thanks

 

[kg6nlw]

I got a blip of something. I can't tell ya what it means. 858.7625 was what I was listening to at the time...11/2/21 around 1520H.


Regards,

-Frank C.

 

[scannerboy02]

If this is a dPMR signal, and it could be, I certainly hope it's not CalTrans. Given that you have heard it on two different frequencies licensed to them is very interesting.

 

[kg6nlw]

dPMR from my understanding is basically either a "weaker un-decodable signal" or a Moto Type I/Type II that DSD+ can't decode, to begin with.

Regards,

-Frank C.

 

[scannerboy02]

Have you tried running UniTrunker on it to see if it's the analog system on Big Rock?

 

[kg6nlw]

I have not. UniTrunker and I don't always get along. I've tried multiple times to "listen" to the MERA system with UniTrunker, and despite making sure everything saves, the next time I boot it up, ALL THE INFO is gone!

I will try UT in a little bit and see what it does. Seems the signal is stronger up here as the sun sets, ya know, RF propagation and all that...

Regards,

-Frank C.

 

[kg6nlw]

UT has yet to see anything but it is now running on 858.7625...We shall see what happens.

Regards,

-Frank C.

 

[AM909]

It looks like three, very closely-spaced (~1.5kHz), very narrowly-modulated carriers; not like any DMR or P25 (or any other intelligible signal). If you want to do a baseband recording, maybe with a very narrow sampling rate (e.g. 0.25 MSPS) since that's the only sig we're interested in, and post it, we can have a better look at it. My guess is unintentional radiation of a non-communication source.

 

[kg6nlw]

It looks like three, very closely-spaced (~1.5kHz), very narrowly-modulated carriers; not like any DMR or P25 (or any other intelligible signal). If you want to do a baseband recording, maybe with a very narrow sampling rate (e.g. 0.25 MSPS) since that's the only sig we're interested in, and post it, we can have a better look at it. My guess is unintentional radiation of a non-communication source.

I have a feeling I'm just too far out from the site to clearly hear anything from the QTH...I had a glimpse of it coming NB the other day on my way home. I have my DSD+ and SDR# set to 0.25MSPS/Auto. The signal I did get @scannerboy02 couldn't get the wav file to decode because the signal was too weak.

Regards,

-Frank C.

 

[es93546]

858.7625 is also licensed to the University of California for mobile use statewide with some excepted counties, mostly in the southern half of the state, with a callsign of KB34726. I don't see this as pertinent to your reception, but I would not assume such just on the face of it. The frequency is also licensed to Merced and Riverside Counties as well as the City of Los Angeles, but none of those should be causing the reception you report. That is, unless you are picking up Merced County's repeater on the frequency at Mt. Bullion. However, the emission licensed is for analog voice and not part of a trunked system. Receiving Mt. Bullion on an 800 MHz frequency is not likely in the counties north of the Bay Area.

 

[mmckenna]

858.7625 is also licensed to the University of California for mobile use statewide with some excepted counties, mostly in the southern half of the state, with a callsign of KB34726.

It isn't UC. There have been several attempts to 'give back' that frequency over the years, but the home office just keeps renewing it.

 

[kg6nlw]

Receiving Mt. Bullion on an 800 MHz frequency is not likely in the counties north of the Bay Area.

Definitely not Mt. Bullion from Sonoma County in the Bay Area. That would be a WIDE open skip if it was!!

Regards,

-Frank C.

 

[kg6nlw]

After driving to Hawk Hill (Marin Headlands) and back via US-101, I can confirm it's something on Big Rock like @scannerboy02 thought but it isn't decoding in DSD+ FastLane. It kept showing the following from the 1R.bat command prompt.

Sync:+dPMR
Sync: no sync
Sync:+dPMR
Sync: no sync
Sync:+dPMR CRC ERR
Sync:+dPMR
Sync: no sync
Sync:+dPMR Muting non- AMBE+2 Clear Voice
Sync: no sync
Sync:+dPMR Muting non- AMBE+2 Clear Voice
Sync:+dPMR
Sync:+dPMR

Maybe @mlangeveld or someone in Marin County can set an SDR to record on just one of those 850 channels for a few days and see what comes up.

Regards,

-Frank C.