Here is more information about Trunked Radio Systems than you really need to know, but didn't know to ask! This is stuff that will increase your enjoyment monitoring Trunked Systems.

Math for Trunktracking:

Why do I need to know math to use a Trunktracker? Well, all Talkgroups are identified via a mathmatical format. There are a couple rules you need to know first:

1) How, why and when to convert Hex numbers to Decimal and back. What and Why is Binary?

We all use Decimal (otherwise known as Base 10 since it uses 10 characters, 0 thru 9) in our everyday life. We have 10 cents to a dime, 10 dimes to a dollar and so on. Hexadecimal (or just plain Hex) is a way to express numbers of up to 15 with a single character. This is also called "Base 16" . Hex uses 0 thru 9, and the A, B, C, D, E, and F. A in Hex equals 10 is Decimal. This is popular to use in memory and computer based applications (like Trunktracking) since a larger number can be designated with less digits, thus saving prescoous memory.

A Decimal number of 3585 would be designated as E01 in Hex, saving an entire digit. Back when trunking systems were being developed this was very important since memory was extremely expensive. To maintain backwards compatibility these protocols were retained.

Binary is on the other end of the numeric spectrum. Binary (Base 2) is a way of expressing the simplist of numeric values, with only 2 characters (0 and 1) This was used in early computers and devices due to the simplicity of using 0 and 1 to indicate Off and On. To indicate a number like 1230 in Binary it would be 10011001110. Binary is the most basic of the numerical expression protocols. We use Binary to derive AFS numbers for EDACS systems.

Are there "Blocks" in a Type II system?

Yes! While most Trunktrackers equate Blocks with Type I or IIi and Hybrid systems, even the newer Type II systems use Block assignments. While most of them really don't affect Trunktracking sometimes it does. Some ASTRO systems have some blocks reserved for Analog communications and others reserved for Digital.

So, if you see a Talkgroup of 57376 it will be in Block 7, Talkgroup 48 is in Block 0. This can come in real handy when trying to figure out a Type IIi or Hybrid fleetmap.

What is the "Magic Number"?

8192! Trunked systems typically have 8 blocks, numbered 0 thru 7. Each block in a Type I system is defined by a Size Code that allows a "Magic Number" of 8192 for each block. If you multiply the number of "Fleets", "Subfleets" and "ID's" used within a block together you should get 8192. If you don't get 8192 for a single block then one of the numbers is incorrect.

Here is a table with the Uniden and Motorola Size Codes, extrapolated from Page 80 of the BC780XLT Manual: