rfid技術(shù)外文文獻翻譯-其他專業(yè)-在線瀏覽
2025-03-24 06:50本頁面
【正文】 on sidechannels which are located directly below and above the frequency of the continuous wave. 1. Energy Sources We distinguish 3 types of RFID tags in relation to power or energy: Passive, Semipassive, Active Passive tags do not have an internal power source, and they therefore rely on the power induced by the reader. This means that the reader has to keep up its field until the transaction is pleted. Because of the lack of a battery, these tags are the smallest and cheapest tags available。s range can be tens of meters, making it ideal for locating objects or serving as landmark points. The lifetime is up to 5 years. 2. Frequency Bands RFID tags fall into three regions in respect to frequency: Low frequency (LF, 30 500kHz), High frequency (), Ultra high frequency (UHF, 850 950MHz, , ) Low frequency tags are cheaper than any of the higher frequency tags. They are fast enough for most applications, however for larger amounts of data the time a tag has to stay in a readers range will increase. Another advantage is that low frequency tags are least affected by the presence of fluids or metal. The disadvantage of such tags is their short reading range. The most mon frequencies used for low frequency tags are kHz and kHz. High frequency tags have higher transmission rates and ranges but also cost more than LF tags. Smart tags are the most mon member of this group and they work at . UHF tags have the highest range of all tags. It ranges from 36 meters for passive tags and 30+ meters for active tags. In addition the transmission rate is also very high, which allows to read a single tag in a very short time. This feature is important where tagged entities are moving with a high speed and remain only for a short time in a readers range. UHF tags are also more expensive than any other tag and are severely affected by fluids and metal. Those properties make UHF mostly useful in automated toll collection systems. Typical frequencies are 868MHz (Europe), 915MHz (USA), 950MHz (Japan), and for LF and HF tags are license exempt and can be used worldwide。 however, the system would behave in exactly the same way if tags were used). When the reader scans the barcode, the application
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