# 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:

• Base = the lower base frequency listed in RRDB.
• Offset = the offset for this entry.
• Step = the step for this entry in MHz (convert from kHz to MHz by moving the decimal point three places to the left).
For sites with multiple band plans:
 Upper Basen = Basen + ( Offsetn+1 – 1 – Offsetn ) x Stepn

Where:

• Basen is the lower base frequency for the entry.
• Offsetn+1 is the Offset for the next band plan (for the last table, use 760).
• Offsetn is the offset for this band plan.
• Stepn is the step for this band in MHz (convert from kHz to MHz by moving the decimal point three places to the left).
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:

 156.240 MHz 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 =

 157.4125 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 =

 162.045 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 =

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