Trunking Tables - Looking for explanation

[bneilson]

Hello,

I am looking for help understanding Trunking Tables.

As my local system is being rebanded (2 sites done, 39 to go) I am working with my GRE scanner to enter the custom Trunking Tables. There is another thread that covers teh exact values, but I would like to understand what they mean.

The table below is what I would like clarification on...

ChLO  ChHI  Step      Offset   Base
440    559    25.000   440      851.025000
000    719    25.000    0       851.012500
720    759    25.000    0       848.000000
815    831    25.000    0       846.625000
958    958    25.000   958      868.975000
961   1022    25.000    0       843.400000

 

[WayneH]

First, when a channel identifier is received it evaluates each range from the top and then down.

> 440 559 25.000 440 851.025000
If the radio sees anything between 440 and 559 use a base of 851.025 with spacing of 25.0kHz.

> 000 719 25.000 0 851.012500
Since the top range takes priority anything that doesn't fit within 440-559 (i.e., 000-439 and 560-719) will use these base and spacing values.

> 720 759 25.000 0 848.000000
> 815 831 25.000 0 846.625000
> 958 958 25.000 958 868.975000
> 961 1022 25.000 0 843.400000
The rest of these are used to calculate for freqs in the 866-869MHz range.

Make sense? It's pretty easy once you get the hang of it.

 

[bneilson]

Thanks for the response...

So is the 440, 559, 000 & 719 the LCN for the frequency?

You said "channel identifier" but I am not sure if that is the same as the LCN or not.

 

[WayneH]

The control channel sends out a hex code to represent a frequency. It's a little different than what's typically called an LCN but for simplicity's sake LCN will work fine. Since the calculations used to turn the code in to a frequency vary based on the range of numbers you need complicated tables like these to filter out the ranges and calculate respectively.