The Design Of Underwater Monitor System For Small Water Aera

With the growing importance of the water environment, as well as water scarcity, water pollution and other effects of human movements, establishing water environment adequate supervision has become China and the world government’s urgent task. For small waters (rivers and lakes), we need the sensor nodes to monitor their temperature, chemical composition, pH value and so on various parameters. These nodes are generally required to be installed in the water with long-term monitoring. Thus, the development of a low-cost, efficient and low-power underwater monitoring platform suitable for such small waters is of great practical significance.This thesis has developed a platform of underwater monitoring function by monitoring nodes placed in water. The design process include communications hardware circuit design, selection and procedures written for communication modem mode, communication protocols written and laboratory environments so long with open water in the experimental test.In the summary of a variety of communication methods, the paper chooses the underwater acoustic communication as a carrier communication. Because of the characteristics of underwater acoustic multipath channel itself, the Doppler effect and the space-time distortion, the traditional communication coding often require high performance and high frequency master chip. This paper introduced an innovative linear modulation and coding (Chirp FSK) method and programming it to a low-power MCU chip to ensure accuracy, speed of communication and the realization of a low-power node operation.To ensure the reliability of communication, the paper individually designed circuit for excitation and receiving acoustic signals. We using a RFID-style wake-up mode to achieve ultra-low power operation of the system. For Transmitting circuit, the paper compares the various power amplifier circuit design and chooses the most effective energy-saving amplifier circuit. For receiver circuit, this paper combines the weak bioelectric signal amplification circuit design methods and radio frequency circuits Wilkinson power splitter circuit principle. We design a highly reliable filter amplifier circuit to ensure the accuracy of communication. And extensively tested in a lab environment communication prototype with its error rate will be controlled within 0.06%.In terms of system implementation, we design the master-slave communication node through a combination of information between the mobile nodes and fixed nodes. In the use of-the sensor networking we establish a monitoring network in the water. A 50-100 meters radius open lake were tested for the realization of the water environment monitoring parameters.