Conventional Scanning; Simplex Operation - Uniden BC75XLT Owner's Manual

Conventional Scanning

Conventional scanning is a relatively simple concept. Each
group of users in a conventional system is assigned a single
frequency (for simplex systems) or two frequencies (for
repeater systems). Any time one of them transmits, their
transmission always goes out on the same frequency. Up
until the late 1980's this was the primary way that radio
systems operated.
Even today, there are many 2-way radio users who operate
using a conventional system:
• Aircraft
• Amateur radio
• FrS/GMrS users
• Broadcast AM/FM/TV stations
• Many business radio users
When you want to store a conventional system, all you need
to know are the frequencies they operate on. When you
are scanning a conventional system, the scanner stops very
briefly on each channel to see if there is activity. if there isn't,
the scanner quickly moves to the next channel. if there is,
then the scanner pauses on the transmission until it is over.

Simplex Operation

Simplex systems use a single frequency for both transmit
and receive. Most radios using this type of operation
are limited to line-of-sight operation. This type of radio
is frequently used at construction job sites and with
inexpensive consumer radios such as GMrS/FrS radios. The
range is typically 1-8 miles, depending upon the terrain and
many other factors.
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