FRIENDCOM FC-302 User manual

FC-302 Data Radio
User Manual
Address: Comprehensive building, Wanyelong science and technology Park, Liyuan
Industrial Zone, Shiyan Street, Bao'an District, Shenzhen City 518108
P.R.CHINA.
Tel: [phone] [phone]
Fax: [phone]
E-mail: [email protected]
Website: http://www.friendcom.cn
SHENZHENG FRIENDCOM TECHNOLOGY DEVELOPMENT CO.,LTD

FC-302 Data Radio User Manual
Page 1
Content
1 Product Description...............................................................................................................................................2
2 Technical Specifications....................................................................................................................................... 3
3.1 Power Supply............................................................................................................................................. 5
3.2 RF Channel.................................................................................................................................................5
3.3 Data Baseband Circuit................................................................................................................................6
3.4 Voice Processing Circuit............................................................................................................................7
3.5 Side Tone Circuit....................................................................................................................................... 7
3.6 CTCSS/DCS...............................................................................................................................................8
3.7 Two-Point Balanced Modulation............................................................................................................... 8
3.8 Channel Selection Circuit.......................................................................................................................... 8
3.9 Interfaces.................................................................................................................................................... 9
4 Features............................................................................................................................................................... 15
4.1 Power Save Mode.................................................................................................................................... 15
4.2 CTCSS/DCS.............................................................................................................................................15
4.3 TX Protection...........................................................................................................................................16
4.4 Channel Spacing...................................................................................................................................... 16
4.5 The Field Detection..................................................................................................................................16
4.6 SQ(Squelch) Level...................................................................................................................................16
4.7 De-emphasis Volume...............................................................................................................................16
4.8 Sidetone....................................................................................................................................................16
4.9 Voltage Protection....................................................................................................................................16
4.10 Channel Scan..........................................................................................................................................16
4.11 Channel Select........................................................................................................................................17
5 Maintenance and Repair......................................................................................................................................17
5.1 Dimensions............................................................................................................................................ 17
5.2 Removing & Replacing the Upper Cover............................................................................................... 18
5.3 Removing & Replacing the Power Board & Modem Board & Shield Plate.......................................... 18
5.4 Removing & Replacing the Main Board................................................................................................. 19
5.5 Repairable/Replaceable Parts List........................................................................................................... 20
6 Accessories Available......................................................................................................................................... 21

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1 Product Description
FC-302 is a synthesized 5-watt FM transceiver module, which is designed for data transportation and
voice communication. For the voice communication, it can support selected pre-emphasis, squelch and audio
amplifier. The radio is PLL(Phase Lock Loop Synthesizer) /microprocessor controlled with optional GMSK,
FFSK modem board. The application of two-point modulation with good low-frequency response in the radio
also makes it a competitive choice for 1200-19200bps rate data application. Compact dimension and wide
range DC support make it flexible to use.
Features:
• CE, FCC& AS/NZS 4295: 2004 certified
• Programmable 16 channels with Dip-Switch
• Configurable power save feature
• Optional external channel configuration
• FSK, FFSK& GMSK modem option
• Frequency step 5KHz/6.25KHz
• CTCSS/DCS
• Support maximum RF data rate: 19200bps
• Fast lock time: 5ms
• SQ programmable via PC
• Pocsag Modulation
• PC programmable & Software tune & Calibration
Applications:
• Industrial telemetry & wireless remote control
• Gas and oil flow monitoring
• Electricity, water and gas utilities
• Earthquake, weather, environmental protection and urban lighting control
• Vehicle tracking and asset tracking systems
• Water monitoring, waste water management and irrigation control
• Railway, police, army automation system
• Aerial defense and fire alarm system
• Wireless Paging system

