Fresh Water Real-Time Monitoring System Based on ... - IEEE Xplore

2011 IEEE Conference on Open Systems (ICOS2011), September 25 - 28, 2011, Langkawi, Malaysia

Fresh Water Real-Time Monitoring System Based on Wireless Sensor Network and GSM Ummi Nurulhaiza Za’bah & O.Sidek CEDEC(Collaborative μElectronic Design Excellent Center), Universiti Sains Malaysia, Engineering Campus, 14300 Nibong Tebal, Seberang Perai Selatan, Pulau Pinang, Malaysia [email protected] [email protected]

Muhammad Azwan Nasirudin CEDEC(Collaborative μElectronic Design Excellent Center), Universiti Sains Malaysia, Engineering Campus, 14300 Nibong Tebal, Seberang Perai Selatan, Pulau Pinang, Malaysia [email protected]

issues that need an effective solution to face the threats as well as it will not affected to our everyday life and also to ensure the sustainability of the ecological system. In some places such as in [10] describes that the pollutant effluent derived by mining sites has affected the underground water source such as wells, one of the important water source for a poor peoples. Recently, wireless radio frequency technology has been widely used the solution in various cross boundary application either to provide wireless data transportation infrastructure or remote controlling system. Hence, the Wireless Sensor Network (WSN) has took place to be an ideal technology platform for environmental remote monitoring infrastructure by looking at the benefits of its low power consumption and cost, smaller scale of size, networking, sensing flexibility, and also mobility of nodes. A less expensive system to monitor both underground and surface water is deployed using WSN technology, which claims as an ideal approach in Zambia [10]. The water quality management system using Wireless Sensor Network (WSN) is a kind of an autonomous solution to enhance the environmental observation technology. As everybody knows that water is the basic element for living, the most important source for everything in the ecosystem and without it no life would present on the earth. Precision and automated environmental monitoring system becomes an essential in order to ensure safe ambient for creatures and human life and it would not disrupted especially at fresh water sources. A WSN is an ad-hoc network system composed of a great number of tiny low cost and low power consumption sensing nodes which are capable of sensing, calculating and communicating data [3].Therefore, this project has intended to deploy the WSN system to gain real-time water quality parameters such as water temperature range from 0-100°C, water 0-14 pH scale, turbidity 0-1000 NTU and dissolved Oxygen 0-8ppm.

Abstract—The rapid development nowadays contributes to unbalance of natural ecological system which leads to changes of earth climates and natural resources such as fresh water quality. Limitation of human resource to do real-time monitoring and data collection regarding this environmental issue will lead a major problem to fresh water supplies at coming decades. This paper describes an approach of Wireless Sensor Network (WSN) application to do real-time data collection at the fresh water resources such as rivers, lakes or wetlands areas to obtain proper water quality parameters measuring. The WSN system is used as a platform to monitor the fresh water quality readings, deployed at distributed location which each nodes will able to interface with various water quality sensors. The system will use a green power source via harvesting the solar day light with optimized power management to enhance the long life operation at remote rural areas. Then, the collected data from each node will go to sub-base station as the device network coordinator and to the monitoring station server via GSM network. This system powered by PIC16F886 nano-watt MCU, with RF XBEE 802.15.4, ISM 2.4 Ghz module for each node while the Coordinator device integrated with GSM/GPRS modem and monitoring LCD. Keywords-Wireless Sensor Network, Water Quality Monitoring, GSM, ZigBee Protocol, Sensor Node, Environmental Monitoring, Fresh Water

I.

INTRODUCTION

Fresh water is the symbol of living creatures on the earth, defined as water that contain less than 500 parts per million of salt that dissolved in it. The natural resources of fresh water can be found at rivers, streams, lakes, ponds, groundwater, cave water, springs, floodplains, and wetlands [1,6]. In Malaysia, the rivers system, groundwater, lakes and wetlands are the main fresh water sources that give us water supply for drinking, agricultural and other essential usage. By the latest observation, water resources have become reduced and also large amount of it have been polluted. Water pollution can be caused by several factors such as domestic sewage and animal wastes, indiscriminate use of pesticides, rapid industrial development and urbanization have given rise to the increased quantity and diversity of toxic and hazardous wastes [2]. The observation and management of fresh water become crucial

II.

