Conventional Scanning; Simplex Operation - Uniden BC125AT Owner's Manual

tone with a signal, the scanner's squelch remains closed and you
hear nothing.
Refer to the Reference section of this manual for tables showing
the available CTCSS frequencies and DCS codes.

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
• Many business radio users
When you want to store a conventional system, all you need
to know is 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
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