外文文献

The Design and Implementation of the Greenhouse

Monitoring System Based on GSM and RF

Technologies

Zhao Xiaoyan, Zheng Xiangyang, Duan Chen, Chen Zhaohui, Sang Shangming, Zhang Zhaohui

School of Automation and Electrical Engineering University of Science and Technology Beijing

Beijing, P.R. China

zhengxiangyang19880924@http://wendang.chazidian.com

Abstract- According to the characteristics of small and medium-sized greenhouse environmental monitoring, this paper proposes a solution to remote greenhouse environmental monitoring which is based on GSM technology and RF. The system constitutes the regional environmental information monitoring network and close communication platform based on radio frequency. Combined with the remote communication technology based on GSM networks, the system implements small and medium-sized greenhouse environmental monitoring. Using ATmega16A, low-power chip PTR4000 and Huawei wireless module GTM900-C to design monitoring nodes and sink nodes of the system, the paper gives the system's hardware structure and software workflow chart. It shows that the system is stable, reliable, and it’s able to achieve real-time monitoring of greenhouse environment.

Keywords-RF; sink node; wireless communication; greenhouse environmental monitoring; wireless sensor network

I. INTRODUCTION

In recent years, with the rapid development of the greenhouse industry, the greenhouse environment control technology is of higher requirements because of how to obtain accurate and reliable information, as described by [1-2]. In China, most of existing greenhouse control systems uses wired communication, which inevitably faces with wiring problem. The wiring problem includes mass construction, high cost, installation and maintenance difficulties and that a broken node is likely to cause the entire system out of work. Using wireless communication is absolutely the best solution to these problems. The wireless communication does not require wiring, it’s low cost and easy to maintain and you can also increase or decrease the measurement node arbitrarily. Thus, it has good application prospects.

Through literature review, it is found that some domestic scholars utilized wireless sensor network technology in [3-4]; while some scholars used microprocessors with Zigbee technology and multi-sensor fusion technology to design greenhouse monitoring sensor nodes, as in [5]; And some scholars utilized interventional Internet or Intranet way to achieve remote monitoring in [6]; Ref.[2] presented there were also some scholars who used GSM technology

This work is supported by the Fundamental Research Funds for the Central Universities (No. FRF-AS-09-006B); Beijing Key Discipline Development Program (No. XK100080537).

combined with wireless sensor network technology to design greenhouse environment monitoring system. These projects are relatively good designs, but their hardware designs are complex and of high cost, especially in small greenhouse monitoring applications, the cost performance is not high. In view of this, I integrate GSM wireless communication technology and radio frequency (RF) technology, and make the use of the existing GSM network terminal - GSM module for remote data transmission application conditions merging with the RF technology. Eventually, I put forward a cost-effective solution to small and medium-sized greenhouse monitoring. The system based on RF technology constitutes a regional environmental information monitoring network and combined with GSM remote communication technology, realizes the remote monitoring of small greenhouse environment successfully. Experimental results show that this system is particularly suitable for data acquisition system with short distances and requiring high reliability.

II. SYSTEM ARCHITECTURE

The greenhouse monitoring system integrates the RF technology and GSM technology and applies the RF technology to the design of wireless monitoring nodes and sink nodes. Through initializing the RF module PTR4000 and matching address, the data collected by monitoring nodes is delivered to the sink nodes which deal with the received data. The processed data is uploaded to the specified server by the remote communication terminal (GTM900-C) based on GSM network. The data transmission between monitoring nodes decreases the power and increases the speed. Besides each monitoring node and sink node form a local area network and the data is sent to the specified server by a common GSM module, which prevents the uploading of single data, thus greatly reducing system development costs.

The monitoring system is mainly composed of three parts: wireless monitoring nodes, sink nodes, and remote communications terminal based on GSM network. The system architecture is shown in Fig. 1.

Monitoring nodes are used to collect parameters of greenhouse environment such as temperature, humidity and so on. Sink node is monitoring data collector and sorter, which is

responsible for monitoring communications between the region and the server. Sink node receives the data sent by motoring nodes, analyzes it to make a decision, and then remotely delivers the processed data through GSM module. Each motoring node is equipped with wireless communication RF module so that the parameters of greenhouse environment are transmitted. Sink node is equipped with not only wireless communication RF module but also GSM communication module which is used to achieve communication between sink node and remote sever.

Figure 1. The system architecture.

between channels is less than 200 s. The hardware CRC error detection is built in the chip so that error rate can be reduced without increasing the difficulty of programming. The chip supports multi-point communication with efficient GMSK modulation and the maximum transfer rate is up to 1Mbit/s. The module address can be set by software so that the data can be output only if the address of the local machine is received. The data collecting module is mainly responsible for collecting parameters of greenhouse environment and we can configure a variety of temperature and humidity sensors required by monitoring greenhouse environment according to the requirements. (Attention: DS18B20 temperature sensor is deployed in the test.) In terms of microprocessor, I select the low-power CMOS microcontroller ATmega16A based on enhanced AVR RISC architecture issued by ATMEL, which is used to control the data collecting module and the RF module. As to power module, solar cells are selected as the power system as in [9]. The entire solar cell system is composed of solar panels, solar charge controller and battery constituting. As the power consumption of monitoring nodes is low, the power system can ensure the normal operation of the monitoring network.