A. WSN and GSM Networks This architecture is then implemented in the sensor nodes that would construct a wireless networking data collection at

This research is supported by USM Short Term Grant 304-PCEDEC60310032

978-1-61284-931-7/11/$26.00 ©2011 IEEE

SYSTEM OVERVIEW

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network. The further description on ZigBee then is to define the protocol created by Zigbee Alliance which are featured as:

the target fresh water source areas, for example, lake and river that are likely to replace the conventional manual data collection system. Figure 1 shows the overview of the proposed system consisting of sensor nodes that installed randomly with water Temperature, pH, Turbidity and Dissolved Oxygen sensors that will set as End Device in the network. Then, these devices will be connected through Coordinator Device that according to unique PAN (personal area network). This network topology supported by multi-hops data transfer until reach to destination address at Coordinator Device. A same color node means they are in the same PAN but with different node IDs. These nodes will carry out routing path to their neighborhood node(s) until the beacon reaches the base station (Coordinator Device). At the Coordinator Device, the collected data will reach the remote data base server at CEDEC, USM through GSM 900Mhz commercial service provider networks, by Short Massages Service (SMS) format. The nodes in the target area will send data simultaneously to the destination within the programmable interval time. This will allow real-time data collection delivered to the monitoring station.

• • • • • • •

Low Duty Cycle- to enhance long battery life Support for multiple network topologies such as point-to-point, point-to-multipoint and mesh networks Low latency-suitable for real-time observation Direct Sequence Spread Spectrum (DSSS) Up to 65,000 nodes per network 128-bit AES encryption for secure data connections Collision avoidance, retries and acknowledgements

The core ZigBee specification defines ZigBee's smart, costeffective and energy-efficient mesh network. It's an innovative, self-configuring, self-healing system of redundant, low-cost, very low-power nodes that enable ZigBee's unique flexibility, mobility and ease of use [4]. An energy saving coverage will also conclude in WSN futures as it is has a small size and battery life dependence which limited to get powered [12][13]. Hence, the ‘active’ and ‘hibernation’ nodes will help to conserve the power source [13]. III.

PLATFORM DEVELOPMENT

The proposed system is the first model platform built for this project that can perform a multi-sensor interface with 8 or 10 Bits ADC resolution at 8 channels and I2C digital sensor interface such as SHT-75. The PIC16F886 is the main MCU for this board version that drives the logical task such as the EUSART serial data, Analog-to-Digital (ADC) conversion and logical processing. The Microchip PIC16F866 offers best in class with its nanoWatt™ technology, wide range of input voltage 2V-5.5V, 20nA standby current packaged with 28-pin CMOS 8-bits which can reduce the power consumption significantly compared to previous PIC16F87XA series [5]. The input power to this circuit system regulates at 3.3V by LM-1117 LDO voltage regulator. The proposed board also has a built-in V/I conditioning circuit for multipurpose 4-20mA industrial type sensor signal input. The voltage reference is also can be adjusted by trimming preset resistor for ADC’s v+ reference set point and offset adjustment. Figure 2 has to show the block diagram for the sensor node circuit.

This proposed system architecture will also allow a watchdog alarm operation, which is the system will discard the interval time programmed and automatically activated sensor(s) to send alarm data if there is the water reading reach the threshold limits. For example, the lake pH reading reaches to abnormal acidic value. Additional sensor for air quality reference also could be added by drop-in network topology system. B. ZigBee IEEE 802.15.4 By referring to Figure 1, a previous networking used in this project model is the Point-to-Point and Point-to-Multi Point network setup that commonly used in simple sensor networks. However the recent stage of this project going to utilize full function of ZigBee application standard to obtain more robust network configuration. ZigBee keyword is a kind of standard protocol that combines the physical Radio Frequency (RF) layer complies with IEEE 802.15.4 physical radio specification and operates in unlicensed bands commonly are 2.4 GHz, 900 MHz and 868 MHz spectrum [4,8]. This project used the 2.4 Ghz ISM spectrum band for all nodes except the GSM modem

This platform initially used with XBEE 802.15.4 RF module for data transportation and it is interchangeable with XBEE Pro or XBEE PRO Series 2 ZNet 2.5(mesh network).

