Decoding P25

Ensnared

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#1
I have successfully utilized Pro96.com to obtain P25 trunking using a PSR 500. However, when I downloaded this, and attempted to obtain the information, the towers were not visible like before. The ID of the system was not there. There were no affiliations. It appeared there were two different versions of this with one of them wanting $$$$.

So, I went to Unitrunker with my PSR 500 and attempted to get it to decode. I might add the P25 800 MHz trunking system is still being installed. I have loaded all of the known system frequencies into the radio, put it in analyze mode, and watched it do nothing even with a very strong CC. It showed my PSR 500 to be running.

I would appreciate some help.
 
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troymail

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#2
I use Pro96Com without any issues - I am not aware of a "paid' vs. "free" version and I get everything I need from the available software.

I find that it isn't uncommon - even for systems that are fully operational - to be missing some expected parameters such as a periodic callsign broadcast.

If the system isn't live, you may not see any affiliations....

What else can I do to help?

I've tried Unitrunker in the past but prefer and regularly use Pro96Com.
 

Ensnared

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#4
Up and Down

As I indicated, I will be attempting to decode the local established radios systems to see if it still works well. Yes, I had no trouble with either of the systems, one VHF and one 800 mhz trunking systems within my county.

I did observe a systematic emission code pattern showing different cities within the target area. I am assuming they are adjusting and making modifications. During the day, on occasion, you can see an occasional P25 TG show up, but most of the system has been using EDACS during this installation process.

I don't know if is accurate or not, but I believe that they are toggling between analog and P25. I don't know if they have set up a default position for the user in the event they encounter transmission difficulties on the new system. By this I mean, if P25 is screwed up for some reason, it kicks it back to EDACS.

I have been told that the radio system is based on the exact frequencies used in EDACS.

Again, I am going to practice on known territory before I move forward with my analysis. I seriously doubt there are going to be any significant changes to the system during the holidays.

Thanks.
 

troymail

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#5
As I indicated, I will be attempting to decode the local established radios systems to see if it still works well. Yes, I had no trouble with either of the systems, one VHF and one 800 mhz trunking systems within my county.

I did observe a systematic emission code pattern showing different cities within the target area. I am assuming they are adjusting and making modifications. During the day, on occasion, you can see an occasional P25 TG show up, but most of the system has been using EDACS during this installation process.

I don't know if is accurate or not, but I believe that they are toggling between analog and P25. I don't know if they have set up a default position for the user in the event they encounter transmission difficulties on the new system. By this I mean, if P25 is screwed up for some reason, it kicks it back to EDACS.

I have been told that the radio system is based on the exact frequencies used in EDACS.

Again, I am going to practice on known territory before I move forward with my analysis. I seriously doubt there are going to be any significant changes to the system during the holidays.

Thanks.
I've watched numerous systems (Motorola and EDACS) transition to P25 "over time" using their existing frequencies.

Example:
Legacy: https://www.radioreference.com/apps/db/?sid=381
New: https://www.radioreference.com/apps/db/?sid=8201

Baltimore City MD transitioned very early one morning by bringing over a couple of their existing frequencies and sets of users at a time.

Baltimore County MD actually came online for 1-2 days on a weekend and then reverted to the old system for the next week to prove the new system would work.

During the setup and testing, they seem to "borrow" frequencies from the live system that is being replaced (at least a few) to use for the P25 system testing.

I've always wondered how this is managed particularly should there be a major event that might require the full set of frequencies to support the live legacy system.

This one:

Old system (Site 7):
https://www.radioreference.com/apps/db/?sid=386

New system:
https://www.radioreference.com/apps/db/?sid=9339

is in active buildout. The reported "P25 system" information is a bit ahead of itself I suspect because the information provided came from someone "in the know" or just pure speculation. There is (or was last time I was there) at least a P25 CC and one voice frequency active on the "new" system. One of the only talkgroups active on the P25 system is more or less a patch from the EDACS system. I believe (as is the case many times), they have a couple of users using the new system and P25 radios for testing (I saw this when Maryland FiRST sites were in testing before coming online as well). They very likely have the old system radios in their units to fall back should their be any problems with the new system tests. This system has been delayed a couple of times now and is reported to be coming up sometime early in 2018 after they engineer and install an additional tower that became required during field testing.
 

