Busy Channel Lockout; Call Guard Squelch - E.F. Johnson Company 51 Series Preliminary Operation Manual

CONVENTIONAL FEATURES

Busy Channel Lockout

The Busy Channel Lockout feature (also called Transmit Disable On
Busy) automatically disables the transmitter if the channel is busy when
the PTT switch is pressed. When a busy condition is detected by this
feature, the transmitter is disabled, "BUSY" is indicated in the display,
and a tone similar to a standard telephone busy tone sounds until the PTT
switch is released. The transceiver can be programmed to operate in one
of the following modes on each channel:
Off - The transmitter keys even if the channel is busy.
Noise - The transmitter is disabled if any signal is detected on the
channel.
Tone - The transmitter is disabled if the detected squelch coding is not
correct.
If busy override is permitted by programming, it is possible to
transmit even when the transmitter is disabled by this feature. Simply
release the PTT switch and then quickly press it again.

Call Guard Squelch

General
Call Guard
programmed on conventional analog channels. This feature eliminates
distracting messages intended for others using the channel by using a
subaudible tone or digital code to control the squelch. This tone or code is
unique to a user or talk group on that channel. It is transmitted by the
mobile placing a call, and if Call Guard squelch is programmed in the
mobile receiving the call, it must detect the correct tone or code to
receive the call.
Call Guard Squelch Enable/Disable
To disable Call Guard (Selective) squelch so that all messages on the
selected or scanned channels are heard, press the Normal/Selective option
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squelch (also called CTCSS/DCS signaling) may be