User's Manual

20-527 Owner’s Manual Draft
Page 13 of 60
FM Mode
The FM mode sets the scanner to receive transmissions using frequency modulation (FM), used for most
public safety transmissions, as well as broadcast, business, and amateur radio transmissions. When the
scanner receives a transmission on a channel set to the FM mode, it always stops on the transmission.
CTCSS Mode (CT)
CTCSS mode sets the scanner to receive transmissions using frequency modulation (FM) with
Continuous Tone Coded Squelch System (CTCSS) subaudible tone codes. CTCSS allows multiple users
to share a single radio frequency without hearing each other’s transmissions. In your PRO-97 scanner,
the CTCSS feature can be used to block the reception of transmissions on shared channel to only those
that use the CTCSS mode also features a Code Search setting that allows you to instantly display and
store unknown codes into the channel memory. CTCSS tones can sometimes be heard as a low “hum” in
the background of a voice transmission. Many systems that use CTCSS transmit a special “turn off code”
at the end of each transmission. The turn off code causes a properly equipped receiver to mute before
the transmission ends, eliminating the “squelch tail” burst of noise the commonly occurs when the signal
is lost. CTCSS turn off code performance can be affected by weak signals.
DCS Mode (DC)
DCS mode sets the scanner to receive transmissions using frequency modulation (FM) with Digital
Coded Squelch (DCS) subaudible data signaling. DCS is very similar to CTCSS, except that a digital
code is transmitted instead of an audio tone. Like CTCSS, DCS allows multiple users to share a single
radio frequency without hearing each other’s transmissions. In your PRO-97 scanner, the DCS feature
can be used to block the reception of transmissions on a shared channel to only those that use the DCS
tone that you have specified. DCS mode also features a Code Search setting that allows you to instantly
display and store unknown codes into the channel memory. DCS data can sometimes be heard as a low
“purring” sound in the background of a voice transmission. Some DCS systems transmit a special “turn
off code” at the end of each transmission. The turn off code causes a properly equipped receiver to mute
before the transmission ends, eliminating the “squelch tail” burst of noise the commonly occurs when the
signal is lost.
Motorola Mode
You can set your scanner so it decodes the talk group IDs used with Motorola trunking systems. This
setting is called the Motorola mode.
Motorola systems are trunking systems used primarily by business and public safety groups to efficiently
allocate a small number of frequencies (as few as five) to many groups of users (as many as several
thousand). To do this, each group of users in the system is assigned to a specific talk group. For example,