Project 25/APCO 25

redhawk9 · #1 (**permalink**) 11-07-2009, 02:50 AM

I have been perusing a lot of different scanners and frequencies lately and I see reference to Project 25 (Colorado, a lot of Nevada) trunking system and I see reference to APCO 25 (LAPD/LAFD/LASD). My question is, what are the differences in the frequency bands? If I don't go to L.A. more than about once every couple of years, does it make sense to get a different scanner than the ones I already have (GRECOM, RadShak) that are double and/or Triple trunking?

Info to: rimmer@mail2joe.com

DaveNF2G · #2 (**permalink**) 11-07-2009, 08:21 AM

APCO 25 and Project 25 refer to the same suite of standards for digital radio communications and trunking. The "P25 CAI" and the protocols for the 9600 bps control channel signals for digital trunking are the output of APCO's Project 25.

Previous APCO projects resulted in standards for trunking generally (such as Project 16, which is why one of GE's first trunked systems was called "Sweet (suite) 16").

The standard has nothing to do with frequency bands. P25 trunking can be used on any frequency where trunking is permitted, including VHF, UHF, and 700/800/900 MHz. To monitor any digital system, you need a scanner that is capable of decoding digital voice transmissions (P25 CAI) and, if the system you wish to monitor is in fact P25 trunking, a scanner that can interpret the 9600 bps datastream.

The designation for a true P25 trunked system should be "P25 Exclusive." The RRDB is fairly accurate about this, but being reliant on user submissions can introduce errors. It's best to confirm the nature of a system you want to monitor in the appropriate state forum.

redhawk9 · #3 (**permalink**) 11-07-2009, 04:41 PM

OK-I think...

If I understand correctly, Project 25 and APCO25 are the same frequency protocols?, so if I go down to L.A. for a weekend, and I bring my GRECOM MULTI TRUNKING scanner and my laptop (has the software to program my scanners), I should be able to receive LAPD, etc...? Or do I need to upgrade my scanner to a APCO25 compliant scanner?

N_Jay · #4 (**permalink**) 11-07-2009, 08:12 PM

The proper name is Project 25. APCO 25 is an incorrect name, (no longer recommended to be used).

Project 25 (P25) is a set of standards, that include a Common Air Interface (CAI) as well as other "protocols". It is designed to be as frequency non-specific as practical.

So calling is a "Frequency Protocol" is also a misnomer.

LAPD does use P25 on T-Band UHF in conventional mode.

mdulrich · #5 (**permalink**) 11-07-2009, 11:02 PM

Quote:

Originally Posted by redhawk9

OK-I think...

If I understand correctly, Project 25 and APCO25 are the same frequency protocols?, so if I go down to L.A. for a weekend, and I bring my GRECOM MULTI TRUNKING scanner and my laptop (has the software to program my scanners), I should be able to receive LAPD, etc...? Or do I need to upgrade my scanner to a APCO25 compliant scanner?

What model number is your scanner?

Mike

DaveNF2G · #6 (**permalink**) 11-08-2009, 09:21 AM

To track P25 Exclusive systems, you need a GRE PSR-500 or PSR-600.

To monitor users of the P25 CAI on conventional channels or mixed-mode trunked systems, you also need the PSR-500 or PSR-600.

If you have some other model GRECOM scanner, then you will not be able to monitor voice traffic on such systems.