Operating instructions

Operation DMH Series VHF Radio
BK RADIO Page 3-5
Select a channel by turning the Channel Selector knob. When the unstopped channel
selector is rotated past the highest (16
th
) channel, the radio will emit a beep and
remain on the highest channel. When rotated past the lowest (1
st
) channel, the radio
will emit a beep and remain on the lowest channel.
The display can show channel numbers (Numeric Mode), channel labels
(Alphanumeric Mode), or receive and transmit frequencies. The Display Mode and
Channel Labels are programmed by the technician along with Group Labels (if
applicable) and channel frequencies. The display shows slightly different indications
during Channel Scan and Priority Scan operation in alphanumeric and numeric
modes.
3.5.2 TRANSMIT
Press the PTT (Push-To-Talk) switch on the microphone. The TX annunciator
appears on the display and the red Transmit indicator illuminates while the PTT is
pressed. Talk in a normal voice with the microphone approximately one to two inches
from your mouth. Release the PTT switch to stop transmitting.
If the TX annunciator does not appear and a tone is heard, you are on a receive-only
channel or the channel is busy (if Busy Channel Lockout is enabled). Turn the
Channel Selector knob to an authorized transmit channel or wait until the channel is
clear (if Busy Channel Lockout is installed).
If the length of your transmission exceeds the preset Time-Out Timer setting, the
transmitter automatically shuts off and a tone sounds. To continue the transmission,
release the PTT switch, and then press it again and continue talking.
3.6 CHANNEL GUARD OPERATION
Channel Guard allows one radio or group of radios to be selectively called within a
system. If the radio has been programmed with Channel Guard, use the following
receive and transmit instructions.
3.6.1 ANALOG SQUELCH CONTROL
Sub-audible signaling (CTCSS/CDCSS) is used to allow a group of radios to be
selectively called in a system. Programming the receive guard equal to zero allows
for Carrier Squelch operation, where the radio will unmute whenever a carrier is
detected.
3.6.2 APCO PROJECT 25 SQUELCH CONTROL
Network Access Codes (NACs) provide the digital equivalent of analog sub-audible
signaling (CTCSS/CDCSS) allowing a group of radios to be selectively called within a
system.
Users in the same area (using the same NAC) can be further divided into Talk
Groups, with each group having its own Talk Group ID (TGID). Group Calls are
made by designating both the users’ NAC and TGID.
Each radio also has an individual P25 unit ID. A Unit-to-Unit call contains the
addressee’s NAC, and uses the addressee’s P25 unit ID instead of the TGID.