US Patent 8707785 On-board ultrasonic frequency spectrum and image generation

A portable apparatus for determining testing the condition of a machine or device using ultrasonic signals with an array of ultrasonic sensors for receiving an ultrasonic signal transmitted from the machine or device. The apparatus possesses a heterodyne circuit coupled to receive the output signals from the ultrasonic sensors and convert the output signals to a heterodyned audio signal to be analyzed via a digital spectrum analyzer integral to the portable apparatus. The digital spectrum analyzer performs real-time fast fourier transformations on the heterodyned audio signal. After analyzing the signals, the hand held device uses a variety of audiovisual cues to direct a user to portions of the machine in need of repair or monitoring.