Calculating upper base frequencies

Custom Band Plans (800 Custom, VHF, UHF) require that you enter both a lower and an upper base frequency value. Here's how to determine these values.

The Easy Way

Use this spreadsheet to calculate the values for you: CustomBandPlanCalculator.xls

The Hard Way

The Lower Base Frequency (or Base ) is always the base frequency as provided in the RRDB. The Upper Base Frequency is calculated from the following formulas:

For sites with a single band plan:
Base + ( (759 – Offset ) x Step )

Where:

For sites with multiple band plans:
Upper Basen = Basen + ( Offsetn+1 – 1 – Offsetn ) x Stepn

Where:

For example:

Custom Frequency Table

Entry Base Spacing Offset
A 155.4150 15.0 380
B 157.2000 12.5 436
C 157.4700 15.0 454

Plugging these values into our formula, we get:

For entry A:
Upper BaseA = BaseA + ( OffsetB – 1 OffsetA ) x StepA
Upper BaseA = 155.415 MHz + (436 – 1 – 380) x 15kHz
Upper BaseA = 155.415 MHz + 55 x 0.015 MHz
Upper BaseA = 155.415 MHz + 0.825 MHz
Upper BaseA = 156.240 MHz

For entry B:
Upper BaseB = BaseB + ( OffsetC – 1 OffsetB ) x StepB
Upper BaseB = 157.200 MHz + (454 – 1 – 436) x 12.5 kHz
Upper BaseB = 157.200 MHz + 17 x 0.0125 MHz
Upper BaseB = 157.200 MHz + 0.2125 MHz
Upper BaseB = 157.4125 MHz

For entry C:
Upper BaseC = BaseC + ( OffsetC+1 – 1 OffsetC ) x StepC
Upper BaseC = 157.470 MHz + (760 – 1 – 454) x 15 kHz
Upper BaseC = 157.470 MHz + 305 x 0.015 MHz
Upper BaseC = 157.470 MHz + 4.575 MHz
Upper BaseC = 162.045 MHz

This page applies to the following scanner(s): BCD996XT BCT15X BCD396XT BC346XT BC346XTC Users Guide