What is Ultrasonic Sensor: Working Principle & Applications

What is Ultrasonic Sensor: Working Principle & Applications


Are you looking for an accurate, reliable, and cost-effective way to measure the distance, level, or presence of an object?  If the answer is Yes! Consider an ultrasonic sensor. This blog post covers what it is, the principle of working, how it is used and its applications Ready to learn more?  If you want to learn more about these amazing devices, then keep reading!

What is an Ultrasonic Sensor?

The Ultrasonic Sensor is an electronic device which measures distances by sending out sound waves and collecting the returning echoes. It can measure items up to 4.5 meters away, making it a versatile tool for measuring both short and long distances accurately without contact with the target item - essential in many applications such as obstacle avoidance systems in robotics or autonomous vehicles. The sensor features adjustable pulse widths, allowing for higher resolution measurements when set at lower levels though this comes at cost of range accuracy diminishing as a result; however due to its affordability compared other forms of distance sensing technologies makes it incredibly suitable where budget constraints are paramount factor within projects evaluating solutions using ultrasonics technology.


What is Ultrasonic Sensor


Ultrasonic sensors are used as proximity sensors. They can be found in parking technology and anti-collision safety systems. Ultrasonic sensors are also used in robotic obstacle detection systems and manufacturing engineering. Compared to infrared (IR) sensors in proximity sensing applications, ultrasonic sensors are less susceptible to interference from smoke, gases, and other airborne particles (although the physical component is subject to variables such as heat). 


Ultrasonic sensors are also used as level sensors to detect, monitor, and control liquid levels in closed vessels (such as chemical plant drums). Most notably, ultrasound technology has enabled the medical industry to image internal organs, identify tumours, and ensure the health of babies in the womb.

Principle of Ultrasonic Sensor

The principle of ultrasonic rangefinders is to measure the time it takes 

the signal sent by a transmitter and propagated back to the receiver. As the name implies ultrasonic sensor operates on ultrasonic frequencies. Frequencies beyond our hearing range are known as ultrasonic frequencies. Those frequencies are above 20k Hertz. 


They are the all-rounders of sensor technology and can be used in any industrial application. There are several types of objects that can be detected, including solids, liquids, granules, and powders. They reliably detect transparent or glossy objects, as well as objects whose colors change. 


Principle of ultrasonic sensor

How Ultrasonic Sensor Works?

An ultrasonic sensor is an electronic device that measures the distance to an object by emitting ultrasonic waves and converting the reflected sound into electrical signals. Ultrasound travels faster than audible sound (that is, sound that humans can hear). An ultrasonic sensor consists of two main components: a transmitter (which uses a piezoelectric crystal to emit sound) and a receiver.


While some sensors use separate sound emitters and receivers, it is also feasible to merge both functions into a single device by using an ultrasonic element to switch between sending and receiving signals in a continuous cycle. The transmitter of the module transmits an ultrasonic sound. This sound will be reflected if an object is present in front of the ultrasonic sensor. The reflected sound is received by the receiver present in the same module. An ultrasonic signal is propagated by a wave at an angle of 30°. The above-depicted Figure illustrates how the ultrasonic signal propagates from the transmitter. Measuring angles should be at least 15° for maximum accuracy. In this case, external objects that fall under this measurement angle interfere with determining the distance to the desired object.


The distance is determined by measuring the travel time of ultrasonic sound and its speed.

Distance = Time x Speed of sound / 2

Reflection of the sensing sound varies with configuration, for example


How ultrasonic sensor works


(A) Flat objects: liquid, box, plastic sheet,

(B) Columnar objects: can, bottle, the human body,

(C) Granular objects: ores, rock, coal, coke, plastic pellet,


To generate the ultrasonic sound, need to trigger the trigger pin as high for a minimum of 10us. Then the module will start sending 8 sonic burst ultrasounds from the module at 40 Khz. It will receive by the receiver called Echo pin and it will calculate the output time to measure the distance.



To prevent mutual interference between Ultrasonic Sensors, the synchronous operation can be used by emitting the ultrasonic waves from each Sensor simultaneously.



  • Supply voltage +5 V;
  • Consumption in silent mode 2 mA;
  • Consumption at work of 15 mA;
  • Measurement range - 2 to 400 cm;
  • Effective measuring angle 15°;
  • The dimensions are 45×20×15 mm.

