Circuit Design Of FPGA-Based Short Baseline Positioning System

Along with the rapid development of science and technology, acoustic technology hasalso achieved rapid development, especially in recent years, the exploitation of underwaterresources has increased, the request level of underwater acoustic technology has improved,and all that have promoted the development of underwater acoustic technology. The ocean isrich in resources, the exploitation and utilization of the ocean has great value for thedevelopment of the country, not only in economy, but also in military. With the constantlydevelopment of marine resources and the needs of military development, the requirement ofthe underwater carrier positioning technology has become stricter, and every country haspaid more attention to the development of acoustic positioning technology. Acousticpositioning system refers to the accurate positioning system of target, and it is mainlydivided into ultra-short baseline system, short baseline system and long baseline system.This paper recommends using short baseline positioning technology to develope a setof positioning system, which detects the reliability of the system with the positioning ofmodel aircraft in water. This system mainly consists of two parts: the first part is the beacontransmitter, installed in the model aircraft, and it is used to receive closed data from modelaircraft, translate the data into time delay coding, control the time delay between pulsesaccording to time delay coding when send a signal, and also realize the clock function; thesecond part is the receiver, installed on land, it is used to receive positioning and closedsignals from model aircraft, and run the inspection. The receiver consists of two circuitboards, an analog board and a digital board. The analog board receives the signal fromhydrophone, using four ways of analog receiving circuit, and amplifies and filters the signal.Digital board makes digital process of the signal, then detects the arriving time of the signal,and sends the data to PC software. The key of this paper is the accurate detection of signalarrival time, and the position and closed information of the model aircraft can be calculatedonce geting the signal arrival time of each channel. In this paper, the main work of softwarepart can be divided in two parts: one is to realize logic control functions, and control thebottom parameters of circuit board; the other is to realize the quadrature receivingtechnology, and set the threshold of the signal according to the energy of the signal after itsarrival.This paper introduces the implementation principles and methods of this positioningsystem in detail, and simulates the algorithm used above. At last, this paper particularly analyses several factors of leading errors in the system, and puts forward the correspondingsolutions and measures.