Patent ID: 8390169

Claim:
An ultrasonic system, comprising: an ultrasonic device configured to impart ultrasonic energy to tissue; and an ultrasonic generator configured to supply power to the ultrasonic device, the ultrasonic generator comprising: a controllable drive signal generator configured to provide a drive signal; a controllable noise signal generator configured to provide a noise signal, wherein the noise signal is a pseudo random noise sequence; an adder configured to combine the drive signal and the noise signal; an amplifier having a gain, the amplifier configured to amplify the combined drive signal and noise signal and provide the amplified signal to the ultrasonic device; and a controller configured to: receive an output signal from the ultrasonic device and the noise signal from the noise signal generator, calculate a transfer function estimate based on the output signal and the noise signal, adjust the drive signal generator based on the calculated transfer function estimate, and determine a phase difference by time aligning a noise signal in the output signal with the noise signal provided by the noise generator.