How are Ultrasonic Sensors used?

With microcontroller platforms like the Raspberry Pi, ARM, PIC, Arduino, Beagle Board, and many more, our ultrasonic proximity level and distance sensors are often employed. Ultrasonic sensors will send sound waves in the direction of the target and calculate its distance by timing how long it takes for the waves to bounce back to the sensor. In addition, to collision avoidance systems also employ ultrasonic sensors.


Here, implemented ultrasonic sensor with Arduino. Before interfacing let us see the pinout of the ultrasonic sensor,


Four pins in the ultrasonic sensor


power supply +5 V


Common ground

Trigger pin

To start the sensor

Eco pin

Receive the signal

Use multiple sensors to avoid interference

When using multiple sensors in an application, it is important to connect them in a way that avoids problems such as crosstalk and other interference. 


It is important to keep the front of the ultrasonic transducer clear to avoid interference with the ultrasonic signal from the sensor.

Check out our complete guide on Arduino Interfacing with Ultrasonic Sensor

Advantages of Ultrasonic Sensors

  1. Ultrasonic sensors are an excellent way to measure the distance, speed and position of objects. They offer superior accuracy compared to traditional technologies such as lasers or infrared sensors.
  2. The ultrasonic wave is generated through a transducer that sends out high-frequency sound waves which travel faster than the speed of light due to their higher frequency range (ultrasonics is in the kilohertz range).
  3. These sensors enable manufacturers and engineers for detailed detection over wide ranges with minimal complexity involved when setting up certain systems; they can even detect objects at distances greater than 200m away accurately!
  4. Ultrasonic sensors also do not rely on visible light like other types of technology so they can be used indoors/outdoors without worrying about environmental conditions affecting performance levels - this makes them ideal for use in dark areas or lowlight situations where visibility would otherwise be compromised by regular sensing techniques
  5. These devices have self-diagnostics capabilities allowing users quick access to system status by checking errors & fault codes and reading back calibration parameters, thus providing easy maintenance routines.
  6. With no external power source needed, these types of tools operate more reliably with less downtime thus leading to improved productivity levels across applications relying heavily on its usage ranging from robotics automation industrial monitoring security surveillance activities etc,.

Applications of Ultrasonic Sensor

Ultrasonic Anemometers:

Anemometers are often used in weather stations because they efficiently detect wind speed and direction. 2D anemometers can only measure the horizontal component of wind speed and direction, while 3D anemometers can also measure the vertical component of wind. 


Ultrasonic anemometers can not only measure wind speed and direction, but also temperature. This is because the ultrasonic velocity is affected by temperature changes independently of pressure changes. Temperature is calculated by measuring the ultrasonic velocity change.

Tide gauge:

It is used to monitor sea levels and detects tides, storm surges, tsunamis, swells and other coastal processes. Tide gauges can detect water levels in real-time using ultrasonic sensors. Meters are often linked to an online database where records are kept, and the system can trigger alarms if dangerous situations occur.

Tank level:

Measuring the liquid level in a tank is like a level meter. However, in this case, the fluid may be freshwater, corrosive chemicals, or flammable fluids. In contrast to optical sensors and float switches, ultrasonic sensors are not in contact with liquids, which means less corrosion.

Web-guiding systems:

The purpose is to make sure the material is placed correctly. If the material is misaligned, the system mechanically moves the material back into the machine path. Ultrasonic sensors are well suited for web guiding, as the process requires non-contact, fast and efficient functionality.

UAV navigation:

Unmanned Aerial Vehicles (UAVs) (or drones) typically use ultrasonic sensors to monitor objects in their flight path and the UAV's distance from the ground. By automatically detecting safe distances, aircraft can avoid collisions. In addition, since the flight path changes in an instant, drone collision can be prevented by detecting the distance with ultrasonic waves.

Limitations of Ultrasonic Sensors

  1. Ultrasonic sensors have a limited range which makes them less effective when larger distances need to be covered or detected.
  2. They are prone to interference from other sources and can provide false readings due to these interferences, including reflections off of non-metallic objects that may not be correctly identified by the sensor’s recognition capabilities.
  3. Response times for ultrasonic sensing technology is relatively slow in comparison with some other types of distance measurement equipment such as infrared devices meaning they take longer periods of time before an accurate reading is provided back on screen, making it inconvenient where fast responses are needed immediately upon detection.
  4. High-density materials, extreme temperatures and small target surfaces are also unable to detect properly using ultra-sonic sensors since their performance gradually reduces under those conditions leading them to underestimate the actual values being measured within their vicinity environment.