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2 Technical Specifications
General Specification
Working Frequency 450MHz～490MHz
Channel Spacing 12.5KHz/25KHz Programmable
Modulation Type F3D/F3E
Number of Channels 16
Nominal Working Voltage 12V DC
Extreme Working Voltage 9.5 V～16V DC
Storage Temperature -40℃～+80℃
Operating Temperature -30℃～+65℃
Current
Consumption
Standby ＜100mA
Transmit 5 watts RF Power ＜1.5A
Transmit 1 watt RF Power ＜1A
Lock Time
TX to RX Attack Time ＜5ms
RX to TX attack time ＜5ms
Frequency Error ＜2.5ppm
Antenna Connector BNC 50Ω
External interface DB15/DB9(optional male interface)
Transmitter Specification
RF Power 1W/2W/3W/4W/5W Programmable
Frequency
Deviation
25KHz Channel Spacing ＜5KHz
12.5KHz Channel Spacing ＜2.5KHz
Subsonic 0.5KHz
Audio
Response
25KHz Channel Spacing 300Hz～3KHz +1/-3dB
12.5KHz Channel Spacing 300Hz～2.55KHz +1/-3dB
Adjacent
Channel
Power
25KHz Channel Spacing ＜-70dBc
12.5KHz Channel Spacing ＜-65dBc
Conducted Spurious Emission
＜1GHz,＜-36dBm
＞1GHz,＜-30dBm
Modulation
Sensitivity
Voice 8~15mV
Data 80~130mV
TX SNR
25KHz Channel Spacing ＞45dB
12.5KHz Channel Spacing ＞40dB

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Receiver Specification
RX Sensitivity
(12dB SINAD)
25KHz Channel Spacing ＜-119dBm Extreme＜-115dBm
12.5KHz Channel Spacing ＜-119dBm Extreme＜-115dBm
ACP
25KHz Channel Spacing ＞70dB
12.5KHz Channel Spacing ＞60dB
Image Rejection ＞70dB
IF Rejection ＞70dB
Spurious Rejection ＞70dB
Intermodulation Suppression ＞65dB
Conducted Spurious Emission ＜-57dBm
Receiving Audio Distortion ＜5%
RX SNR
25KHz Channel Spacing ＞45dB
12.5KHz Channel Spacing ＞40dB
Audio Output Power 0.5W @ 8Ωload
3 Theory of Operation
Fig. 1 Overall Circuit Diagram

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FC-302 is comprised of three PCBs (an Mainboard PCB, a Power board and a Modem PCB). These
boards are an 18 pin female and male connector. The digital board is interfaced with external data equipment
through the 15 pin d-sub male connector, which controls the radio and data receiving and sending.
3.1 Power Supply
Fig. 2 Power Supply Diagram
Input 9V～12V will be lowered to 7.5V by DC-DC before it input to the machine. Then it divides into to
circuits through LDO and stabilizes at 5V. One circuit supplies power for RF unit and the other supplies power
for baseband unit. By adopting high-efficiency DC-DC to convert input voltage, the stabilities of all technical
features can be assured.
3.2 RF Channel
Fig. 3 RF Circuit Diagram
FC-302 receiver adopts two-stage intermediate frequency, 45.1MHz and 455KHz. When in RX mode,
the RF signal pass though Antenna Port, Low Pass Filter and RF switching circuit then finally sent to a
Low-noise Band-pass Amplifier Circuit for being magnified. The magnified RF signal and the first local
oscillator signal outputted by VCO will proceed mixing in the first mixer, then produce first intermediate
frequency 45.1MHz. The first intermediate frequency would be filtered by a 45.1MHz crystal band-pass filter.
After buffer amplification it is sent to Pin 16 of IF-PLL demodulation chip. Inside the IF-PLL demodulation
chip the signal will mix with the second local oscillator and produce second intermediate frequency 455KHz.
The 455KHz intermediate frequency will be selected , magnified, limited, and demodulated by the band-pass
filter and then transferred into a baseband signal.