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A trial experiment carried out for this project using the WQ101-water temperature (as node #1) and WL 400-water level (as node #2) to test the ADC computation until the data sent to the base station (Coordinator) and linked to GSM network (text SMS). The ADC computation in PIC16F886 was program at AN0 input of PORTA with 10-bits, equals to 1025 resolution. The lower limit for ADC conversion started at

It’s operates by 2.8-3.4V voltage supply and gives 3.3v TTL serial output (DIN, DOUT pins) for data and programming terminals. The current XBEE module used for this platform has a maximum range up to 30 meter distance line of sight (1mWatt, 0dBm) and only support point-to-point and point-tomulti-point networks topology [7]. User need to setup the device to become Coordinator or as the End Device using AT commands set (via WINDOWS HyperTerminal) or X-CTU software provided by Digi. A Coordinator has to organize and establish End Device(s) in a PAN network can route data transportation to/from other nodes and could be the destination/ source of data packet. On the platform board, XBEE module communicates with MCU by serial UART at 9600 baud, 8 bits data with no parity. At a Coordinator device board, it also can be connected by an optional 4x20 Alpha Numeric LCD for direct real-time data readings or directly connected to PC via RS232 COM Port for saving data in system database. That setup is applicable if the database server PC locally networked within the XBEE RF coverage. Otherwise, an alternative way to extend the network is via Global System for Mobile (GSM), a payable mobile phone networks using GSM 900Mhz modem. The communication between MCU and GSM 900/1800Mhz (Wavecom Fastrack M2406B) device is done through Serial RS232 level by AT commands at 9600 baud, 8 bits data and no parity.

0.66V until clipped at 3.3V for maximum conversion point. An output signal from the sensor is giving the current (Isensor) reference with linear proportion to measurement input. For further steps, an electrical circuit element is applied to model the relation of resistance and current correlation. Hence, to simplify it, the algebraic relationship between resistance and current is denoting by Ohm’s Law [14]. Equation (1) is to shows how we convert to linear voltage drop by manipulates it into (2): Vout = I sensor x Rload

(1)

For the logic 3.3V voltage level, the Rload is fixed at : Rload = Vout / I sensor

(2)

Rload = (3.3)/(0.02) Fixed resistor for Rload is 165. Voltage Resolution = 1 Least Significant bit (LSB) value

Figure 3 shows a Coordinator circuit block diagram with two optional base station systems; one with the dash box configures direct communication of XBEE module to Server PC if a server located locally in WSN network coverage. Secondly, an extension method to carry data for a long distance remote server is by utilizing the GSM network provider via GSM modem as shown above. The receiving server terminal has to connect with another set of GSM modem to retrieve the sent data. IV.

=

(3)

Where N is the number of bits or the word length.

Voltage resolution of an ADC is defined as the ratio of full scale voltage range to the number of digital levels that are accepting in that range. It is a measure of the accuracy of the ADC. Equation (3) showing the higher the resolution, the higher the number of levels accommodated in the voltage range and, consequently, the lower the quantization noise [15]. As the water quality sensor produce a linear output signal, this conversion will correlate with the raw (I sensor) as shown in Figure 5, as the experimental result. Therefore, the system is proven, to shows a linear voltage level data were captured via PC RS-232 terminal that was connected to Coordinator node (after MCU and nodes). The GSM modem option is used either

EXPERIMENTAL AND FUTURE WORK

Since this project is still at preliminary stage, a complete water quality data experiments are not carried out yet. Recently, an initial experiment to test the system functionality was successfully done and few prototypes boards were produced to verify the concept (Figure 4). The experiment was done using a 12VDC power supply and 12V 1000mAh battery to test the wireless networks both for WSN and GSM system.

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to send water quality data from a rural place or for emergency alarm (supervisory) purposes. The improvement is undergoing to enhance the robustness of networks by integrating the on board DC-DC boost converter circuit and solar energy powered system [9].

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CONCLUSION [12]

As the sensor nodes are using batteries [10][11][9], a smart power system and networking activities are mostly take into consideration for WSN platform design to solve this critical issue. The alternative source such as Ni-MH, Li-ion or Li-Po battery would become a better choice comparing to conventional lead-acid or Ni-Cad in terms of current-hour sinks capacities and charging/life cycles. The multiple of solar panels, battery packs and intelligent power processor board would be a better option to enhance the nodes life [10], but at some application it needs to consider the size of a node. A solar-battery charger system is also need to be carefully design to meet the environment surroundings (limitation of lights) which able to support the day-night time operation. A microwatt MCU is the best choice to be a nodes controller, and also the selection of network topology will optimize the nodes life.

[13]

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