Trunking Tables - Looking for explanation

Status
Not open for further replies.

bneilson

Member
Premium Subscriber
Joined
Aug 2, 2004
Messages
874
Location
South Jordan, Utah
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...

HTML:
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

Forums Veteran
Super Moderator
Joined
Dec 16, 2000
Messages
7,501
Location
Sitting in an airport somewhere
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

Member
Premium Subscriber
Joined
Aug 2, 2004
Messages
874
Location
South Jordan, Utah
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

Forums Veteran
Super Moderator
Joined
Dec 16, 2000
Messages
7,501
Location
Sitting in an airport somewhere
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.
 
Status
Not open for further replies.
Top