The Study Of Low Frequency Wakeup Technique In Intelligent Park Management Based On The ZigBee Network

With the quick increment of the vehicle, many vehicles cause the traffic jam because of the lack of parking space and the low efficiency of park management, especially in the prosperous business streets of the big cities. Though a few parks can realize automatic management using passive RF Card, many parks still adopt the manual mode. Because the passive RF Card has much shorter working distance, it can not improve the efficiency of charge. And the information of vehicles is not inquired by using this system, especially in which the parking guidance can not be implemented. So, a kind of intelligent park management system, which satisfies the function of no parking charge, real-time parking space detection and inquiry of the vehicle information, is expected to the market.Zigbee is a new technique, which has advantages of low rate, low cost, low power consumption, low complexity and good security. Therefore Zigbee technique is becoming a hotpot of the wireless communications field. In order to meet the demand of markets, this thesis designs a kind of intelligent park management system based on Zigbee network to realize the above functions.The system is composed of entrance sub-system, park sub-system, park guide sub-system, export sub-system, and control center. All the sub-systems can communicate with each other by Zigbee network. The park sub-system includes master,reader and tag, and they also communicate by Zigbee network.The thesis mainly finished the design of reader and tag in park sub-system, the research is as follows:1. We design the ultrasonic circuit for measuring distance and realize the function of park space detection.2. We design the low frequency wakeup circuit, which is composed of the transmitting circuit and the receiving circuit, to solve the power consumption problem of the tag. The transmitting circuit is mainly composed of AS4420 and the serial resonance circuit, and the receiving circuit is mainly composed of ATA5283 and the parallel resonance circuit.3. We finish the program of the tag, which can identify the code of the low frequency wakeup circuit and transmit the data, to resolve the interference efficiently.4. By simplifying the protocol stack, the program is optimized and the number of code is decreased. The tag can adopt a low cost MCU C8051F410, and the efficiency and stability of the tag is also improved.At the end, we finish two kinds of test, including the covering area of the low frequency magnetic field and the orientation problem when the tag is waked. Conclusions show that the effect of the low frequency wakeup is all right and it can meet the demand of markets...