Device-specific calibration for ultrasound emissions

Abstract

Techniques for calibrating user devices to account for device-specific factors that can affect the user devices' abilities to detect user movement. User devices detect user movement by emitting ultrasonic signals, and characterizing changes in signal characteristics of reflections of the ultrasonic signals off the person caused by the movement of the person. Device-specific factors may negatively affect the ability of the user devices to detect user movement. To account for these factors, device-specific frequency responses for each device may be determined across bandwidths in an ultrasonic frequency range, and the device-specific calibration data may be stored on each user device. Upon being placed in user environments, the user devices emit ultrasonic sweep signals that span the different bandwidths in the ultrasonic frequency range to determine environmental factors. The user devices may use the device-specific and environmental factors to determine optimal carrier frequencies and gain values for subsequent ultrasonic signal transmissions.