The Communication System Of The Car To Grab A Collection Of Technical Research And Realization

The high-speed magnetic levitation (maglev) train transmits the measuring and controlling information by Train-ground communication system as well as the base controlling center. An efficient and reliable train-ground communication system is the key to insure the safety of the train and the smooth transmission of commands and attempts. However, this transmission could be affected seriously because of multi-path environment and high-speed movements. This communication system works at the high-speed and in bad electromagnetic condition; the equipments in the system is in a large quantity and a far-raging distribution; the data throughput of the communication system is great and the time requirements is critical. The 38GHZ train-ground communication system ensures and improves the performance of wireless communication system by use of millimeter wave (38GHz), signal diversity, Forward Error Correction, CPFSK modeling method and so on. These works ensures the safety and trustiness of train.It is based on the communication environment on maglev train in this paper. Meanwhile, the topic in this paper comes from the National"863"plan about communication system for maglev train, the task is to realize the diversity-combining function in communication system. Based on the theory and structure of train-ground communication system, The diversity-combining system as well as its essential technology: the signal-noise-ratio (SNR) estimation for train-ground communication is discussed in this paper. The work was carried out from the following aspect through the aspect of simulation, SNR estimation and the development of diversity combining system:1. First of all, the overview of maglev communication and application of diversity-combining function in wireless communication as well as the train-ground wireless communication system, the multi-path environment and the anti multi-path technology were introduced. Then based on these theories, the diversity combining, equalization and SNR estimation technology is also introduced. These are the base of the researching and development of the following parts. 2. Four SNR estimators were introduced totally. Two are based on AWGN environment and the others are based on multi-path environment. At the same time, performances of the algorithms especially the first 2 algorithms are analyzed. Under the condition of multi-path environment the performance of the estimators has been improved successfully through the equalizer technology.3. For the actual condition of diversity combining system of vehicle-ground system, to solve the question of how to obtain the quality of the baseband signal, a new SNR estimator based on correlation detection has been presented. Furthermore, Its validity and feasibility has been proved by the simulation as well as practical use in the real system4. The FPGA-based diversity and combing is developed based on these theories and simulation results. Meanwhile, as for the requirement and property of vehicle-ground communication, the new SNR estimator has also been introduced in these systems. Moreover, the validity and stability has been proven by debugging and practical application of this system.