SDS100: SDS-100 or any Uniden scanner... P25 identification

ecarvalho

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#1
I’m in need of guidance.
Recently I’ve found a P25 transmission in a frequency not listed in the RR database. So I proceeded to listen and take notes.

I found the NAC and also concluded that there are clear and encrypted transmission. I see “P25” and “LINK” display. “ENCRY” when the transmission is encrypted.

Now I want to build this system, listen more and later submit it to RR.

My doubts are:
How do I determine if this is a P25 One Freq., a P25 TDMA, a Motorola ... system?

How do I determine the control channels?

So far, via ID Searching, I identified only one talkgroup “1”.

My apologies for the rather noob questions.


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Last edited:
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#2
A P25 control channel broadcasts continuously. If you hear voice on the freq it's not a control channel.

Look up the frequency on digitalfrequencysearch and that will tell you who it's licensed to, as well as other frequencies licensed to the same entity.

If the only talkgroup is 1, it's probably a P25 conventional system, and there may not be a control channel, or any other frequencies involved.
 

ecarvalho

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#3
I will look it up!
Yes, talkgroup “1” is the only one so far.
I appreciate


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ecarvalho

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#4
It is not there in the digital search site. Tho I also found that the frequency in question is common use. So looks like this is a one frequency P25 system


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ecarvalho

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#6
Troy
Haven’t heard much that makes sense and most traffic is encrypted.
409.0750 NAC 293


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ecarvalho

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#9
Ok I saw that before but there was no NAC listed so I thought the one I found was different. Guess not?


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ecarvalho

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#12
Thanks guys for your help
Its a pretty active frequency and they talk about posts, roll calls, child care center, but responses are mostly encrypted.


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ecarvalho

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#15
Here I found something...

Common Use Channels
Worth monitoring are these common
-
use frequencies
which are available for use on a shared basis by any
federal agency: 163.1/168.35, 163.7125, 168.6125,
173.625/167.1375, 407.525/416.525, 409.05/418.05,
409.075/418.075, 409.3375/418.3375, 412.825,
412.8375, 412.85, 412.8625, 412.875, 412.8875, 412.9
and 412.9125. The older wide
-
band channels are:
408.4, 418.05, 418.075 and 418.575

Source: http://henney.com/chm/0117/chm0117.pdf
 
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