Understanding How Ultrasonic Sensors Work


Ultrasonic sensing is one of the best ways to sense proximity and detect levels with high reliability.

Our technical support gets emails all of the time about how our sensors work and what environments our sensors work (or don’t work) in.

This guide was created as an introduction to ultrasonic sensing, it’s principles, and how ultrasonic sensors work in your applications.


At a top level, you need to know what an ultrasonic sensor is…

What is an ultrasonic sensor?

An ultrasonic sensor is an instrument that measures the distance to an object using ultrasonic sound waves.

An ultrasonic sensor uses a transducer to send and receive ultrasonic pulses that relay back information about an object’s proximity.  

High-frequency sound waves reflect from boundaries to produce distinct echo patterns.


How Ultrasonic Sensors Work.

Ultrasonic sound vibrates at a frequency above the range of human hearing.  

Transducers are the microphones used to receive and send the ultrasonic sound.

Our ultrasonic sensors, like many others, use a single transducer to send a pulse and to receive the echo.  The sensor determines the distance to a target by measuring time lapses between the sending and receiving of the ultrasonic pulse.Basic Sonar Illustration


Why use an Ultrasonic Sensor?

Ultrasound is reliable in any lighting environment and can be used inside or outside.  Ultrasonic sensors can handle collision avoidance for a robot, and being moved often, as long as it isn’t too fast.  

Ultrasonics are so widely used, they can be reliably implemented in grain bin sensing applications, water level sensing, drone applications and sensing cars at your local drive-thru restaurant or bank.

Ultrasonic rangefinders are commonly used as devices to detect a collision.  

Ultrasonic Sensors are best used in the non-contact detection of:

  • Presence
  • Level
  • Position
  • Distance

Non-contact sensors are also referred to as proximity sensors.

Ultrasonics are Independent of:

  • Light
  • Smoke
  • Dust
  • Color
  • Material (except for soft surfaces, i.e. wool, because the surface absorbs the ultrasonic sound wave and doesn’t reflect sound.)


Long range detection of targets with varied surface properties.


Ultrasonic sensors are superior to infrared sensors because they aren’t affected by smoke or black materials, however, soft materials which don’t reflect the sonar (ultrasonic) waves very well may cause issues. It’s not a perfect system, but it’s good and reliable.


Applications Involving Ultrasonic Detection:

    • Ultrasonic Distance Measurement
      • Ex. Distance measurement would be applied in a garage parking application, sensing when a vehicle is pulled completely into a garage.
    • Ultrasonic Obstacle Detection
      • Our UAV Sensors for Drones as well as our proximity sensors that are used for robots are for obstacle detection.

Ultrasonic sensors are a reliable, cost-effective solution for distance sensing, level, and obstacle detection.

Once you understand how ultrasonic sensors work and what ultrasonic technology is perfect for and not so good for, you can make a more educated decision on the right sensor system for your application.  

Take a look at our patent pending solution for sensing cargo in 53′ trailers to detect the fullness or absence.  Read about the Trailer Cargo Sensor.


Review our product catalog and contact our Technical Support Team by clicking the button below to get help selecting a sensor.


Understanding How Ultrasonic Sensors Work
Article Name
Understanding How Ultrasonic Sensors Work
If you're considering using ultrasonic technology to sense in your project there are things you need to understand. This article provides information on how ultrasonic sensors work.
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MaxBotix Inc.
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