声表面波射频标签码容量的最大化
The maximization of code capability of surface acoustic wave radio frequency identification
-
摘要: 声表面波标签是一种不使用集成电路芯片的射频识别技术。由于其与半导体射频标签在原理上的本质区别,在若于特殊场合下具有独特的优势。声表面波标签的码容量通常很难满足实际应用的需求,成为限制其广泛应用的主要原因。提出了一种设计声表面波射频标签系统的新方法,从以下两方面增大码容量:(1)根据实际系统的误差概率和所要求的可靠性,最佳地决定系统设计的分辨精度;(2)采用反射脉冲的时延间隔代替反射脉冲的绝对时延位置来表述该脉冲代表的码片值,从而避免了人为分组,在一定空间内最大可能地增大了码容量。以中心频率922.5 MHz、带宽5 MHz的射频标签为例,在8 mm长的128°YX-LiNbO3压电基片上,制作了码容量超过三下万的系统。该系统包括温度校准,在识别标签的同时并能测出温度,精度为0.5℃。Abstract: Surface Acoustic Wave(SAW) Radio Frequency Identification(RFID) has its advantages over IC based RFID,but it has difficulties to possess the code capacity large enough for most practical usage.Especially,in the frequency band of 922.5 MHz,the permitted bandwidth is only 5 MHz,which restricts the reflectors separated each other distantly,as the results,the code capacity becomes much less in the same dimension of the chip.In order to break through it,in the paper,we report a new system,which enables one to fabricate a tag with code capacity 3.5×107 within a chip length of 8 mm.The result demonstrates a bright prospect of SAW RFID for wide applications.
下载: