2-CHANNEL SAW SENSOR SIGNAL-TRANSMISSION SYSTEM

We present a wireless signal-transmission system for surface acoustic wave (SAW) sensor signals. Using a new signal-processing method, two c hannels can be transmitted in parallel. Each channel is transferring t he frequency and the attenuation of a SAW delay line sensor. The signa l processing is combined with a correlation technique known as the spr ead spectrum technique. Its advantages are low transmission power and high rejection against jamming and interference. As a first step towar ds integration of acoustic and electronic components, we have prepared the SAW coding and decoding devices on GaAs. We describe a 10 m dista nce transmission with a minimum power of 10 nW and discuss the capabil ities of the system.