User manual

2.3.2.1 Motorola VHF/UHF systems:
Explanation of base/step/offset parameters:
For a type 2 VHF or type 2 UHF you must program base/step/offset
parameters.
For properly tracking a type 2 VHF/UHF system, the scanner needs channel
number information. The tracking process is controlled by sending channel
numbers instead of frequencies. Once the scanner knows one combination of
frequency and channel number it will track the system because it can calculate
all other frequencies using the step setting and the channel number it receives
from the traffic channel.
You must know at least one frequency used in the trunk systems AND the
channel number assigned to that frequency.
The step is normally predefined for the frequency range.
Example:
If the system you want to program uses a frequency 425.250 (step 25 kHz)
and the channel number assigned to that frequency is 402 then you must
program:
Base: 425.250
Step: 25
Offset: 402
Because you know the step and channel number you can also use different
settings, in the table below all given examples of base/step/offset will have the
same effect:
Example 1 Example 2 Example 3 Example 4
Frequency 425.250 425.200 420.000 430.200
Step 25 25 25 25
Offset 402 400 380 600
The offset channel has a range of 380-600.
ARC330 Software User Manual 102- 16