Monitoring Gilbert PD with Pro-96

[JonHanson]

I picked-up a Pro-96 this weekend (with the DSP patch) and have been programming it through Win96. I entered the Maricopa County system in one bank and it worked fine.

Because I live in Gilbert I'd like to monitor Gilbert's police as well. I have the latest copy of the Southwest Frequency Directory and programmed in the control channels for "Simulcast D" (867.225 and 868.3625) and set the bank and both channels to Motorola mode. When I scan this bank (set to "open" mode), however, I never hear anything and I've let it scan for hours. When I switch to manual mode in this bank I can hear the control channel and the radio indicates that it recognizes a 9600 baud control channel. The percentages that it toggles through are always above 90%.

Can someone tell me if I've got something setup wrong? Even better: can someone who monitors the Gilber PD tell me their settings?

 

[JonHanson]

I think I figured out what the problem is but it's still puzzling. I found another control channel on 868.275 that, when scanned, yields the Gilbert Police talkgroups. This control channel doesn't come in nearly as strong as 868.3625, but scanning 868.3625 doesn't yield any voice even in "open" mode. I guess that control channel isn't working for whatever reason. Does anyone know anything about that?

 

[AZScanner]

I think I figured out what the problem is but it's still puzzling. I found another control channel on 868.275 that, when scanned, yields the Gilbert Police talkgroups. This control channel doesn't come in nearly as strong as 868.3625, but scanning 868.3625 doesn't yield any voice even in "open" mode. I guess that control channel isn't working for whatever reason. Does anyone know anything about that?

I have an explanation that might make sense for ya... I may be a little inaccurate on the technical details but I figure nearly 20 years of playing with scanners qualifies me to provide a pretty good laymans' explanation:

The site controllers on the new system work like a cell tower does. There may be numerous towers in the area, but unless one of the radios on the system affiliates itself with the one on 868.3625 that controller will not bother passing trunking assignments along, since, as far as it's concerned, there's no one to pass them to. The reason the one near you just yammers on saying nothing but "hello, anyone there?" is because no one is logged into it. If someone does log in, then you will start to hear traffic being passed along from the other sites on that freq.

Also it's worthy to note that the sites overlap one another so that if one goes down, the other serves as a backup. Chances are this one is just that - a backup to the primary one you've been monitoring - if the primary goes down, the radio's will search for another active site, and if they wind up on yours, voila.

Now, since there's generally ALWAYS at least one radio communicating with the site closest to the PD station, that site should always be carrying system messages to the radio's (and as a result, your scanner). That's most likely the one you're monitoring right now.

I hope that helps. These new systems are tricky to monitor. Believe me when I tell you that "I don't think the Empire had wookies in mind when they designed her, Chewie". In other words, scanners don't exist to a site controller, so that's why you're not hearing anything on that one. Maddening isn't it? Makes one miss the good old days of VHF/UHF.....

-AZ

 

[JonHanson]

I guess that makes some sense. It seems kind of strange that no one had associated with that particular control channel becuase it is up on Tompson Peak (if the Southwest Frequency Directory is correct). With a view like that I figure that everyone can probably see that signal the best but I'm new to this trunking thing so I'm definately not an expert.

 

[kikito]

It seems kind of strange that no one had associated with that particular control channel becuase it is up on Tompson Peak (if the Southwest Frequency Directory is correct).

Did you check the database on this site?

It lists 867.0750 as the control channel for Thompson Peak....

The only other two control shown are 868.2750 and 867.8250 both for the Simulcast sites....

http://www.radioreference.com/modules.php?name=TRSDB&sid=2082

 

[DanRollman]

I guess that makes some sense. It seems kind of strange that no one had associated with that particular control channel becuase it is up on Tompson Peak (if the Southwest Frequency Directory is correct). With a view like that I figure that everyone can probably see that signal the best but I'm new to this trunking thing so I'm definately not an expert.

The Thompson Peak site is only an Intellirepeater. In very simple terms, that means that it is ONLY used when the regular, ground based site does not cover the area where a radio is. Only then will the radio affiliate with Thompson Peak, as I understand it. That's also why Thompson Peak has significantly fewer frequencies... Because there should be much less activity on it than the main Mesa simulcast sites around the city. Think of it as little more than a "gap filler" when needed.

The same is true of the South Mountain site for Phoenix. It's an Intellirepeaters. Not used, unless it MUST be used because no other site will work, even marginally.

Note: This is a highly oversimplified explanation, but you get the idea.

Dan

 

[DanRollman]

I guess that makes some sense. It seems kind of strange that no one had associated with that particular control channel becuase it is up on Tompson Peak (if the Southwest Frequency Directory is correct). With a view like that I figure that everyone can probably see that signal the best but I'm new to this trunking thing so I'm definately not an expert.

The Thompson Peak site is only an Intellirepeater. In very simple terms, that means that it is ONLY used when the regular, ground based site does not cover the area where a radio is. Only then will the radio affiliate with Thompson Peak, as I understand it. That's also why Thompson Peak has significantly fewer frequencies... Because there should be much less activity on it than the main Mesa simulcast sites around the city. Think of it as little more than a "gap filler" when needed.

The same is true of the South Mountain site for Phoenix. It's an Intellirepeaters. Not used, unless it MUST be used because no other site will work, even marginally.

Note: This is a highly oversimplified explanation, but you get the idea.

Dan

 

[jamiewmorris]

did you set the bank type to MO?

On the Pro-96 you have to go into each bank and change it to what type of system you want to monitor. Manual onto a channel in that bank you have programmed, and then hit the PGM button, and then the TRUNK button, then hit the MODE button until it displays MOTOROLA. This is one problem I had when I first got my PRO-96. You may have already done this, but this was a simple solution try to what it sounded like you were talking about!

 

[Thunderbolt]

After doing a lot of experimenting, I am able to track part of the system. I set my 796D to the following:

Base Freq: 406.000 MHz

Space Freq: 12.5 KHz

Offset CH: 380

The above configuration works great for the following frequencies: 406.2250, 407.0500, 408.1000, and 408.3250 MHz. However, when the talkgroup falls onto 410.5250 MHz., my scanner passes right over it. Any clue as to how I could change the setting to include the later of the freqs so it will track properly?


73's

Ron

 

[kikito]

The above configuration works great for the following frequencies: 406.2250, 407.0500, 408.1000, and 408.3250 MHz. However, when the talkgroup falls onto 410.5250 MHz., my scanner passes right over it. Any clue as to how I could change the setting to include the later of the freqs so it will track properly?

Ron

Did you mean to post this reply to this thread?

Anyway, you might need a second set of Base/Offset, maybe?