Am I picking up a digital trunked system via conventional frequencies?

[AE4VE]

I was using the SEARCH function (on my Radio Shack Pro-106 scanner) to search for random frequencies and it picked up a few 800 MHZ P25 frequencies with the NAC codes and everything.
What is confusing to me is that in my area (Houston County, Georgia), our Sheriff/PD/FD/EMS/etc. are all on the P25 digital trunking simulcast system, except for a couple random ones popping up on 150-ish MHZ conventional frequencies.. and the ones that my scanner search picked up were the same officers and dispatchers that are on the P25 digital trunking system.
Can anyone explain why I am able to pick up our local trunking system on the conventional 800 MHZ P25 frequencies that it picked up? I am honestly confused as to why this is happening.
Also, should I program these frequencies into my scanner? or would that interfere, somehow, with the digital trunking system that I already have programmed to my scanner?

Any help or info would be greatly appreciated.
Thanks, in advance.

John.

 

[marksmith]

You are hearing voice channels from the p25 system. However, since they are not controlled by the control channel on the p25 system, they won't follow a good conversation and will be sort of random. One second you might hear police on that frequency, the next transmission might be a trash truck or something else on the system.

You are listening to a controlled trunked system in a conventional uncontrolled mode, meaning random transmissions on the various voice channels, but not in a way you can actually monitor specific departments or talk groups, as the talk groups are randomly moved from frequency to frequency by the control channel of the system.

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[W4ELL]

Are the 800 mhz frequencies you hearing part of the P25 trunk system? I assume you are talking about this one:

Houston Peach Regional Radio System (HPRRS) Trunking System, Various, Georgia - Scanner Frequencies

I am with Mark on this one, I'd bet that the frequencies you are hearing in search mode are frequencies of the P25 system.

 

[AE4VE]

@marksmith
10-4. That makes perfect sense. Thanks for the quick reply.

@W4ELL
yes, the frequencies I am picking up are the same ones in the trunked system. and yes, that is my area's trunking system.

PROBLEM SOLVED!!!

Thank you both for the info.

 

[marksmith]

@marksmith
10-4. That makes perfect sense. Thanks for the quick reply.

@W4ELL
yes, the frequencies I am picking up are the same ones in the trunked system. and yes, that is my area's trunking system.

PROBLEM SOLVED!!!

Thank you both for the info.

The first non-trunking scanners that could get 800mz were like that. You monitored a dozen or so frequencies, but you often lost the conversation as it switched frequencies on you, and you had to keep locking out the control channel or alternates as it blasted noise.

Then they came out with trunking. The control channel or alternates direct your scanner to the appropriate assigned voice frequencies as the talkgroup bounced around among them. Huge improvement, and talkgroups became the "channels".

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