The Multi-function Door Access Control Apparatus Hardware Design

• Main Authors: Yu-Ping Fang, 房育平
• Other Authors: Yun-Shih Chou
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/89216559767547747841

碩士 === 聖約翰科技大學 === 電子工程系碩士在職專班 === 102 === In this paper it mainly investigates the development of the measures of suppressing the electromagnetic interference and in the improvement of induction strength of RFID antenna in the multi-functional access and security apparatus in the modern smart buildings. Due to the PCB area of the RFID antenna module has been limited by the structure of the multi-functional access and security apparatus it results in the inconformity between the antenna, which fabricated from wiring in the limited area, and the RFID module. In this paper we discuss the design of increasing the antenna reflecting area to improve the electromagnetic induction strength of RFID antenna and also to modify the PCB stack up and layout to greatly improve the output amplitude of its working pulse from 4.48 V to 9.36 V to effectively increase electromagnetic output amplitude so to achieve the effect of improving sensing distance. In this thesis it investigates various methods of preventing multi-functional door access control apparatus from electromagnetic radiation interference. Four methods are investigated: 1) the use of metal mechanism to reduce the grounding impedance between the power system and the modules, e.g. the electromagnetic interference can be reduced by 3 to 10 dB in the 30 MHz to 300 MHz frequency range; 2) the change of cable connection location from the connection through and above the circuit board to the connection from the peripheral of the circuit board that the electromagnetic interference can be reduced by 9 dB at 175 MHz; 3) the modification of the filter circuit of the Pixel clock to remove the capacitor in the circuit to make the electromagnetic interference reduction by 3 dB at 225 MHz; 4) the modification of the ARM9 PLL circuit elements to ferrite beads that the electromagnetic interference can be reduced by 10 to 15 dB in 300 MHz to 1 GHz frequency range. By using above methods and processes can suppress the electromagnetic interference level in the printed circuit board below the threshold level in 30 MHz – 1 GHz range products. The consideration and results of this study can provide valuable design and development references for the door access control industry to shorten its product development and the electromagnetic interference reduction schedules.