According to the WHO by 2025 half of the world's population will be living in water-stressed areas. To provide healthier water in the future an IoT Smart Water system has to be built.
To collect the various water parameters (pH, Temperature, Turbidity, etc) from different locations a mesh of sensor nodes needs to be deployed in major waterway areas. My proposal is to create sensor nodes that will collect real-time data and send it to a server through a gateway. There will be several nodes, deployed in different locations under one gateway. The nodes will contain various sensors (pH, Temperature, Turbidity), signal conditioning unit, Microcontroller, Battery, Solar Panel, Power management unit, LoRa module, high gain antenna. The nodes will be independent of power source, energy efficient and self-power generatable, able to provide long-range connectivity and waterproof.
[ DESIGN ]
Every sensor node will be allocated a unique id which will be used to identify them while receiving the data. After installing, the node location should be updated. As the nodes will be fixed at their location so there will be no need for GPS devices. DS18B20 waterproof temperature sensor, Analog pH electrode, GE Turbidity sensor will be used in the nodes. The sensor measurements will be processed through a signal conditioning unit and then fed into the microcontroller. I will be using AVR microcontroller. For Low Power and Long Range communication, LoRa modulation will be used, which use ISM band (i,e industrial, scientific and medical radio bands) for communication. By using an 18-20 dB antenna, 2-3 km range can be easily achievable. The measurements will be sent to the Gateway by an interval of 20 minutes as the water parameter does not change rapidly. For powering system, a 2S 2000 mAh Li-ion battery(7.4 V) will be used. The battery will be charged by the Solar Power system (consisting of Solar panel, MPPT charge controller) during day time. By this method, the system will run forever with its self-power generation capabilities. For better efficiency, the system will go to deep sleep mode (consume power in microwatt range) for 20 minutes duration.
A gateway consisting Raspberry Pi and LoRa Gateway with high power receiver have to be installed within 2-3 Km radius from the sensor nodes with a height of 15-20 meter for better communication and less data loss. Multiple sensor nodes of multiple locations will be connected to one Gateway. The date from the sensor node will be encrypted and the same will be decrypted by the gateway and send it to the server. The data of the nodes will consist Date and Time stamp, Unique node id, Sensor measurements which will be used as a Big data to influence the decision making regarding water pollution.
[ COST ]
The approximate upfront cost of a Sensor Node will be around $55 - $60 and there will be no recurring cost for that. The cost for a Gateway will be around $120 - $150 and there will be a recurring cost for providing power and internet to the gateways. Bulk import and manufacturing can reduce the cost by 30 %.
[ PRODUCTION ]
A waterproof enclosure will be used for producing the sensor nodes. A 4 layer PCB will be designed and all the units like the Power management unit, Signal conditioning unit, Processing unit, LoRa modulation unit will be embedded over there. The sensors will be placed on the bottom which has to be dipped inside the water and Solar panel will be placed on the top. A high gain antenna for communication will be placed on the side of the enclosure. A micro USB port will be there for configuring the system.
The Gateways will be produced using Raspberry Pi and LoRa gateway Hat.
Through the sensor nodes, there will be a huge database created consisting of water quality parameters of different locations at different times. This data will be used to monitor and analyze the waterways better which leads to healthier water solutions.