In this blog post, we have learned ultrasonic sensors are an incredibly versatile technology with a wide range of practical applications. Understanding the principles and workings of these sensors can help you better appreciate the immense benefits they offer, from automation and security to medical and scientific research. By leveraging the power of ultrasonic sensors, you can unlock a whole new world of possibilities and take your projects to the next level. So why not explore the exciting world of ultrasonic sensors and see how they can transform your work today?


If you appreciate our work don't forget to share this post and leave your opinion in the comment box.


Please do check out other blog posts about Popular electronics


Make sure you check out our wide range of products and collections (we offer some exciting deals!)

Frequently Asked Questions

1. What is an ultrasonic sensor used for?

An ultrasonic sensor is a device that uses sound waves to detect the presence and proximity of objects. It sends out high-frequency sound waves that bounce off objects and then measures the time it takes for the sound waves to return. Ultrasonic sensors are commonly used in applications such as parking assist systems, robotics, and distance-measuring devices.

2. What are the advantages of ultrasonic sensor?

The ultrasonic sensors are just absolutely amazing! They have so many advantages, it's almost hard to keep track of them all! For one thing, they can detect the distance and position of objects with incredible accuracy, even in really tough environments like low-light or dusty ones. And get this, they don't even need to touch the object they're sensing, making them super easy to use in all kinds of different applications, from industrial automation to car safety systems.

3. What does an ultrasonic sensor do?

An ultrasonic sensor is an innovative technology that uses sound waves to detect motion and measure distances. It works by sending out high-frequency acoustic pulses, which are reflected by objects in the environment. The returning echoes are detected and measured accurately for a range of applications such as obstacle avoidance, flow measurement or security detection systems. As this method does not rely on light being visible between points, it can be used in dark environments making it extremely versatile and ideal for use indoors or outdoors where traditional technologies fail due to environmental conditions. By utilizing advanced parameters tuning algorithms combined with relevant data processing techniques we ensure excellent performance levels over time even under extreme operating conditions ensuring reliable results every time!

4. What is the basic principle of ultrasonic sensor?

Ultrasonic sensors are devices which measure the distance of an object by using sound waves. Ultrasonic waves travel in air at a known speed and when they hit a solid surface, part of them is reflected back to their source. The time difference between sending and receiving these ultrasonic pulses allows us to accurately calculate the distance from our position up to 5 meters away with resolutions within millimetres. This sensor technology can be found most commonly used in automotive park assist systems, burglar alarm detectors or presence sensing for automated machine operations. 

5. Is ultrasonic sensor analog or digital?

Ultrasonic sensors are an important part of many modern applications, so it's essential to know whether they're analog or digital. Ultrasonic sensors use sound waves that travel through air and measure the time needed for them to reach a target object and return back. They then convert this data into electrical signals which can be either analog or digital. Analog ultrasonic sensors generate continuous voltage output as measured by the echo ranging interval whereas digital ultrasonic sensors provide discrete pulse-width modulation (PWM) outputs when triggered. This makes them ideal for measuring distances precisely with no direct contact between transmitter/receiver units - great in robotics applications! Ultimately, your choice will depend on what type of input you need from your application: logic level values versus raw voltages – make sure you choose carefully depending on your needs!

6. How do I connect ultrasonic sensor to Raspberry Pi 4?

Connecting an ultrasonic sensor to a raspberry pi 4 4gb is fairly straightforward. The first step is to identify the pins on your specific device, and then connect each pin directly onto the corresponding GPIO port of your raspberry pi 4 4gb. Once these are secure you can install any necessary software packages such as Python before proceeding with programming the connection between your sensor and raspberry pi 4 4gb. After verifying correct communication just run through some basic tests ensuring that all data collected from various readings is being sent accurately back into the system for further analysis or decision making tasks either by yourself or other programs running alongside it in parallel operations . With simple applications like this you should be able to easily integrate numerous components into one physical platform allowing for much more sophisticated control projects while still remaining compact thanks largely due its small size coupled with greater processing power than what was previously available form earlier models like earlier generation Pis 3 B+.

Back to blog

Leave a comment

Please note, comments need to be approved before they are published.

You may also like to read