E F Johnson Company 2425M70 Benutzerhandbuch

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6-3
Conventional Features
6.3
Busy Channel Lockout
The Busy Channel Lockout (also called Transmit Disable on Busy) feature automatically 
disables the transmitter if the channel is busy when the PTT switch is pressed. When the 
transmitter is disabled by this feature, “BUSY” is displayed, a busy tone sounds, and the 
transmitter is disabled.
The Busy Channel Lockout feature can be programmed to operate as follows. Each 
conventional channel can be programmed differently.
“Off” - Busy channel lockout is disabled and the transmitter keys even if the channel is 
busy.
“Noise” - If a carrier is detected on the channel, the transmitter is disabled when the 
PTT switch is pressed.
“Tone (NAC)” - If an incorrect Call Guard (CTCSS/DCS) or P25 NAC code (see 
Section 6.13.3) is detected, the transmitter is disabled when the PTT switch is pressed. 
An incorrect code is any code other than the one programmed for the current channel.
“Status” - Indicated status of the radio as seen from the repeater. (If the status shows 
Busy, then the mobile is transmitting.)
If Busy Channel Override is permitted by programming, it is possible to transmit even 
when the transmitter is disabled by this feature. Release the PTT switch and then quickly 
press it again within one second.
6.4
Call Guard Squelch
Tone or digital Call Guard squelch (also called CTCSS/DCS signaling) can be 
programmed on each conventional analog transmit and receive channel in any order 
desired. The reverse burst and turn-off code are always transmitted and also detected on 
channels programmed with Call Guard squelch.
The Call Guard squelch feature eliminates distracting messages intended for others using 
the channel. This is done by using a subaudible tone or digital code to control the squelch. 
This tone or code is unique to a user or a group on that channel. This tone or code is 
transmitted with the voice signal but is not heard because it is in the subaudible range and 
is attenuated by a filter. Call Guard squelch must be used in both the transmitting and 
receiving radio to be functional.
Draft 4/29/2014