User's Manual

Shenzhen Friendcom Technology Development Co., Ltd.
7
3.2 Interface for data transmission
As to FC-302 with internal modem, the pin definition is shown in Table 3.
Table 3
Pin Name Pin No. Decription 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;
nominal +12V
BUSY
6
Logical level output to indicated whether
there is 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
AUDIO_IN is effective only when PIN 7(MIC)
is vacant or with +5V high level. 3KHz LPF
filter existed in audio channel.
GND
10
Power ground for modem
RXD
（Modem）
11
The serial data is input to modem through
this pin. Default is RS232.
The hardware is one of RS232, RS485 or
TTL/5V when delivery.
EX_PTT
12
Data transmision control. Actice at low
level
EX_PTT is valid with installed modems below:
FC-302-GMSK,
TXD
（
Modem
）
13
Serial data is output from modem via this
pin. Default is RS232.
The hardware is one of RS232, RS485 or
TTL/5V when delivery.
CD_OUT
14
Logical level output to indicated whether
a carrier or not. Low lever = carrier , high
level=no carrier.
Note: do not change the level to low unless the
internal modem needs.
NC
15
3.3 Modem Option for Data Communication
GMSK
high speed modem are applied to the FC-302 data radio to increase capability for data
application. The goal of an internal modem is to improve the efficiency for data transmission and provide
maximum flexibility for user application.