B. The Hardware Design of Sink Nodes

Sink node uses ATmega16A as MCU, utilizes PTR4000 as the RF module and selects GTM900-C as the GSM module. Through controlling the RF module and the GSM module, MCU uploads the data information to the specialized severs. Firstly, sink node sends instructions. Then, corresponding monitoring nodes receive instructions and transmit the data collected by sensors to the sink node through PTR4000. And then the RF module PTR4000 in the sink node receives the data and sends the data processed by MCU to the GSM module GTM900. Finally, the GTM900 uploads the data information to the pre-set server by using AT commands.

Fig. 3 shows the entire hardware system including the power module, the microprocessor module, the RF module, the keyboard and the GSM remote communication module.

III. THE HARDWARE DESIGN

A.

The Hardware Design of Monitoring Nodes

Monitoring nodes use ATmega16A as MCU, and utilize PTR4000 as the RF module. MCU initializes PTR4000 to select the working way of monitoring nodes and match communication address. After monitoring nodes receive the instructions sent by sink node, MCU sends the data collected by sensors to specified sink node through PTR4000.

As shown in Fig. 2, the whole hardware system involves power module, microprocessor module, RF module and data acquisition modules.

Keyboard moduleThe microprocessor module

GSM module

Figure 2. The monitoring node hardware circuits diagram.

In the design, the high-speed and low-power data

transmission module PTR4000 based on one-chip wireless transceiver chip nRF2401A which is issued by Nordic is selected as wireless communication RF module. Ref. [7-8] presented the chip’s characteristics. It is of low power and its operating voltage is 1.9V~3.6V. A 2.4GHz antenna is built in the chip and it takes global open 2.4GHz band, which establishes 128 channels (each channel bandwidth is 1MHz) between 2400MHz and 2527MHz and the switching time

Figure 3. The sink node hardware circuits diagram.

In the design, the microcontroller ATmega16A is selected as the microprocessor to control the RF module and the GSM module instantly and figure out the gathered parameters of greenhouse environment. And PTR4000 is used as the wireless communication RF module to receive the data

information delivered by respective monitoring nodes. I choose the GTM900-C produced by HuaWei as the GSM remote communication module to upload the processed data to the specialized sever. As described by [10], the GTM900-C wireless module is a two-band GSM / GPRS wireless module which supports standard AT commands and enhances AT commands and provides plenty of short messages, voice and data services and other functions. It is an ideal solution for a variety of applications such as high-speed data transmission. In terms of the power module, solar cells are selected as the power system as in [9].

IV. THE DESIGN OF COMMUNICATION PROTOCOL A. The design of PTR4000 communication protocol

When using PTR4000 for wireless data communication, we do not need Manchester coding and are easy to program and apply. As long as we follow the configuration instructions (seeing Table I), what we need to do is just to write the hardware address of the nodes and sink nodes, data length and the rest of the configuration word to the status word. In this system, the sink code address is 0x3a3b3c3d3e and the monitoring node addresses are 0x1a1b1c1d1e, 0x2a2b2c2d2e. Both nodes and sink node are 16 parity bits. The parity bit is enabled, single, burst mode, 1Mb/s, crystal frequency 16MHZ, operating frequency 2400MHZ and the lowest bit 0 is emission (it can be temporarily configured when needing to receive data temporarily).

TABLE I.

PTR4000 CONFIGURATION KEYWORD LIST

functions, is the ideal solution for various applications such as high-speed data transfer.

GTM900-C integrates TCP/IP protocol and uses the expansion of the internal the AT command. According to the manual of the GTM900-C wireless module AT commands, users need only send the compiled AT command to the wireless module GTM900-C through the MCU and a serial port, then it can be realized on the initialization and data sending. Its main steps are as follows:

Command "AT" / / test GTM900-C is ready; Return OK;

Command "AT + CMGF = 1" / / set to send data in the form of text; Return OK;

Command "AT + CMGS = '11 phone number' / / connect to the server, set the server number; Return ">";

Type the contents and sent them by the means of “Ctrl+Z"; Return OK;

V. THE SOFTWARE DESIGN

A. The software design of monitoring node

The key of the design of Monitoring nodes of process is communication of microcontroller and PTR4000 module. Its workflow chart is shown in Fig. 4.

