近年來，自動識別技術發展迅速，尤其是隨著電子技術的高速發展和制造技術的不斷進步，采用無線電和雷達技術實現的射頻識別技術（RFID-radio frequency identification）發展極為迅速，在物流系統、商業貿易、門禁防盜、識別技術和醫學應用等領域中得到了極為廣泛地支持和應用。
射頻識別是一種非接觸式的自動識別技術，它通過射頻信號自動識別目標對象并獲取相關數據，識別工作無須人工干預，作為條形碼的無線版本，RFID技術具有條形碼所不具備的防水、防磁、耐高溫、使用壽命長、讀取距離大、標簽上數據可以加密、存儲數據容量更大、存儲信息更改自如等優點，其應用將給零售、物流等產業帶來革命性變化。在國內外射頻式IC卡已被廣泛應用于公交、地鐵等眾多的收費系統。
本文章就是針對非接觸式射頻卡設計的計費系統。文章主要介紹了基于射頻識別技術所制作的采用4MHz載波的閱讀器與應答器的設計方法和工作原理，以及應答器與閱讀器上一對單片機通信的軟件實現。
關鍵詞： 射頻識別 非接觸 閱讀器 應答器 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
