Design Of Underwater Life Detection System Based On FPGA

In recent years, shipwreck has occurred frequently. To improve the efficiency of disaster relief has become an important issue of underwater life rescue. At present, with the rapid development of communication technology and embedded technology, the underwater detection technology has made some achievements such as roaming, robotic fish, fluorescence tadpoles and other water dropping tools. They played an important role in the field of military, commercial and rescue. Underwater life detection technique was the focus of research over the salvage, and it was of great significance to recover the loss of life and property, and also played a positive role in promoting the development and utilization of underwater biological resources and the energy of the ocean. Based on the comparison at home and abroad on life detection technology, I designed an ultrasonic underwater life detection system with FPGA hardware platform.The emphasis of this article was on the analysis of the life characteristic signal, extracting useful information accurately from the life signal features, and then acquired the characteristics of the object using relevant algorithms. This design used ultrasonic waves to transmit signals and used FPGA hardware platform as control center. This design used VHDL language for software program and used ModelSim to simulate. I did a lot of underwater life detection experiment for practice. In accordance with the expected results, the function of judging the material characteristics of the underwater target and measuring the distance of the object has been realized. The ultrasonic underwater life detection system was mainly composed of an ultrasonic emission circuit, an ultrasonic receiving circuit, a signal processing circuit, a control circuit, a temperature compensation circuit and an audio output circuit. The following was the workflow of the system. Ultrasonic transmitter signal circuit emitted a powerful ultrasonic signal, the ultrasonic signal was reflected after encountering obstacles then the reflected signal was received by ultrasonic receiver while the received signal was very weak and contained background clutter signals. After the signal was processed through the filter circuit and AD converter the signal was sent to the control circuit. By analyzing echo signal the control circuit extracted vital signs signal to analyze and operate. The result was exported with PWM signal to make the audio circuit make noise. With that, underwater rescue workers could determine the distance from the target object based on the size of the sound signal sent from the device.The design used high-speed signal acquisition circuit to collect the life characteristic information of the echo signal. Then the control center processed life characteristic information Based on the background of ultrasonic wave theory, the method was used to calculate the reflection coefficient of the interface, so as to judge the characteristics of the target object. The transmitting circuit used second-order active filter circuit for processing the received echo signals and acquired the higher signal-noise-ratio. By using HC-SR04 to measure the distance of the target object, the accuracy was high. The temperature compensation circuit could accurately collect the environmental temperature and correct the distance value. After debugging each module they could work correctly, the whole could accurately determine the target object material characteristics and the distance of the target object. This design had many advantages liked low cost, low power consumption, simple hardware structure, convenient portability, simple operation and so on. The system had a certain reference value for the design of underwater life rescue system.