P25 Programming HP2 and BCD436HP

[Astialis]

Hi!
I will try to make this post as short as possible.

Back in December I bought two Uniden scanners, a BCD436HP and a HomePatrol 2. I’ve since been trying to get them to work with a local police P25 system. With the help of the BCD436HP (and the FCC website) I was able to identify a few Control Channels. These frequencies appear with a constant DAT in the BCD436HP. One of these frequencies is 851.3000. So, what I did was, I created a new P25 Trunk system in the HP2 and analyzed it with the Analyzer option. In the Analyzer I chose the “Current Activity” option, and it quickly gave me a few other frequencies, with different colors. These frequencies are 851.3062 (blue), 851.8062 (white), 851.2187 (white) and 851.7562 (white). The first thing I noticed was that the Control Channel was off by 6.25khz (remember, the one I found was 851.3000, while the one the HP2 found was 851.3062).

Now it gets interesting. If I create a new P25 trunk system with the HP2-found frequencies, I get no audio or conversations. If I subtract the 6.25khz on those frequencies (meaning: 851.3062 is now 851.3000, 851.8062 is not 851.8000, and so on), and create a new P25 trunk system and use those frequencies, I still get no audio, BUT, if I create a new P25 One Frequency system, and input those frequencies (the one without the 6.25khz) then audio can be heard, but I know I’m missing part of the audio since it’s not in trunking. So, in summary, the frequencies only work when:

1. I subtract the 6.25khz
2. Use them in a P25 One Frequency system, NOT on a P25 trunking

I have confirmed that the system in question is actually a P25 Trunk system. By the way, the RR and Sentinel database entries are both useless and outdated. So, either the TRS is sending the wrong signals, or both my radios are bad/damaged...

Has anyone seen/experienced this before?

 

[marksmith]

Doubt both radios are bad.

I have never run into what you ate describing. Can you advise which system you are discussing? Maybe someone here will have some experience with it, especially if it is listed in the RRDB.

Being able to look at what RRDB has, even if you believe it to be out of date or inaccurate might generate some clues.

Mark
536/436/WS1095/HP1/HP2/996T/996XT/996P2/396XT/325P2/PSR800/15X/others

 

[sparklehorse]

I don't know if the band plan in Puerto Rico is different from mainland US, so I can't say whether 851.3 is correct, or 851.3062. What happens if you enter ALL of these frequencies into your 436 as conventional channels and set the audio type to 'All'? Give that a try, it should help you figure out what is correct. Also could it be that your control channel is for an analog trunk system? How is it you are sure it's for a P25 system? Are you getting that info from the HP2?
.

 

[Astialis]

Hi again!

I don't know if I can post links, let's try it. It's this system:

PolicÃ*a de Puerto Rico (PRPD) - Red de Radio Interoperabilidad Trunking System, Various, Puerto Rico - Scanner Frequencies

As you can see, most of the frequencies posted there have the extra 6.25khz too, so I would think that someone made a similar test as the one I made. As far as I know, the local police is still in the process of converting from the old analog system to this new one (although it's been 4 years now since the P25 started operation). I can still hear conversation in the old analog frequency.

Maybe they did this on purpose so that people cannot track them with scanners? But then again, their radios would not work either....

I did create a conventional P25 system, and I can hear the police clear as day, I just can't correctly follow a conversation. Also, I know it's P25 because, I made a custom search in the 436HP, and the scanner would pause whenever there was audio, and "P25" would show up at the bottom of the LCD screen.

I was told this system is encrypted, but if it were, I wouldn't be able to listen to audio as a conventional P25, right? Also, the Analyzer would show Red activity if it were encrypted, and is not showing up anything Red so far....

I would love to test this on a radio other than Uniden, just to make sure. I do have an old RadioShack Pro-106 somewhere that I could try...

 

[sparklehorse]

Looking at your system in the database, 851.30625 is listed as the only frequency for Site 9. That tells me it is most likely a one-frequency P25 system. I have no personal experience with systems like that, but as I understand it, if you program the system in your radio as a one-frequency system type it should track it just fine. You only want to put in the ONE frequency though. I would not bother entering the other frequencies, even though your HP identified them. Your radio should get all the information it needs to track the system properly from the ONE control channel. Give that a try and see if it begins to track conversations. Also you might be having reception problems, which are common with P25, so even if it is tracking properly you might still be missing some transmissions. But that's a whole 'nother can of worms!

.

 

[marksmith]

Based on the large majority of sites being one-frequency control channels, I would also try creating a p25 system and entering the one frequency for the strongest site to you, and see what happens.

Mark
536/436/WS1095/HP1/HP2/996T/996XT/996P2/396XT/325P2/PSR800/15X/others