By receiving the ultrasonic waves generated by the tested equipment, it is converted into sounds that can be heard by human ears and digital signals that can be received and analyzed by the computer.
Analyze and judge. Similar to radio, radio converts received electromagnetic waves into sound waves that can be heard by human ears.
What is ultrasound?
Sound wave is the propagation form of mechanical vibration state (or energy) of an object. The so-called vibration refers to the back-and-forth motion of particles of matter near their equilibrium positions.
Exercise. For example, after the drum head is hit, it vibrates up and down, and this vibration state propagates in all directions through the medium, which is sound wave.
The frequency of ultrasonic vibration is above 20KHz, which exceeds the upper limit of human hearing (20000Hz). People call this inaudible sound wave ultrasound.
Wave. It usually propagates in elastic medium in the form of longitudinal wave, which is a form of energy transfer. It is characterized by high ultrasonic frequency and short wave length.
Propagation along a straight line within a certain distance has good beam and directivity.
What produces ultrasonic waves:
Ultrasonic waves are generated where high-frequency vibrations are generated. For example, when people talk and breathe, they will not only produce sound waves, but also produce some ultrasonic waves.
Exhaled gas molecules collide with air molecules to generate ultrasonic waves. Air leakage in trachea, tire, valve, valve cavitation and gear malfunction.
Corona discharge will produce ultrasonic waves. Ultrasound is ubiquitous in life and production.