When Monitoring node is electrified, sensor and RF module PTR4000 will initialize, and then PTR4000 to enter configuration mode. We based on PTR4000 to write configuration, so that it is in receiving mode. Until PTR4000 receives the sink node command, the monitoring node will start to work. After the completion of the acquisition data, RF module PTR4000 enters delivery mode. Collected data will be sent to the sink node. After sending, RF module PTR4000 will be into receiving mode and wait for the arrival of the next location 119:112 8 DATA2_W The length of the data channel

2

1

23:18 6 ADDR_W The bits of the address check digit

13 1 RFDR_SB Communication Rate(1Mbps or

250Kbps)

Power

7:1 7 RF_CH# The setting of the frequency

point

Basic Configuration Functional configuration

B. The design of GTM900 communication protocol

HUAWEI GTM900-C wireless module is a two band GSM/GPRS wireless module, it supports standard AT commands, and enhances the AT command, and provides a rich text messages, voice and data services, and other

Figure 4. The workflow chart of monitoring nodes.

B. The software design of sink node

It’s the key to SCM, GTM900 module and PTR4000 module communication. Its workflow chart is shown in Fig. 5.

data; The indoor test was selected in YiFu building study room. In an interval of a wall between, through comparing the sending data with receiving data, we found that the error-free data transmission distance reached 13 meters. More than the distance, we also didn’t receive any data.

In the process of the experiment, we found that the received data is either right or we didn’t receive any data; there is no error rate of the problem.

VII. CONCLUSIONS

According to the characteristics of the greenhouse environmental monitoring, the article puts forward a kind of design scheme of greenhouse environmental information remote monitoring system based on RF technology and GSM communication technology. And it introduces the overall structure of the system and the software and hardware design method of each part in detail. It provides a cost-effective solution for the small and medium-sized greenhouse monitoring.

REFERENCES

Figure 5. The workflow chart of sink node.

After powered on, the sink node device initializes and sets the server address (i.e., input 11 phone number). Then, RF module PTR4000 is into sleeping mode and Microcontroller start timer. After the prescribed time, we make PTR4000 at the sending mode via writing configuration word to RF module. At this time, sink node sends commands to the monitoring node. The monitoring node starts to collect relevant data and information in greenhouse, and sends the collected data to the sink node. Sink node receives the data and processes it. Under the control of the microprocessor, the result is sent to the server through the GSM module (GTM900-C). At the moment we realize the function of timing acquisition. After interrupt returning, the system will return to standby mode again and wait for the arrival of the next sampling period.

VI. THE EXPERIMENTAL RESULTS

After establishing the greenhouse environment monitoring system, test experiment was carried out in the open area and indoor to test the transmission distance and the BER of the system. The open experiment was selected on the school track and field. Through comparing the sending data with receiving data, We found that the error-free data transmission distance was up to 50 m, more than the distance we didn’t receive any

[1] Yang Wei, Li Min-zan, and Wang Xiu, “Status Quo and Progress of

Data Transmission and Communication Technology in Field Information Acquisition,” Transactions of the CSAE, 2008, vol. 24, pp. 297-301.

[2] Yang Jing, Bai Bao-liang and Li Han-dong, “Design of Greenhouse

Environment Monitoring System Based on GSM and WSN,” Journal of Anhui Agricultural Sciences, 2012, vol. 40, pp. 2497-2498, 2556.

[3] Gao Feng, Yu Li, Zhang Wen-an, Xu Qing-xiang and Yu Li-jie,

“Research and Design of Crop Water Status Monitoring System Based on Wireless Sensor Networks,” Transactions of the CSAE, 2009, vol. 25, pp. 107-112.

[4] Tang Yi-feng, Chen Xin-hua, Feng Hui and Luo Bin, “Design of

Wireless Sensor Network Node for Environmental Monitoring in Greenhouse,” Journal of Hunan Agricultural Sciences, 2010, pp. 146-148, 151.

[5] Wang Dong, “Research and Realization Control System of Greenhouse

Environmental Based on Muti-Sensor Fusion,” Thesis for Master Degree, Northwest A&F University, 2012.

[6] Wang Yi and Zhou Jie, “Design and Realization of Remote Monitoring

System of Greenhouse Environment by Using GSM,” Modern Electronics Technique, 2008, vol. 31, pp. 151-154.

[7] Liao Ping and Qiao Gang, “Short Range Wireless Communication

System from One to Many Based on NRF2401,” Modern Electronics Technique, 2006, vol. 29, pp. 18-20.

[8] Zhang Chong, Lin Xiao and Liu Ping-jian, “Design for Remote and

High Speed Wireless Communication Based on NRF2401,” International Electronic Elements, 2007, vol. 14, pp. 84-86.

[9] Zhu Ying-li, Song Jing-jiang and Dong Fu-zhou, “Applications of

Wireless Sensor Network in the Agriculture Environment Monitoring,” Procedia Engineering, 2011, vol. 16, pp. 608-614[Elsevier Ltd. Selection, in the press, 2010].

[10] Xian Jin-long and Yang Yang, “Study and Implication of Remote Grain

Situation Measurement and Control Based on GTM900,” Journal of Henan University of Technology ( Natural Science Edition), 2011, vol. 32, pp. 79-82.