Design Of EAS System And Study On Anti-interference Detection Techniques Of Electronic Tags

EAS system, also known as Electronic Article Surveillance system, is widely used in various areas such as shopping malls, supermarkets, libraries, warehouses and other locations for goods protection. This dissertation originates from a horizontal project on RF EAS systems antiinterference design and hardware & software implementation. Performances of EAS system are mainly focused on three aspects: detection rate, false alarm rate and detection distance. In general,factors that can probably contribute to improving the performances mentioned above are as follows:hardware configuration design, environment noise, artificial factors, system software design and anti-interference techniques. This dissertation aims to design and implement an integrated EAS system which establishes the foundation of doing a research on anti-interference detection technique to improve system performance. Specific works accomplished are as follows:Firstly, this dissertation presents a superior performance and lower cost hardware design under TI DSP28335 and AD9834 architecture for the first time. In addition, this design adopts dual-antennas, integrated transceiver EAS system with lower cost, easier installation and higher performance which is quite different from the traditional ones.Secondly, theoretical analysis has been completed on characteristics of tag signal including periodicity, symmetry, amplitude and gradual changing property. Meanwhile, several detection methods have been given separately. Researches on anti-interference detection technique cannot be separated from analysis of interference and noise. Therefore, this dissertation is focused on the analysis of random noise, pulse interference, power interference and artificial factors from both time and frequency domains. Accordingly, characteristics, sources and deterioration degree of interference can be definitely known and served as theoretical basis and data support for the follow-up study of anti-interference techniques.Finally, relevant technical literature about EAS design has been exhaustively introduced in this dissertation. We propose a synthetical detection method including Variable Window Width Sliding Average Filtering(VWWSAF) algorithm, Two-cycle Diluted Stratified Auto-Correlation Coefficient(TDSACC) technique and Frequency Domain Partial Trimming(FDPT) method.VWWSAF algorithm has a great inhibitory effect on pulse interference. TDSACC technique can successfully avoid the influence of random noise. Other interference in frequency domain can be deeply weakened by FDPT method. Ultimately achieve the target of improving the ability of taganti-interference detection.