3.1 Interface for Voice Transmission
Standard DB15 is only used for voice transmission.
Pin 10
～
Pin15 on DB15 is used for extending the optional function of
the channel meanwhile bring out the hardware serial port. The pin definition is shown in Table 2.
Table 2
Pin Name
Pin No. on
DB15
Description
Remark
AUDIO_IN
(MOD IN)
1
Audio
input.
3Khz
LPF;
Modulation
sensitivity is 100mW
AUDIO_IN is effective only when
PIN 7(MIC) is vacant or with +5V
high level. 3KHz LPF filter existed
in audio channel.
AUDIO_OUT
(AF OUT)
2
Audio output; 3Khz LPF; Output level at
60% frequency deviation is 100
±
30mV. This
line has an internal pull-up resistor to +5V.
PTT
3
TX control
，
active low, only when PTT is
active AUDIO_IN and MIC IN are effective.
This line has an internal pull-up to 5V.
GND
4
Ground
B+(9.6
～
16V
DC)
5
Positive pole input from DC power; +12V
BUSY
6
Logical level output to indicated whether a
carrier or not. Low lever = carrier , high
level=no carrier. This line has a pull-up to
+5V.
Also able to work as simulated
serial and data transmission port.
MIC IN
7
Microphones input.
Can directly connect to electrets
MIC, the DC voltage of this pin
should lower than 3.5V, then MIC
transmission can be activated.
SWITCH
8
Control output, 5V high level output when
active
Also able to work as simulated
serial and data transmission port.
SPK
9
Audio output from the audio amplifier, @ 8Ω
SPK is effective when Pin 7
connect to MIC or GND,
（
MIC PIN
power than 3.5V
TXD
（
Radio
）
10
The serial data is output from this pin, used
for radio parameter setting
，
5V TTL
Data is output from radio.
RXD
（
Radio
）
11
The serial data is input to this pin, used for
radio parameter setting
，
5V TTL
Data is input into radio
CH1
12
Select channel by Dip switch; the low bit of
4-bit binary code.
Available when channel control
mode is programmed as “by Dip
switch”
CH2
13
Select channel by Dip switch; the second bit
of 4-bit binary code.
CH3
14
Select channel by Dip switch; the third bit of
4-bit binary code.
CH4
15
Select channel by Dip switch; the forth bit of
4-bit binary code.
