New VHF digital system 143 MHz?

[jimvm]

I discovered more VHF digital traffic today.
Signal levels are around -120 dBm vs -105 dBm for Beale AFB.
Working on these frequencies so far.

143.6125
143.3875
143.2125
143.3125
143.3625

From Olivehurst, CA

jim vm

 

[kma371]

Any NACs?


Sent from my iPhone 4 using Tapatalk

 

[jimvm]

Nac?

Using a BCD996T so no NAC capabilities and no decoding of audio so far.
Looking for a control channel also.
Found a new frequency 143.1875.

I was scanning from 137.000 to 144.000 MHz, step 12.5 kHz using my Optocom with
Probe software. Found these new frequencies and noted their signal strength is less
than the Beale system. I did punch in a few frequencies in the BCD996T and listened for
any audio. Not sure of the digital format but it sounds in analog like P25 repeated xmsns.

My guess is it's a new Travis system or some military stuff from Mt. Diablo.

Will keep trying to figure out, mornings are a good time for activity.

jim vm , Sacto. vly

 

[jimvm]

To KMA371

You know I am probably copying the base units on the input frequencies.
That would explain why there are 6 frequencies logged so far!
One other frequency would be the control channel input, that adds up to 7 channels, input.

Never mind !!!

Is there a way to determine the input frequencies using the base 138.000, step 12.5 and offset 380?
Yeah, there we go!

jim vm

 

[gmclam]

Placer county is setting up a VHF trunked radio system. I wonder if you are getting input frequencies related to that. Otherwise, considering the band, something at Beale AFB?

 

[jimvm]

It is the Beale system input frequencies

I verified by monitoring the VHF Beale system and timed the input transmissions with simultaneous
trunked outputs.

I am hearing the base radios talking since they are stronger than the portables.

12.5 kHz spacing is NFM, 25 kHz spacing is AM.

Like I said, never mind!

73 jim vm

 

[SimpleSkye]

Were you able to match what input went with what output? Curious if I can hear the mobiles up here in the sticks...

 

[jimvm]

Input frequencies listing for Beale VHF system

I was not ignoring you SimpleSkye, it just took me a little time to find that
last input channel. I do not know if there is a one to one mapping of inputs
to outputs or if they are dynamic assigned. Most likely they are in frequency
order. Maybe someone with more knowledge of Motorola trunking systems
can fill in. Here are the 7 input frequencies I have copied.

143.1875
143.2125
143.2625
143.3125
143.3625
143.3875
143.6125

Good luck trying to hear them.

jim vm

 

[WayneH]

I was not ignoring you SimpleSkye, it just took me a little time to find that
last input channel. I do not know if there is a one to one mapping of inputs
to outputs or if they are dynamic assigned. Most likely they are in frequency
order. Maybe someone with more knowledge of Motorola trunking systems
can fill in.

They are probably in sequential order and would line up with the outputs in sequential order. Someone would need to run software that decodes the control channel to figure out the pairing. Unfortunately since I'm so far aware the sig fluctuates so much I usually miss it to try and match the pairs, which is easy with TREPORT.