Conventional scanning is a simple concept. You enter a radio
frequency in your scanner’s memory which is used by
someone you want to monitor. For example, the police in your
area may transmit on 460.500 MHz, the fire department on
154.445 MHz, the highway department on 37.900 MHz, etc.
So when your scanner stops on a frequency, you usually
know who it is, and more importantly, you can stop on a
channel and listen to an entire conversation. This type of
scanning is easy and fun.
As the demand for public communications has increased,
many public radio users don't have enough frequencies to
meet their needs, and this has created a serious problem.
Trunking radio systems have been implemented to solve this
problem.
In a trunked radio system the frequencies are shared among
the police and fire departments and a computer systematically
assigns available frequencies when they are needed for
communications.
Sharing of the available public service frequencies, or
trunking, allows cities, counties, or other agencies to
accommodate hundreds of users with relatively few
frequencies. Following a conversation on a trunked system
using a convertional scanner is difficult, if not impossible.
Because when there's a short break during the conversation
you're monitoring, a completely different frequency will be
assigned within the trunked system when the conversation
resumes.
If your local police, fire, and EMS agencies use a trunked
system and you want to be able to follow their
communications, you will want to purchase one of Uniden’s
Trunk Tracking Scanners.
4
What is Trunk Tracking?
