20 Applications of Doppler Effect

20 Applications of Doppler Effect

Whether it’s figuring out the idea behind the variations in siren pitches of an approaching and receding car or the concept behind the use of a speed gun by traffic officers, we encounter the Doppler effect daily, knowingly or unknowingly. And its application across various industries is inexhaustible.


Doppler effect is a unique concept that involves analyzing the change in wavelength and frequency of wave energy (sound, radio, lightwave) transmitted from a source and reaching the onlooker relative to the change in positions of either the wave source and/or the observer. That said, the compression and spreading out of sound waves when a siren-sounding car approaches and recedes is what leads to the variations in siren pitch.

This article is going to explore some of the real-world applications of the Doppler effect across various industries.

Applications of Doppler effect

1. Observation of distant stars in astronomy

Doppler effect has been a powerful tool in astronomy when it comes to detecting and observing stars in space. Stars consistently transmit light energy towards the surface of the earth that can be seen. The closer a star approaches us, the more its light wavelengths are squashed, and the colour of light it’s emitting tends to blue (blueshift). In contrast, the farther away it moves from us, the more its light wavelengths spread out, and its colour tends to red (redshift).

2. Detection and location of exoplanets

Just like in the observation of stars by astronomers, the Doppler effect has been found useful in the discovery of exoplanets. Because of the small size of exoplanets, identifying and locating them in outer space is usually a challenge due to occlusion by other parent planets. The use of the Doppler effect is so suited to solving such challenges that even the atmospheric conditions of the body can be determined.

3. Application in pulse-Doppler RADAR

A pulse-Doppler RADAR is a special instrument that’s installed in aircraft to help detect types of precipitation in the atmosphere as well as the intensity in order to help pilots easily navigate around such obstacles. It uses the Doppler effect to determine the precipitation’s velocity and location.

4. Application in RADAR speed guns.

A RADAR speed gun is a unique tool used mostly by traffic personnel in speed limit enforcement to determine the speeds of moving vehicles. A speed gun uses the Doppler effect to determine how fast a returning radio wave has been altered by an object’s motion in order to figure out the distance and velocity of the object.

5.Application in laser Doppler anemometers.

An anemometer is an instrument that is used to figure out wind velocity. A laser Doppler anemometer is a special type that is fitted with both transmission and receiving devices. The devices are crucial in the utilization of the Doppler effect to calculate air velocity.

6.Application in echocardiograms

An echocardiogram is a device used to assess the functioning of the heart. A special type though is a Doppler echocardiogram that uses the Doppler effect to assess the structure of the heart as well as its movements. It usually emits sound pulses towards the heart that when they bounce off of the heart, they return back to collect the desired information.

7. Application in flow and level sensors

Doppler effect has found its application in fluid dynamics where it has been deployed in the process of determining a fluid’s velocity. Because of the non-intrusive nature of flow and level sensors, this technique can be useful in cases where a liquid or gaseous flowing substance is highly reactive.

8. Application in some speakers

Leslie speakers’ operational performance is largely dependent on the Doppler effect. A Leslie speaker uses an electric motor and an amplifier where the sound wave signals emitted are utilized by the Doppler effect to amplify the sound produced.

9. Application in professional sports

Doppler effect has been widely utilized in professional sports like cricket, athletics, tennis, et cetera. A speed gun is mostly used in cricket to calculate bowling speeds. In tennis, the number and speed of serves can be determined by a speed gun also, whose operation is based on the Doppler effect.

10. Application in robotics

Doppler effect is crucial in helping robotics map out their environment for easier navigation especially in sophisticated surroundings with objects in constant motion. In the robotic field, LIDAR is usually integrated with RADAR that uses the Doppler effect to produce a more robust and reliable autonomous system.

11. Detonation of explosives

The entire process of detonation of explosives in the military is largely dependent on the Doppler effect. This exercise is usually aided by the proximity fuze.

12. Application in obstetric ultrasonography

Doppler effect has a myriad of applications in the medical field. In order to monitor fetal heartbeat and its movement pattern in the womb, a procedure known as obstetric ultrasonography that uses the Doppler effect of sound waves is performed.

13. Application in neurology

Because of the Doppler effect’s ability to be used in the measurement of the speed of blood flow, its application in neurology is key in the detection of vascular disorders.

14. Measurement of the blood velocity profile

An Ultrasonic Doppler Velocimetry (UDV) is a medical device that uses the Doppler effect to determine the velocity of blood flow as well as construct its profile. Moreover, this procedure is entirely non-invasive thus it’s well suited for fluids that contain floating or pulsating particles.

15. Application in satellites

Satellite navigation is another impressive application of the Doppler effect. Non-interrupted communication is key between satellites, and this is where the Doppler effect comes in.

16. Measurement of vibrations

Doppler effect has also been exploited in the determination of vibration frequency and intensity in target objects across many fields. This technique uses a laser Doppler vibrometer.

17. Application in embryonic biology

Furthermore, the Doppler effect has been useful in the cleavage phase of embryos.

18. Application in marine

In order to accurately figure out the speed of an automobile in marine, the Doppler effect comes into play where the variation in radio wave signals emitted by a transmitter facilitates the process.

19. Application in aeronautical environment

Doppler effect can also be used in the estimation of aircraft speed as well as drone velocity for appropriate action.

20.  Measurement of lightning intensities

Lastly, the application of the Doppler effect in aeronautical navigation cannot be overemphasized. In order to safely navigate in space, a lightning detector is usually installed on an aircraft to track the intensity and direction of lightning strikes. The radio waves transmitted by these detectors exploit the Doppler effect principle to collect the desired data.

The bottom line

In conclusion, the Doppler effect is a phenomenon where the relative shift in a wave’s frequency and wavelength is determined by the change in position of the wave source and the target object. A classic example is the variations in siren pitches as a result of distance changes between the car and observer.

The applications of the Doppler effect ranges from observation of distant stars, location of exoplanets, medical ultrasonography, RADAR speed guns in speed limit enforcement to professional sports like crickets and tennis, to mention a few.

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