Wireless SAW Interrogator and Sensor System

Wireless, passive, Surface Acoustic Wave (SAW), Orthogonal Frequency Coded (OFC) temperature sensors, operating in a multi-sensor environment, developed at the University of Central Florida (UCF) have been successfully interrogated wirelessly at a distances ranging from 7 to 21 feet with a transceiver system developed by Mnemonics, Inc (MNI). The proposed innovation adds a coherent detection capability to the interrogator receiver, allowing the phase of the received signal to be measured. As is done in GPS signal processing, the phase information allows precise measurement of range (from the interrogator to sensor) as well as motion, and if multiple antennas are used, angle of arrival (i.e. direction) can also be sensed. The investigation will include optimizing waveforms for the new measurement capabilities and will extend the detection range well beyond the 21 feet. Other objectives are to develop a compact integrated sensor and antenna, synchronize timing and phase in a multiple interrogator network and improve RF performance on both the transmit and receive side of the interrogator. The proposed interrogator is based on a quadrature receiver technique and will also include wireless backhaul for instantaneous distribution of measurement data. The proposed interrogator and SAW sensors are to operate at the 915 MHz frequency band. The proposed system will be used in a broad range of NASA, as well as commercial applications.