Design And Implementation Of CSS Wireless Location And Tracking System

With the development of electronic technology, electronic measurement is developingrapidly. And the study of electronic positioning technology has also been gradually extendedfrom the military, aerospace and other fields to commercial production and civilian areas. Thefocus of the research has shifted from the measurement feasibility, measurement accuracy tomeasurement flexibility, economic cost and other aspects. In this paper, the positioningtechnology based on practical applications in daily life is studied.Firstly, this paper analyzes the various positioning system, and contrasts characteristicsof existing products and the performance of its positioning accuracy, positioning range andother aspects, then concludes that the positioning system based on Chirp Spread Spectrumtechnology achieves the requirements of positioning accuracy, production costs, and thedegree of difficulty in daily life.Secondly, with analysis of the principle and the scope of the main measurement methods,we establish the technical solutions: In order to resist the effects of multipath interference andnoise and improve location accuracy, we choose Symmetric Double Sided Two Way Rangingalgorithm as ranging scheme of the system; In terms of positioning algorithm, we choosecommon trilateration, through measuring the distance of the label node between three anchornodes absent from along the same line, and combining with the coordinate information ofthree anchor nodes can obtain the information of the tag; And in order to make more accuratemeasurement results, as this paper uses four anchor nodes for ranging, it will produce fourdistance values. Through a series of simple arithmetic and it is an over-determined equation,to be able to solve a more accurate value, we use a least-squares algorithm for the optimalsolution, in order to obtain a high precision measurement.Moreover, combined the NA5TR1RF chip of Nanotron company of Germany and itsassociated data, the paper self-designed a RF transceiver module based on CSS technology.On the basis of the communications protocol and related software application interface of Nanotron, we do the corresponding application development and achieve the communicationand measurements among them. Then on this base selects the appropriate system parametersthrough several hardware and software debugging and system testing, and we design acomplete and reliable positioning system based on this module.Finally, this paper designs experiment to measure the communication distance, rangingprecision and display of real-time location on computers of the nodes in order to test theperformance of this system. The results show that the positioning system can be a good resultfor location tracking of mobile target, and it achieves the desired design requirements well.