Detection, identification, location, and remote sensing using SAW RFID sensor tags

We consider the problem of simultaneous detection, identification, location estimation, and remote sensing for multiple objects in an environment. In particular, we describe the design and performance of a system capable of simultaneously detecting the presence of multiple objects, identifying each object, and acquiring both a low-resolution estimate of location and a high-resolution estimate of temperature for each object based on wireless interrogation of passive surface acoustic wave (SAW) radio-frequency identification (RFID) sensor tags affixed to each object. The system is being studied for application on the lunar surface as well as for terrestrial remote sensing applications such as pre-launch monitoring and testing of spacecraft on the launch pad and monitoring of test facilities. The system utilizes a digitally beam-formed planar receiving antenna array to extend range and provide direction-of-arrival information coupled with an approximate maximum-likelihood signal processing algorithm to provide near-optimal estimation of both range and temperature. We examine the theoretical performance characteristics of the system and compare the theoretical results with results obtained from controlled laboratory experiments.