167.925 MHz & 170.750 MHz Trunked System

[ScannerSK]

All,

I came across two trunked frequencies today however have yet to determine what system they are part of. The frequencies (167.925 & 170.750) are both in the govt. band and can be decoded with the Pro-96 in FM mode.

I just located them today and have heard some conversation however nothing to identify their location yet. I cannot locate any control channels at all in the 162-174 MHz band.

My location is 40 miles north of Denver (Gilcrest, CO).

In a separate thread I'm also trying to determine what trunked systems 407.725 & 419.900 are part of and also what trunked system 415.850 & 416.000 are part of? <http://www.radioreference.com/forums/showthread.php?t=98634>

Thx all,

Shawn

 

[jeffreyinberthoud]

Ive seen 170.750 and several athers in that range pop up on close call as I drive by the federal building in the lakewood area ,Never tried to track them just logged them
there is also a 138. something..... data freq from same

 

[ChrisP]

All,

I came across two trunked frequencies today however have yet to determine what system they are part of. The frequencies (167.925 & 170.750) are both in the govt. band and can be decoded with the Pro-96 in FM mode.

I just located them today and have heard some conversation however nothing to identify their location yet. I cannot locate any control channels at all in the 162-174 MHz band.

My location is 40 miles north of Denver (Gilcrest, CO).

In a separate thread I'm also trying to determine what trunked systems 407.725 & 419.900 are part of and also what trunked system 415.850 & 416.000 are part of? <http://www.radioreference.com/forums/showthread.php?t=98634>

Thx all,

Shawn

Shawn, I am confused. You say you found some trunked frequencies, but you haven't found any control channels. How have you decided these two frequencies are trunked if you haven't found any control channel? Of are you saying you found 2 P-25 digital channels?

In order for these VHF frequencies to be part of a trunked system, there has to be a control channel associated with them.

BTW, 170.7500 MHz is used quite often by the US Marshals at federal courthouses.

- Chris

 

[rfburns]

167.925

It seems like 167.925 should be WAPA or BOR, but I don't have my data with me to look it up. I could be wrong. What do they talk about on those two frequencies?

 

[ScannerSK]

Chris,

They are P-25 digital channels. I guess now that I think about it they would not have to be trunked. Would there even be a need for a control channel? Possibly they are stand alone P-25 channels then?

There may be an associated control channel that I'm not capable of receiving in this area?

Thanks for the heads up!

I'll try to catch some conversation on the freq's.

Shawn

 

[ChrisP]

Chris,

They are P-25 digital channels. I guess now that I think about it they would not have to be trunked. Would there even be a need for a control channel? Possibly they are stand alone P-25 channels then?

There may be an associated control channel that I'm not capable of receiving in this area?

Thanks for the heads up!

I'll try to catch some conversation on the freq's.

Shawn

Hi Shawn...

Yes, if they were part of a trunked system, then there would be an obvious control channel transmitting a continuous data stream. (There are exceptions, such as LTR, but that would not apply to a system with P-25 voice channels) The transmitter for the data channel would located with the voice channel repeaters, so you would be able to receive it with the same signal strength as the voice channels you are hearing. The radios using the trunked system would have to receive that data channel in order to work with the trunked system, so it's not likely that you could hear the voice channels but not the control channel.

Once you find that control channel, you can look at the information being transmitted in that data stream using software such as Trunker, Unitrunker or PRO96COM. That would let you know what the associated voice channels are supposed to be.

VHF trunking in the federal bands is rare, but not unheard of. I guessed from your original posts that you assumed that if you found some digital voice traffic, it must be trunked. Not true...

Keep listening and see what you find out!

- Chris