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The low-noise band-pass amplifier adopts electric tuning technology，which can automatically adjust the
center frequency of band-pass filter based on working frequency, to assure a good selectivity and
anti-jamming capability.
About the transmission, the frequency synthesizer(PLL) constituted by voltage-controlled oscillator(VCO),
phase-locked loop chip and reference frequency source produce a carrier signal，which then is sent to radio
frequency power amplifier after buffer amplification. The radio frequency power amplifier finally output a 5W
carrier signal after RF on-off circuit, low pass filter and finally transferred to antenna port.
The power control of RF power amplification adopts automatic current control, by sampling the power
amplifier current，comparing with reference value，auto-adjusting to assure it would stay the same with
reference value. By this step the software programming settings of RF power can be achieved.
3.3 Data Baseband Circuit
Fig. 4 Data Baseband Circuit Diagram
The circuit mainly works on the amplification of data base band signal, filtering of FSK baseband and
shaping etc.
The data baseband processing circuit supports very low signal frequency, even the DC level and the
amplitude frequency characteristics of wide and flat to meet the high-speed data transmission. The baseband
signal join from the TFSK end and is sent to the modulation circuit after DC level shift, amplification, channel
switch and a gain adjustment circuit .
AUDIO IN offer another data/voice modulation input port, which can transfer audio (data) signals sub
3KHz, adopting AC coupling with narrow frequency response, appropriate for low-speed data modulation.
In Rx mode, the intermediate frequency demodulation chip output baseband signal. The baseband signal is
amplified and go through DC level shift, narrowband and wideband switching, then is sent to the variable
gain amplifier. After that baseband signal containing DC component is output from the RFSK terminal. The
other signal is sent to the low pass filter to select sub 3KHz audio signal (data). After controllable switch circuit,
audio(data) output from filter or data signal shaped into a square wave signal can be output directly in AUDIO
OUT, appropriate for low speed data transmission.

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3.4 Voice Processing Circuit
Fig.5 Voice Processing Block Diagram
When in TX mode, speech signal is transferred from the MIC IN to amplifier with automatic gain control
function for amplification , and then is sent to the modulator through the audio frequency pre- emphasis circuit,
a limiter circuit and low pass filter.
When in RX mode, the intermediate frequency demodulation chip output baseband signal. The baseband
signal is amplified and go through DC level shift, narrowband and wideband switching. the filter is consist of
3KHz low-pass filter and 300Hz high-pass filter, mainly used for tone and high-frequency noise filtering to
improve signal to noise ratio(SNR). Then the audio signal is output from the SPK after volume controls and
power amplifier.
3.5 Side Tone Circuit
Fig. 6 Sidetone Block Diagram
When sidetone function is enable, signal amplified by MCU will be separated. One part of signal will be

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transferred to the audio power amplifier to drive trumpet for voice. Then users can hear his own voice when
sending the voice.
3.6 CTCSS/DCS
Fig.7 CTCSS/DCS Processing Block Diagram
CTCSS/DCS encoding and decoding is completed by the MCU. When radio is in TX mode, subaudio sent
from the MCU is directly transferred to the carrier modulator-carrier modulation via second-order RC filter.
When the radio in Rx mode, baseband signal output form intermediate-frequency demodulator chip process the
audio filtering after the DC level shift and switching between wideband and narrowband. The audio filter is an
300Hz low pass filter and select sub audio signal sent to the MCU for decoding.
3.7 Two-Point Balanced Modulation
Fig.8 Two-point Balanced Modulation Diagram
Two-point balanced modulation is used when carrier is modulated by baseband signal. That is one signal
modulate reference frequency source of the frequency synthesizer, another signal modulate the VCO frequency.
Two-point modulation have characteristics of linearity and bandwidth etc. The radio two-point modulation uses
DC coupling mode, making modulation signal low end frequency response smoother.
3.8 Channel Selection Circuit
Fig.9 Channel Selection Diagram
The radio’s 16 channels can be select by inner dip switch (4 bits). MCU reads the status of the switch to
select wanted channel by changing dip switch(4 bits). Besides hardware control, software control is also
available when banning dip switch.

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3.9 Interfaces
Mainboard interface：
Fig.10 Mainboard Interface Description
There are two external interfaces in mainboard. One is J106 and connected to the Power board,
transferring available I/O signal to the user through the Power. The other is J100 and connected with modem,
customers can develop appropriate modem according to specific requirement.
Power Board (PWR):