SLAA907D September   2019  – December 2021 PGA450-Q1 , PGA460 , PGA460-Q1 , TDC1000 , TDC1000-Q1 , TDC1011 , TDC1011-Q1 , TUSS4440 , TUSS4470

 

  1.   Trademarks
  2. 1What is Ultrasonic Time-of-Flight Sensing?
    1. 1.1 Principles of Ultrasound
    2. 1.2 Why Use Ultrasonic Sensing?
    3. 1.3 How Does Ultrasound Compare to Other Sensing Technologies?
    4. 1.4 Typical Ultrasonic-Sensing Applications
  3. 2Ultrasonic System Considerations
    1. 2.1 Introduction to the Ultrasonic System
    2. 2.2 The Ultrasonic Echo and Signal Processing
    3. 2.3 Transducer Types
    4. 2.4 Transducer Topologies
    5. 2.5 Transducer Frequencies
    6. 2.6 Transducer Drive (Transformer Drive & Direct Drive) and Current Limit
    7. 2.7 Pulse Count
    8. 2.8 Minimum Detection Range
  4. 3What Factors Influence Ultrasonic Sensing?
    1. 3.1 Transmission Medium
    2. 3.2 Acoustic Impedance
    3. 3.3 Radar Cross Section
    4. 3.4 Ambient Conditions (Temperature, Humidity, Debris)
    5. 3.5 Device Selection
  5. 4Additional Resources
  6. 5Revision History

3.1 Transmission Medium

Transmission properties, and the speed of sound, change across different mediums. An ultrasonic sensor is optimized for sound wave propagation through air, liquids, or solids, but rarely for more than one type of transmission medium. Ultrasonic attenuation in the air increases as a function of frequency, so air-coupled ultrasonic applications are limited to frequencies below 500 kHz. Liquid and solid applications can use transducers in the low MHz range for high-accuracy applications.

GUID-7418AF69-1E98-48F6-9EC0-C3062F8131EB-low.pngFigure 3-1 Speed of Sound Through Different Media