Texas Instruments Incorporated
Time-varying template for improved short-distance performance in coded ultrasonic ranging

Abstract:

Ultrasonic ranging systems and methods that emit coded bursts and correlate transduced acoustical echoes of the bursts with a receive template characterizing a burst code to determine time-of-flight information use receive templates of time-variable length to improve short-range object detection. The template length is based on a time index measured from the start of the burst emission. The detection can account for a dead zone of transducer ringing following a burst. A time-variable gain that is also based on the time index can be applied to the correlated signal. The length and gain can be adjusted with reduced temporal frequency to reduce computation cost.