command (AVT_OFF) using the PC because the TX switch then activates a
sequential function of capturing and transmitting the data.
.
e. Speaker volume adjustment
Adjustment for the internal speaker output level (or the external speaker output level
when one is connected).
f. MODE LED (Operation Mode LED)
Indicates the current operation mode:
Illuminated green ------------------------- Digital voice mode
Illuminated red --------------------------- Analogue voice mode
Illuminated orange------------------------ Data communication mode
Not illuminated ---------------------------- Digital image communication mode
g. CHANNEL switch
Select preloaded encryption code.
(Refer to: Channel Switch Setting on page 15 for details.)
h. OVER-LED
Lit when the microphone input is overloaded (too high).
A proper microphone input level will cause the LED to flash from time to time
when speaking into the microphone at a normal level.
The microphone level can be adjusted with the microphone level controller.
(Refer to: Level Adjustment on page 12 for details.)
In addition, the OVER-LED operates in receive mode as an input level indicator:
To set the optimum level of audio from the transceiver (crucial for good decoding of
digital signals), the OVER-LED operates as an input level indicator in receive mode in
the following ways:
Operation of input level indicator (transceiver squelch control fully open):
Input level indicator flashes whilst receiving Input level is too low
Input level indicator extinguished Input level is optimally set
Input level indicator is solidly lit Input level is too high
NB: When the squelch is closed on the transceiver the OVER–LED will flash
continuously indicating that no signal is being fed to the ARD9900.
i. Mode switch
Selects the Digital voice mode [10101] or the Analogue voice mode [~].
When the Analogue voice mode [~] is selected, ordinary analogue voice
communications will be made.
In the receive mode however, the ARD9900 will automatically detect the
mode of the incoming signal and decode signals accordingly.
The LED indicates the respective operation mode.
j. Microphone connector
Connect the supplied microphone to this connector.
Below are the pin assignments of the connector:
1. SPEAKER OUTPUT -- Monitor output signal available at this pin.
2. BIAS ---------------------- Power source for an electret condenser type of
microphone. (5V DC through 2.2K Ohm resistor).
3. GND ---------------------- Chassis ground.
4. TX-------------------------- Taking this pin to the ground will enable the transmit mode;
the same as operating the TX switch on the front panel.
5. D/A ------------------------ Taking this pin to the ground will force the unit into the
digital voice communication mode. When this pin is left
open, the operation mode will be set by the mode switch
on the front panel.
6. MIC PTT ----------------- PTT (Push To Talk) input.
