电子与通信工程专业英语Unit 18 Integrating RFID on Event-based Hemispheric Imaging for Internet of Things-修改.ppt

电子与通信工程专业英语Unit 18 Integrating RFID on Event-based Hemispheric Imaging for Internet of Things
1．Introduction　　The remote activity monitoring across large environments, such as government facilities, public buildings or industrial environments in real time, is a prerequisite for various monitoring applications. Such activities can also prove a useful addition in assistive environments in smaller size spaces, like houses and offices. Modern video-based surveillance systems, which employ powerful real time analysis techniques, are widely deployed.
Two are the most important characteristics of an RFID system each encapsulating differences in range, data transfer and transmission under certain environmental conditions: 　　① the energy resources and computational capabilities of RFID tags and ② its operating frequency. According to the first characteristic, RFID tags are distinguished into passive and active, as well as their combinations.
Active tags incorporate a battery and can transmit signals autonomously, over a long operation range with high performance but they are expensive and usually have a large size. On the other hand, passive tags require an external source to provoke signal transmission, which is acquired using either inductive coupling or electromagnetic capture and they communicate with the reader by utilizing load modulation or electromagnetic backscatter.