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Understanding Scanning
17
What is Searching?
What is CTCSS/DCS?
The UBCD396T can search 9 service search ranges
and up to 10 bands together to find active
frequencies. This is different from scanning because
you are searching for frequencies that have not been
programmed into the scanner. When you select
frequency bands to search, the scanner searches for
any active frequency within the lower and upper limits
you specify. When the scanner finds an active
frequency, it stops on that frequency as long as the
transmission lasts. If you think the frequency is
interesting, you can program it into the scanner’s
memory. If not, you can continue to search.
Your scanner can monitor systems using a
Continuous Tone Coded Squelch System (CTCSS)
and Digital Coded Squelch (DCS) system, which allow
squelch to open only when the tone you have
programmed with a specific frequency is received
along with a transmission.
CTCSS and DCS are subaudible tone signaling
systems sometimes referred to as PL or DPL
(Motorola’s trademarked terms for Private Line and
Digital Private Line respectively). CTCSS and DCS
are used only for FM signals and are usually
associated with both amateur and commercial
two-way frequencies. These systems make use of a
special subaudible tone that accompanies a
transmitted signal.
CTCSS and DCS are used for many purposes. In
many cases, CTCSS and DCS are used to restrict
access to a commercial repeater, so that only those
units which transmit the correct tone along with their
signal can “talk” to the repeater.