The Research On The Reader Modeling And Signal Test Of UHF RFID System

Radio Frequency Identification (RFID) technology is a non-contact automatic identification technology. With the development of it, there are more and more applications of it in all spheres of society, which has brought huge economic benefits for society. At the same time, it faces with various difficulties and challenges, such as the disunity of the standard, the differences of the uses of the frequencies of Global Ultra-high Frequency (UHF) and so on. In China, the correlated formal standard even has not been work out, UHF-band spectrum allocation scheme has not yet formally announced, only the related testing is positively conducting; in addition to that, China's RFID products have not been officially set up third-party testing organizations so as to test the products. In order to facilitate the early introduction of China's standards and early publication of the frequency distribution, we have a need for radio frequency identification products and reasonable scientific test and measurement, in order to urge the faster and better development of Radio frequency identification technology.Based on the above circumstances, this thesis studies the readers for ultra-high frequency radio frequency identification system. First of all, the Modeling and Simulation for reader to 915MHz. There are two types for reader to 915MHz: TYPE A and TYPE B. In this thesis, two types of reader to 915MHz were carried out both in time-domain and frequency domain Simulation. Time-domain Simulation has drawn the data streams of the reader which is accorded with the theoretical design and can meet the requirements of the agreement; frequency domain Simulation can elicit the output power, modulation efficiency and reader output signal spectrum, and later conduct the modeling and simulation for the frequency hopping system.Secondly, the thesis does some analysis for the existence of time-varing signal of the reader, in which the frequency hopping signal has been selected to be measured and simwed. First, the writer of the thesis analyzes the characteristics of the time-varing signal, and the characteristics and working principle of the frequency hopping signal, so the writer has set up a mathematical model for the Frequency-hopping communication system. Withall, in view of this time-varing signal, time-frequency joint analysis has been put forward, and a function of time-frequency joint analysis has been established, in addition, three common methodologies of time-frequency joint analysis have been introduced, what are: time-frequency joint analysis, Wavelet transform and Wigner-Ville transform, the writer also provides some comparative explanation about their respective advantages and disadvantages of the above three. Lastly, an S-transform of the frequency-hopping signal simulation and parameter estimation analysis methods has been put forward, which can identify the frequency-hopping signal very well and provide a very good condition to extract the parameters of frequency hopping signals.