A 915 Mhz Saw Sensor Correlator System

Previous work has been presented on passive wireless surface-acoustic-wave (SAW) sensors using the orthogonal frequency coding (OFC) technique ( Malocha , Proc. Int. Soc. Opt. Eng. (SPIE), Aug. 23-27, 2004, vol. 2, pp. 1082-1085), Pavlina , Proc. IEEE Int. Conf. RFID, 2009, pp. 110-115). This paper will present a SAW sensor correlator system and its key operational parameters. Description of the radio frequency (RF) transceiver system and the OFC SAW temperature sensors is provided for parameter characterization. The system is based on a software radio approach and an analysis of the analog-to-digital converter (ADC) parameters and receiver noise in temperature extraction is presented. Initial experimental results for a four-sensor system operating over a 280° range are given. © 2011 IEEE

Ultra-Wideband Communication System Prototype Using Orthogonal Frequency Coded Saw Correlators

This paper presents preliminary ultra-wideband (UWB) communication system results utilizing orthogonal frequency coded SAW correlators. Orthogonal frequency coding (OFC) and pseudo-noise (PN) coding provides a means for spread-spectrum UWB. The use of OFC spectrally spreads a PN sequence beyond that of CDMA; allowing for improved correlation gain. The transceiver approach is still very similar to that of the CDMA approach, but provides greater code diversity. Use of SAW correlators eliminates many of the costly components that are typically needed in the intermediate frequency (IF) section in the transmitter and receiver, and greatly reduces the signal processing requirements. Development and results of an experimental prototype system with center frequency of 250 MHz are presented. The prototype system is configured using modular RF components and benchtop pulse generator and frequency source. The SAW correlation filters used in the test setup were designed using 7 chip frequencies within the transducer. The fractional bandwidth of approximately 29% was implemented to exceed the defined UWB specification. Discussion of the filter design and results are presented and are compared with packaged device measurements. A prototype UWB system using OFC SAW correlators is demonstrated in wired and wireless configurations. OFC-coded SAW filters are used for generation of a transmitted spreadspectrum UWB and matched filter correlated reception. Autocorrelation and cross-correlation system outputs are compared. The results demonstrate the feasibility of UWB SAW correlators for use in UWB communication transceivers. © 1986-2012 IEEE