近年来，自动识别技术发展迅速，尤其是随着电子技术的高速发展和制造技术的不断进步，采用无线电和雷达技术实现的射频识别技术（RFID-radio frequency identification）发展极为迅速，在物流系统、商业贸易、门禁防盗、识别技术和医学应用等领域中得到了极为广泛地支持和应用。
射频识别是一种非接触式的自动识别技术，它通过射频信号自动识别目标对象并获取相关数据，识别工作无须人工干预，作为条形码的无线版本，RFID技术具有条形码所不具备的防水、防磁、耐高温、使用寿命长、读取距离大、标签上数据可以加密、存储数据容量更大、存储信息更改自如等优点，其应用将给零售、物流等产业带来革命性变化。在国内外射频式IC卡已被广泛应用于公交、地铁等众多的收费系统。
本文章就是针对非接触式射频卡设计的计费系统。文章主要介绍了基于射频识别技术所制作的采用4MHz载波的阅读器与应答器的设计方法和工作原理，以及应答器与阅读器上一对单片机通信的软件实现。
关键词： 射频识别 非接触 阅读器 应答器 4MHz
Abstract
In recent years, the rapid development of automatic identification technology, especially with the rapid development of electronic and manufacturing technology. to achieve the RFID,using radio and radar technology - have developed very quickly, which got extremely extensive application and support in the logistics system, business trade, access to guard against theft, identification technology and application in the fields of medical . RFID is a non-contact automatic identification technology, which automatichally identifies targets through rf signal and gets access to relevant data. identification work doesn't need manual intervention. As the wireless version of bar code technology, RFID has the advantages of waterproof, magnetic influence, high temperature resistance, long service life, label data encryption, larger capacity, free stored information change.And the application will give retail, logistics and other industries with revolutionary change. At home and abroad, rf type IC card has been widely applied in numerous arear such as transit, metro system. This article is designed for the contactless rf CARDS charging system, which mainly introduces working principle and design method of the reader and the transponder based on rfid technology made by 4MHz carrier, and with a single-chip communication software realization.
Keyword：Radio Frequency Identification non-contact reader transponder 4MHz
