P25 One Frequency trunked system

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ofd8001

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I need some input on setting up a P25 One Frequency trunked system. Here is the scenario:

The Kentucky State Police is a multi-cast P25 Conventional System. I understand that if I set this up as a P25 One Frequency trunked system, my 536 will decode additional data, such as Unit IDs. That's why I'm interested in going this route versus setting it up as a "regular" conventional system.

Where I'm located, I can receive the primary and secondary frequencies from three different dispatch offices, for a total of six frequencies.

Here is where I'm at a loss. Do I want to create six different sites, each having a single frequency, or can I consolidate all six frequencies into one site?

Thanks!
 

jonwienke

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Here is where I'm at a loss. Do I want to create six different sites, each having a single frequency, or can I consolidate all six frequencies into one site?
It depends. If all the transmitters are at the same physical location, you can put all the freqs in one site. But if there are 3 different physical locations, each location should be its own site, with whatever freqs are used at that location.

That will also let you tag each site with actual GPS coordinates so that Location Control can turn various sites on and off as you're on the go.
 

ofd8001

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This is kind of a convoluted system, but gets the job done for them mostly.

One of the sites is here in Louisville. There are two different transmitters each using a separate frequency. There is different traffic on each - for example if there is a pursuit, the units not involved with that are directed to use the alternate frequency.

A second second site (also with two transmitters/two frequencies) is south and the third site (two frequencies) is east.

I'm thinking I'll do the six site programming.

Thanks!
 

jonwienke

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I would recommend 3 sites, with 2 frequencies each.
 

ofd8001

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Well I got it programmed and more or less functional. I think the price I'm paying is a reduction in reception. I seem to be hearing more traffic when this system is being scanned as a conventional system versus one frequency P25.

A firmware update would be nice to decode Unit ID information for P25 conventional systems. Though it may be impossible from a hardware basis other there may be more important things on Uniden's plate.
 

jonwienke

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Well I got it programmed and more or less functional. I think the price I'm paying is a reduction in reception. I seem to be hearing more traffic when this system is being scanned as a conventional system versus one frequency P25.
Probably not, but here's how you can tell. Program the system as both conventional and one frequency, but arrange your favorite list so that they are next to each other, but the one frequency version is scanned first. If it's missing traffic, the scanner will move on to the conventional version of the system, and you'll hear the traffic there. Compare how much you get on the one frequency vs conventional. If the one frequency system is working, you'll get most traffic there. The only time the conventional system will get a hit is if someone keys up just as the scanner is switching from the one frequency to the conventional system.

If the conventional system gets most of the hits, then you have a problem.

One other thing: Make sure the one frequency system is set to ID search instead of ID scan. Otherwise, all talkgroups you haven't programmed will be ignored by the one frequency system.
 

ofd8001

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I tried also programming the convetional system as part of the Favorites List. My sense was about half the time I was hearing transmissions on the One Frequency Trunk System and the other half on the conventional system.

One puzzling thing was that with the One Frequency Trunk System, I would often hear the unit to dispatcher side, but not the dispatcher to unit, or vice versa.

All considered, I'm probably stay with the conventional system programming and give up getting Unit ID information.

Thanks for the advice!
 

hiegtx

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I tried also programming the convetional system as part of the Favorites List. My sense was about half the time I was hearing transmissions on the One Frequency Trunk System and the other half on the conventional system.

One puzzling thing was that with the One Frequency Trunk System, I would often hear the unit to dispatcher side, but not the dispatcher to unit, or vice versa.

All considered, I'm probably stay with the conventional system programming and give up getting Unit ID information.

Thanks for the advice!
One thing I ran into, using One Frequency Trunked systems for some local DMR users, was that using ID Search, if there was not at least one 'dummy' talkgroup, reception was erratic to the point of sometimes being non-existent. Once I added a place-keeper ID, it improved, though some transmissions still flowed to the conventional system which was next in line in the Favorites list.
 
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