Intercepting UHF RFID signals through synchronous detection

Recently, augmented ultrahigh frequency radio-frequency identification (UHF RFID) systems have been developed, and they contain additional components that can detect a tag’s backscattered response and use this information for the localization of the tag and other applications. The methods currently employed either have poor performance because the detection of the tag’s response is based on envelope detection or are costly because they are based on software-defined radio. The solution proposed in the paper is to use a method called synchronous detection to intercept tag signals. Using synchronous detection, we were able to use a conventional UHF RFID reader integrated circuit for the method, leading to a cost-effective, high-performance solution. We performed an analysis of its read rate and read range performance. The analysis showed that our receiver is capable of receiving tag signals with a read rate of 50% for passive and 66% for semi-passive tags at a 1-m distance between the tag and the receiver and is capable of receiving tag signals at a maximum distance between the tag and the receiver of 3.25 m for passive and 5.5 m for semi-passive tags, with the reader being within 8 m of the receiver. This augmented RFID system has a potential to facilitate localization and prevent the cross-read problem in RFID-based portals. In addition, it can be used as a protocol analyzer as well as a component of future Internet of Things.