Terms and Definitions, Frequency, Mobile Extender

Introduction

Terms and Definitions

Frequency	Radio signals are sent as waves through the
	air. These waves move up and down. A
	frequency is the number of times in a certain
	time period, usually a second, that these
	waves move all the way up and all the way
	down and back to all the way up. For example:
	123.44 kHz means that the waves are moving
	all the way up and all the way down and back
	all the way up again 123,440 times each
	second.
Mobile Extender	When highway patrol officers step away from
	their cars, signals from the patrol car are sent
	to their portable radios via a mobile extender.
	The mobile extender is a transmitter/receiver
	that receives the signal from the station and
	transmits it to the portable radio on a different,
	but lower, frequency.
Scanning	Scanning is the process by which your
	scanning radio looks for “activity” in the
	channels it is programmed to look at. The
	scanner checks each frequency for the
	presence of a signal, and when it finds a
	frequency with a signal, for example someone
	talking on it, it stops, allowing you to listen to
	the signal. The BCT-10’s Highway Patrol Alert
	System also looks for activity on mobile
	extender frequencies. When the BCT-10
	detects the presence of a signal on one of
	these frequencies, it will trigger an audio and
	visual alarm.