The Method Of Freight Train’s Location Based On Spread Spectrum Communication

With the improvement of railway automation level, while high-speed trains and other passenger train control system become complete, on the other hand, real-time of freight train control is relatively on primary stage; how to improve the real-time degree of freight train control system has been one of the critical problems in the railway operation. Therefore, this article describes the key principles of spread spectrum communication technology and the applicable characteristics by the time difference and the difference of signal strength, Compute Pseudorange. According to the algorithm for processing the pseudorange calculate the estimated value of the position coordinates. Contrast truck actual coordinates of the location, find the error. Finally proposed a method combining spread spectrum and radio communications to calculating the position.Firstly the paper introduce the significance of the location information in the train control system, the current development of location technology at home and abroad. Next, introduce the spread spectrum communication technique, comprising:Shannon, select a spreading code, synchronization and simulation; then describes the radio communications system, including:the way of radio communication system, the multi-user in case of anti-collision algorithm and conducted experiments for a response rate of laboratory equipment used for the estimation of the accuracy of the method was provided. For multiple users’identification problem, proposing CDMA technology to solve the problem. Finally, the establish math model of three location algorithms:model AOA algorithm, TDOA algorithm, RSSI algorithm simulation; According to the simulation results, find that using spread spectrum communication-radio frequency methods to satisfy the requirements of train location.