可燃气体报警器外文翻译文献
(文档含中英文对照即英文原文和中文翻译)
原文：
Design of Combustible Gas Detection system using Wireless
Keywords:TGS813, AT89S52, DS18B20, nRF905, TC35i
Abstract.The detection device of combustible gas are designed in the presented work,using wireless transceiver and GSM network.The system realize the wireless transmission of the gas concentration,and also can send alarm information to user’s mobile when an exception occurs.
The system consists of two parts: a master and slave. The function of the slave is to collect data,
process data and transffer the data to the master.The taskof the master is to receive data and
display it by LED.
design翻译The signal acquisition is completed by sensor TGS813 and A/D converter TLC2543. The
wireless transmission is achieved through wireless transceiver nRF905. Since the accuracy of the
sensor is affected by the environment,using DS18B20 to achieve temperature compensation.
And with wireless communication module TC35i and GSM network platform, we can send the
alarm information t o user’s mobile promptly.
Introduction
Gas detection is widely used in petroleum, chemical, metallurgy, family, shopping malls,
gas stations and other places. Currently, how to monitor the hazardous gas fast and accurately
are the important issues. Although the gas detection technology is relatively mature, but most
products has many shortcomings, such as single function, operating complex, bulky, expensive
and low sensitivity. Wireless communication technology applied to the gas monitoring field, can
resolve the problem of remote monitoring in special environment, such as high temperature, low temperature, toxic gas.and unable to wiring .
In the presented work, the combustible gas detectoris fully functional (with wireless transceiver), simple, small size, low cost, and has high sensitivity. The equipment can greatly
improve the system's detection capability and accuracy with temperature compensation algorithm, and also can send alarm information to the user's mobile phone promptly through the
GSM network.
System design
The system consists of two parts as shown in Figure 1.
Fig. 1 Overall system block diagram
The slave part mainly complete data collection and wireless transmission. The master part mainly complete receiving data, displaying and sending alarm message.
The signal of gas concentration is collected by combustible gas sensor which generates a weak electrical signal. The signal can be amplified and stabilized by conditioning circuit. And then A/D circuit converts the analog signal to digital signal which microcontroller can process. In order to improve the
measurement accuracy, and reduce the impact of temperature, design a temperature compensation circuit to collect tempreture data. AT89S52 process the collected data and send data to the master by wireless transceiver.
The master receives the data and displays it by LED. And if the gas concentration being abnormal,the system will drive speaker for an alarm signal and use TC35i module to send alarm information to user’s mobile.
Hardware design
Signal acquisition and conditioning circuit. Figure 2 shows data acquisition circuit. TGS813 is a Gas s
ensing resistive sensor. The conductivity of TGS813 is influenced by the concentration of combustible gases in air, the greater the concentration, the higher conductivity. In system R0, R9, R10 and RS (in
TGS813) form a bridge circuit to convert resistance to voltage signal. Operational amplifier A connected as a voltage follower with resistors R7 and regulator D1 make up the voltage regulator circuit to supply power for the bridge. In order to the voltage adapt to the A/D converter, the voltage is amplified by opamp B, and the magnification can be adjusted through resistor R11.
Fig. 2 Gas concentration signal acquisition circuit
Fig. 3 Temperature compensation circuit
Temperature compensation circuit. The resistance of Rs is greatly affected by temperature. In order to improve system accuracy, the results must be temperature compensated or temperature correction.In system, using temperature sensor DS1820 to collect temperature signal, and using software method for temperature correction.
Wireless transmission module.Wireless transceiver is achieved by a single-chip RF transceiver nRF905. MCU and nRF905 realize data and commands interaction
through the SPI interface.The typical application schematic is shown in Figure 4. The antenna part is 50Ω single-ended antenna.The communication frequency is 433MHz, and operating voltage is 3.3V. The value of resistors,capacitors and inductor is determined by the datasheet of nRF905.
GSM short message unit.The interface circuit of TC35i and MCU is shown in Figure 5. The
communication between MCU and TC35i is via serial, and the rate is 9600bps. Communicationsmode is 8-bit asynchronous with a start bit, 8 data bits, and 1 stop bit. But the serial input of TC35i requires CMOS level, and serial output of 89C52 requires TTL level. In order to achieve the voltage conversion the system use the way of resistors sharing voltage.
Fig. 4 nRF905 Application Schematic
Fig. 5 TC35i and MCU interface circuit
Software Design
The software system includes data acquisition module, temperature compensation module, and wireless transceiver module
Wireless sending program. NRF905 data sending process is as follows:
1) When having data to send, the microcontroller send the receiver's address and the data to nRF90
5 chronologically by the SPI interface.Then placed the data to be transmitted into TxBuf register, send WTP command to write the data to TX-Payload register, and send WTA command to write TX address to the TX-Address register.
2) The microcontroller set TRX_CE=1 and TX_EN=1 to stimulate nRF905 ShockBurstTM sending mode. When data transmission completed, the data ready pin is set high;
3) Beacause of AUTO_RETRAN being high, the data of nRF905 is constantly re-issued until
TRX_CE=0.
4) when TRX_CE pin is set low, means the data transmission completed and nRF905 enter idlemode.
Wireless receiving program. NRF905 data receiving process is as follows:
1)When TRX_CE = 1 and TX_EN = 0, nRF905 enters ShockBurstTM receive mode checking
constantly and waiting for receiving data.
2)When nRF905 detect the carrier having same frequency band, the carrier detect
pin will be set high.
3)When nRF905 receive a matched address, the address matches pin will be set
high.
4) When packet correctly received, the word head, address and CRC bits will automatically be
removed, and the data ready pin will be set high.
5) MCU set TRX_CE to "0", and nRF905 enter to idle mode.
6) When all the data received, nRF905 set data ready pin and address matching pin to "0", and
nRF905 turn to shutdown mode or ShockBurstTM transmitmode and receive mode.
Fig.6 Wireless data transmission flow chart

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