User's Manual

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.