Tallahassee FL goes 800 Mhz!

Note: I am working on this page (and subsequent links from the page) on a daily basis as the City of Tallahassee Trunking system develops. Since trunking is new to public safety here in Tallahassee, there are alot of folks with LOTS of questions. Hopefully I will answer most of them here. Please send me comments and suggestions. Sometimes it takes another view to point out the mistakes or omissions!

Tallahassee has begun the transition of moving all of city communications to the new 800 Mhz 15 channel trunking system. City departments have for years used a "hodge podge" of radio frequencies but now we are moving into the 21st century!. You can check out the "old" frequency list that I have maintains since the early 80's,the Tallahassee Frequency Guide . As you can see, Tallahassee has used everything from low-band to UHF.

A Trunking Primer

In a trunking system, a computer controls and assigns the frequencies in use on a real time basis and uses a "control channel" to keep up with this housekeeping. Each time the radio Push to Talk (PTT) is pressed and you begin to speak, the controller assigns you a frequency to talk on (and the group ID). When the PTT is pressed again, you might be on another available frequency and so on. For conventional scanning, this will drive you nuts because the user is not staying on ONE frequency but is jumping around! Not like the old system at all! This would not be so be if you had one agency to monitor but a whole city??? Not only do you have Police and Fire, but let's add Sanitation, Animal Control, Traffic Light division and so on. There are several things you need to know to enjoy scanning again!

Tallahassee will be using a Motorola System II trunking system (let's thank the engineers for this!). What his means is two fold.

1. Analog - meaning not digital. You can hear this trunking system on a conventional scanner.
2. Motorola System II - System II controller delays "jumping frequencies" so you have up to 5 seconds for a reply to keep the conversation on the same frequency

To better understand what trunking is, lets use an example of the Tallahassee Police Department (TPD). TPD has been on UHF for years and currently operates a 6 channel UHF system on the following frequencies:

• Channel 1 460.025 Eastside
• Channel 2 460.125 Westside
• Channel 3 460.225 Teletype
• Channel 4 460.275 Emergency channel/Intercity
• Channel 5 460.275 simplex - used for on-scene stuff
• Channel 6 460.325 Primary used by vice and sometimes teletype

Using this example you can have up to 6 officers talking at one time since you only have 6 frequencies. With trunking, you can use up to the available amount of frequencies because of staying on one frequency, you can use any of the available frequencies at any given time. If TPD has a lot of activity going on and sanitation does not, they can "use" more frequencies as needed. Here is how it works.

Instead of channels (for someone monitoring), in the trunking system you have a "group id" . The term channel will be referenced on the radio used... such as "Go to Channel 10B. A group is simply a number that is assigned to a common group of radios. Eastside is assigned a group id. Westside is assigned a group id and so on. In our example, Eastside is group 16, Westside is group 32, Teletype is group 48, and so on. We will even add more groups! When we were on UHF, we only had 6 groups (they were called channels before) but since we are now in a trunking environment we can add as many as we want!

Let's add an administration group, a general talk group, a special event group, a TAC group, a vice group and so on. So far we have now have 8 groups including the ones we have already mentioned (East,West,Teletype). So now we can have up to 8 frequencies in use out of 15. If we need more, the system will assigned more freqs as the officers in the groups start talking. As with any system, when you talk you are on 1 frequency at a given time.

Are you with me so far? If so... mush on! The City of Tallahassee is using Motorola MTS 2000 handheld radios (also some mobiles). They are 16 "channel or Radio Position" radios with up to 6 "zones". So there is a possible of having 96 channels with this radio. To make it easy to move around, each radio has many buttons and an LCD panel. Gone are the rotary knobs on the old style radios!

So we don't get too confused with the term channels, we will now call the channels on the mobiles and portables "radio positions".

Let's make a chart of the to make some more sense of this stuff! This chart below only shows the radio layout and not "Group ID's" which we will discuss down below:

Ok so now we have a pretty chart. How the heck to we monitor Special Event 10B (position 10B)??? Well with a conventional scanner you are not going to know how. You will be listening to every radio in the City of Tallahassee. The trick is to get a Trunk Tracking Scanner!

Trunk Tracking Scanners

Trunk Tracking (TT) scanners do just that. They can monitor a trunking system.

Radio shack carries several TT scanners. The Pro-2050 (which is what I use!) and the handheld Pro-90. Uniden makes the BC235 handheld and the new PC895XLT which includes computer control, Signal Strength meter and a Tone Controlled Squelch System (CTCSS or PL).

Remember up top we were talking about the control channel? The TT scanner monitors the control channel and keeps track of the Group ID's for you automatically. This is the new way to scan! Remember when we said no channels? To a scanner user.. we don't care about "channels" anymore we need to know GROUP ID'S!

What about those Group ID's?

When each radio is programmed, each Radio Position is assigned a Group ID. When PTT is pressed, all radios on the same Radio Position will hear the transmission since they are monitoring the same group. Fortunately you don't really need to know how it work... just how to monitor!

Trunk Tracking scanners are programmed with all the trunk frequencies similar to a conventional scanner. Next you activate the trunk "tracking" by pressing the Trunk Key. The scanner then monitors the control channel which keeps track of all activity. When a transmission occurs, the Group ID is displayed on the scanner digital readout. You are now monitoring 800 trunking! Each scanner will allow you to make "list" of your favorite groups to monitor (this varies for each scanner) so you can just scan those if you want. Otherwise you will see all ID's as conversations take place.

Stay Tuned...... This is work in progress!