METHOD AND SYSTEM FOR NEAR FIELD COMMUNICATION

摘要

The invention involves a method and system for short range communications. The method includes: a card reader transmitting a low-frequency time-varying magnetic field signal, the frequency of which is equal to or less than a highest frequency f0 at which the system does not require calibration for functioning, and the signal carrying identifier information of the card reader; a mobile radio frequency device receiving and detecting the low-frequency signal, and magnifying it to be a voltage signal, and determining whether a terminal enters an effective distance interval; if the voltage signal is greater than or equal to a voltage threshold Vt, then the terminal has entered the distance interval for effective card swiping, and obtaining the identifier information of the card reader, and transmitting its own identifier information together with the identifier information of the card reader to the card reader through a radio frequency channel; the card reader receiving the transmitted information, and comparing whether the identifier information in the transmitted information is consistent with the identifier information of its own, if it is consistent, then performing a card swiping transaction with the mobile radio frequency device through the radio frequency channel. This invention realizes that the data communicating distance between a radio frequency communication terminal including a mobile radio frequency device and a card reader can be controlled reliably within a specified range, and that the terminal needs not to be calibrated.