Design And Research Of Water Depth Measurement System For Permeable Ice Layer

Polar ice layer is a natural defence for water.Measuring water depth through ice layer has a strong practical significance for science examination or hydrological survey.Based on this problem,this paper proposes a technology and designs a set of equipment for measuring water depth through ice layer,which aims to provide theoretical basis for the study of water depth measurement through ice in polar regions and provide the necessary technical support for the location of the polar science examination station,polar transportation,hydrological survey and so on.The system of measuring water depth through ice layer designed and realized in this paper is a water depth information measuring system with relatively complete function and low-power consumption.It mainly includes the collection of tapping signals and underwater echoes,the reception of GPS information,the processing of underwater echo signals and a programming software which can communicate with the computer designed by Qt.The main works of this paper are as follows: Firstly,the feasibility of measuring water depth through ice layer is verified.In theory,the sound source level of tapping source is measured by experiment.The model of sound wave propagating in water is established by spherical wave theory.When sound wave enters ice layer from water,the sound wave can be regarded as an excitation signal and the process of the signal through subglacial surface to ice surface can be deducted by standing wave theory,then the function of acceleration g on the upper and lower surface of ice is obtained.The theoretical model of the process from the generation of knock signal to the pick-up of equipment is established.Secondly,the system scheme design of this equipment based on technical index is completed by analyzing the requirements of equipment designation.The design uses a modular design concept to realize the design philosophy of miniaturization and low-power consumption: the central control unit uses the low-power STM32F407.The signal passes through the conditioning circuit,and the MCU collects the signal and GPS data,finally the data is stored in the SD card.The acquisition board communicates with the PC through the serial port.The system uses a 5V power to supply,and adopts the SW mode for debugging to realize its miniaturization idea.The system can select the acquisition mode and storage mode by pressing the button.In the acquisition mode,it will continually collect signals when a tapping signal appears it starts automatically counting.When the echo signal arrives,the equipment stops collecting,filters and the collected signal,does the processing of cross-correlation on it and takes its envelope.Time information is obtained by using a method of peak detection,and water depth information is calculated.The storage mode is behind of the acquisition mode;the data will be collected and stored in the SD card by pressing the key.Finally,the design and implementation of the system unit was complicated,for example,the component selection,circuit design and debugging work were completed,which realizes the system hardware.Through the Songhua River experiment in winter,the feasibility and effectiveness of the system is verified.