Convolution and Time Inversion Using Parametric Interactions of Acoustic Surface Waves

We report on the observation of acoustic convolution, time inversion, and electronically variable delay in real time using 105- and 220-MHz surface acoustic waves in YZ-cut LiNbO3 delay rods. The time inversion is a special case of correlation, where a short ``pip'' pulse will create a reflection in time for the injected input signal pulse. The conversion losses in the processing were 64–74 dB.