Design And Implementation Of Unconscious Entrance Guard’s System Based On Low Frequency

With the propelling of the new plan of College Entrance examination sites reform,new course selection model has made it a general trend to implement class-based teaching in high schools.Class attendance problem needs to be solved urgently.To deal with it,schools hope to introduce intelligent entrance guard’s systems to detect students’ location in and out of the classroom.Such systems available now have problems of slow detection efficiency,poor accuracy and insufficient endurance of attendance tag cards.Therefore,efficient,accurate,high-endurance and reliable unconscious entrance guard’s systems are badly needed.In response to above requirements,this thesis designs a unconscious entrance guard’s systems based on low frequency,which breaks through the precise entry and exit positioning technology of the access area personnel and the rapid positioning information exchange technology.Meanwhile,low power consumption,high efficiency and Accurate in and out detection for the dense population in the access area are realized.The main work of this thesis includes:1.Aiming at the problem of inaccurate positioning caused by electromagnetic interference of metal doors in the bayonet area and other complex environment,a fusion positioning algorithm based on RSSI ranging error correction is proposed,which could realize accurate positioning of people carrying cards in and out of the access area.Compared with the low-frequency RSSI positioning algorithm,it solves problem of blind spots in the middle area of the access.Also,it greatly improves the accuracy of in-andout positioning compared with maximum likelihood estimation and triangular centroid positioning algorithms.2.Aiming at the problem of location information communication conflict between bayonet base station and numerous tag cards,a BTF air interface communication protocol is designed.Tag cards wake-up conflict is solved by time division multiple access and low-frequency frame structure optimization.While tag cards reading conflict is solved by frequency division and time division multiple access,combining the frame time slot ALOHA method to configure the tag network access time slot and avoid competition.Rapid exchange of location information in the bayonet area is realized.3.To meet the needs of schools’ requirements for the entrance guard’s system,the overall plan of the system is designed and feasibility demonstration is proved,including system architecture design,detection process design,software and hardware design of each module of the detection system,communication protocol and positioning algorithm design.Finally the unconscious entrance guard’s systems prototype is developed,with efficient detection of the dense population in the access area realized.In above work,field experiments of functional testing and performance testing in real classroom bayonet environment are implemented,fully verifying the feasibility of the prototype system.It could achieve more than 95% accuracy by personnel entry and exit detection of 400 tests.The tag card life exceeds more than 6 months.The system response time is less than 500 ms,which is of great significance for detecting students’ attendance in new college entrance examination school.In addition,in response to the requirements of the mine asset management project of Sixiangzhi New Technology Co.,Ltd,field tests are carried out and achieve the same effect as above.It is also of great value to solve the problem of equipment management confusion in the coal mining field.