Help programming P 25 STL City

[ZOU4Life]

I just got a Uniden BCD396XT digital scanner and have no idea how digital trunked systems work. I'm trying to program STL city P25 public safety (Fire, Police, EMS) and don't know what a talkgroup vs a site vs system frequencies are. Could someone please help? Thanks!!!

[lynxrufus]

I don't have a Uniden scanner so I can't help you navigate the menus. But, assuming you can do that, step by step programming of a P25 is described on the following page.

http://info.uniden.com/twiki/bin/vie...TrunkedSystems

There are only 3 required steps.

1. Create a system. There are no required properties. You can use the defaults, except that, if you're not going to program talkgroups, you should make sure that 'ID scan/search' is set to 'search.'

2. Create a site. Once again, there are no required properties.

3. Create at least one frequency for the site.
I'd suggest 855.63750 which is the St. Louis North control channel.

That should be all the programming you need to do. If you enable the system and enter default scan mode, you should recieve all talk groups: police, fire, EMS, the city jail, sheriff, street dept., water dept., etc. (in a Radio Shack / GRE scanners, it's called scanning a wildcard talkgroup).

That's my suggestion, for what it's worth. I hope it helps. You can refine the programming (add alternate control channels, program talkgroups) later.

[ZOU4Life]

That makes a lot more sense now. Do I only need the 855.63750 control channel, or should I program the blue alternate channels too? If I only need the control channel what's the point of the other frequencies in black?

And if the whole city's EMS uses one talkgroup, why is there a separate north and a south control channel?

Also, is the St. Louis P25 the standard, or One frequency trunk? And when I'm programming the sites on my scanner it asks for a LCN and Number tag. Do I need those?

Thanks!!

[lynxrufus]

You should only need to program the 855.63750 frequency. The alternate control frequencies are available in case the regular control channel frequency is unuseable for some reason. Theoretically, they could change the control channel to any of the alternates at any time but I'm not aware of the city doing that.

The frequencies in black are voice channels. Your scanner will receive data on the control channel that will control which voice frequency the scanner will tune to. When you hear a transmission, you'll be hearing what's on one of the voice frequencies (in black) but you don't have to program the voice frequencies. The scanner can read the voice channel frequencies on the control channel.

St. Louis is a standard P25 trunking system, not a one-frequency (non-trunked) system and it's not LCN. You don't need a number tag. The south tower provides better coverage but, as long as you can receive signal from the north tower, you shouldn't need it. City EMS has more than one talkgroup but they all use the same control channel.

It might seem ridiculous that you only have to program one frequency but that's trunking. If you program the scanner with the one control channel frequency, you should hear quite a bit of traffic, surely some talkgroups you don't want to hear. That's when you will want to either lockout talkgroups or program talkgroups to only scan for the talkgroups you want to hear. But I'd get the system programmed and listen to it first and worry about talkgroups later.

[ZOU4Life]

Okay sweet. I can hear city now. I have just the primary and alternate control channels programmed for City north and south. I also have Fire and EMS talkgroups programmed but I'm still picking up other talkgroups like police. How do I only hear the talkgroups I have programmed?

Also, my scanner has an APCO Band Plan on my sites. What is that? Thanks!!!

[lynxrufus]

Originally Posted by ZOU4Life

How do I only hear the talkgroups I have programmed?

You'll need to go to the program system menu and set the 'ID scan/search' property to 'scan'.

The description of this property says: "Choose whether the scanner only checks the Talk Group IDs that you program ( ID Scan ) or checks all the Talk Group IDs it can find ( ID Search ) when scanning this site."

Other than that, I don't know. All I know is what I read in the manual. I don't have a Uniden scanner and don't have any experience with one.

I don't know about the band plan but I doubt it's anything to worry about in the case of the city's P25 system.

[ZOU4Life]

Yup! That fixed it! Do you know what a number tag is, or a NAC? Those are the only things I'm still confused about. Whats the difference between a number tag and a quick key? Thanks!!

[lynxrufus]

NAC is a network access code which performs a similar function to coded squelch. The P25 system should take care of this automatically.

Number tags and quick keys are Uniden things I know nothing about. They apparently let you enable or disable or access channels or systems while scanning.

[nick1427d]

Zou,

Do you have a windows based computer? If so download a programming software. I was a non-believer in using a computer to program my scanner but the way things are set up around here you're better off doing it that way. Plus it's much much easier to see how you have things set up especially with system keys quick keys etc. If you plan on monitoring any of MOSWIN and the counties P25 system you'll want software.