Ensnared

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#6
One more question. Is it possible to use Unitrunker or Pro96.com with a 436HP, without any discriminator tap? If decoding requires the use of my PSR 500, I am out of luck because a friend buggered up the BNC module on this unit. Hence, getting enough bars to decode can be problematic.
 

Ensnared

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#7
Bingo

They could be using a non-standard bandplan. Both Pro96Com and Unitrunker should be able to find that for you.
Now, I am really confused, but successful. I went back into a known P25 Phase II P25 system here in Waco, Texas. I followed the various steps and found an active CC. I put my PSR 500 into analyze with 5 bars showing. Guess what? It started decoding like it has in the past, no problems whatsoever.

However, when I first attempted this in Temple, nothing showed. Another listener was able to decode the Bell P25 system in the Killeen, Texas area using Unitrunker.

Since this person was successful in decoding the system in question, I am going to attempt to decode Bell County provided I can obtain 5 bars (unsure about threshold). When I first tried to activate Pro96.com, I heard a strong CC with around 4 bars showing, but no data was coming out.

I suppose the system is ripe for analysis since another listener was able to perform an analysis.

Now, I will return to Temple and monitor, again. Hence, I got it working in Waco. I am not screwing up the software.

Onward through the fog.
 
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#8
One more question. Is it possible to use Unitrunker or Pro96.com with a 436HP, without any discriminator tap?
You will have to look at the software and scanner documentation to see if the 436HP is on the list of scanners that have a data output connector that the software can use.
 

Ensnared

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#9
Unitrunker Working in Waco

As indicated, I have successfully activated both Pro96.com and Unitrunker here in Waco. Both of these software programs were activated without the slightest problem. The information is coming out as if Moses struck a rock.

So, I wonder, why don't these haven't worked in Bell County. Again, I might have been a bit premature in my attempt to do so.

Now, there is no excuse. I "should" get some reception next week when I return to Bell County. I will use both systems to ascertain active talk groups/affiliations.
 

Ensnared

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#11
CC: Recognized Sound

How do you know it was a control channel?
I know what a Motorola CC sounds like. When I put the PSR 500 in analyze mode and toggled through the 19 frequencies that were programmed, it "was" the only that emitted that definitive noise I know to be a CC. I believe I previously documented what I believed to be an active CC on the Bell System. I will look later to see if I was correct.

The same exact noise was easily recognized here when I activated the Waco P25 system. In fact, if I were to record this sound and then compare it to what I heard at Morgan's Point while monitoring the Bell System, I would be able to determine, "yes, indeed, these sound alike."

This was the same method I used when I analyzed the Woodway VHF Trunking System nearby. I started with the CC noise and built the system based on information obtained from Pro96. Later, they threw me a curve ball by changing the frequencies. I later learned they bought them in pairs at an marine band auction in Galveston, Texas.

Since I've not experience a successful run with the aforementioned decoding software, I cannot say I've heard the Bell County alternate channels yet.

Here is what is odd. When I heard the CC on the Bell System, no data came out of the software. It showed no AC, no CC, no system information, nothing. When I used the Pro96 on the Waco system, all of the above was spewing forth like the ejaculate from a seventies porn movie.

When I return to Bell County on Monday, I will see what happens when I attempt to analyze the system, once again.
 
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Ensnared

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#12
Nothing in Bell County

I hooked up the PSR500 with about 5 bars showing. I then put it into analyze mode and toggled to the CC for the new Bell County P25 system, or what I believe to be the CC based on past experiences. Typically, I see additional information below the CC, but the screen showed nothing.

When I followed the same steps with Unitrunker and Pro96, the Waco P25 system responded. It displayed talk groups and affiliations, etc. I did not look to see if there was system information below the CC in analyze mode. Tonight, I will see if there is system information on my PSR 500 in Waco.

Nothing happened in Bell County.

I am very puzzled. Another listener came to this area, activated Unitrunker and managed to find the CC/AC and other radio parameters. I wonder what I'm doing wrong?

Help!
 
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