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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 ) × Step )

Base + ( (759 – Offset ) × 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 Base_n = Base_n + ( Offset_n+1 – 1 – Offset_n ) × Step_n

Upper Base_n = Base_n + ( Offset_n+1 – 1 – Offset_n ) × Step_n

Where:

Base_n is the lower base frequency for the entry.
Offset_n+1 is the Offset for the next band plan (for the last table, use 760).
Offset_n is the offset for this band plan.
Step_n 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:

For entry A:
Upper Base_A	=	Base_A +	( Offset_B – 1	– Offset_A )	× Step_A
Upper Base_A	=	155.415 MHz +	(436 – 1	– 380)	× 15kHz
Upper Base_A	=	155.415 MHz +	55		× 0.015 MHz
Upper Base_A	=	155.415 MHz +	0.825 MHz
Upper Base_A	=	156.240 MHz

For entry B:
Upper Base_B	=	Base_B +	( Offset_C – 1	– Offset_B )	× Step_B
Upper Base_B	=	157.200 MHz +	(454 – 1	– 436)	× 12.5 kHz
Upper Base_B	=	157.200 MHz +	17		× 0.0125 MHz
Upper Base_B	=	157.200 MHz +	0.2125 MHz
Upper Base_B	=	157.4125 MHz

For entry C:
Upper Base_C	=	Base_C +	( Offset_C+1 – 1	– Offset_C )	× Step_C
Upper Base_C	=	157.470 MHz +	(760 – 1	– 454)	× 15 kHz
Upper Base_C	=	157.470 MHz +	305		× 0.015 MHz
Upper Base_C	=	157.470 MHz +	4.575 MHz
Upper Base_C	=	162.045 MHz

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

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

Topic revision: r7 - 01 Sep 2009 - 15:42:58 - PaulOpitz

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