What is Doppler Radar? A Detailed Guide


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Doppler radar is one of the more unique radar technologies due to its sheer number of uses. 

This page will tell you how Doppler radar works, the use of the radar and radio waves, and how it is different from traditional radar options.

A Definition of Doppler Radar

Doppler uses a scientific principle known as the Doppler effect (more on that in a short while)

The idea is that a Doppler method fires out radio waves, very similar to what a standard radar would do. These called radio waves then hit an object and bounce back to the Doppler receiver.

The radar receiver will look at the signals that are returned (known as the echo signals) and determine:

  • The location of an object
  • The speed and velocity at which an object is traveling. 
Dual Polarization Moving Away From Radar
Dual Polarization Moving Away From Radar
Dual Polarization Receive Signal
Dual Polarization Vertical Signal

Explaining The Doppler Shift

The Doppler Shift is a complicated scientific principle. So, let us give you the basics. 

The shift is something you have likely already experienced, even if you didn’t know that you were experiencing it.

Think about how a person’s voice changes as they get closer to you. Their pitch changes. How loud they are changes. The same with a car. How a car sound is different. When it is coming toward you. Then, when it is going away.

This is all down to how the sound waves are moving. The ‘shift’ is based on the positioning of an object emitting the sound and where it is moving.

As an object moves closer, the ‘pitch’ gets higher as the soundwaves are closer together. The pitch gets lower as the soundwaves become more spread out as it moves away.

Yes. We know it can be not very clear. However, luckily, you don’t have to understand the Doppler Shift much beyond the following points:

  • An object further away has less frequent soundwaves, which creates a low pitch.
  • An object closer has more frequent soundwaves, which creates a high pitch.
  • It functions by transmitting a beam of electromagnetic radiation waves from the transmitter (TX Antenna)

How Is Doppler Radar Used?

What is Doppler Radar?
What is Doppler Radar?

Doppler is an incredibly versatile piece of tech, and as a result, it is used in several different ways.

For example, many law enforcement forces use Doppler for their speed detectors. This is because you can’t get much more accurate than Doppler. 

What is Doppler Radar and How is it Used?

What is Doppler Radar and How is it Used?
What is Doppler Radar and How is it Used?

You will also find it heavily used in the weather predicting industry. This is because the radar can be used to determine how certain types of weather are moving (based upon the frequency that they bounce back)

Many aircraft, particularly commercial aircraft, are kitted out with Doppler as it is used for navigation. It enables the plane to specify the speed it is traveling, nearby aircraft, obstacles, etc. 

It also has substantial military applications. Doppler has been in use by the military since WWII. It can aid in spotting enemy forces, determining the direction they are traveling, etc.

How Does a Doppler Radar Work?

The concept behind a Doppler is relatively simple. A transmitter pumps out a set frequency radio pulse.

The radio wave will then keep moving forward until it hits an object. When the radio pulse hits an object, it will bounce back due to the shift mentioned earlier. 

If the object is moving, the frequency of the radiowaves will have changed. 

Sound waves are lengthened as an object drives away from a spot, resulting in a lower frequency.

The radar receiver will analyze the frequency that bounced back to determine the direction an object is moving and its speed. 

Doppler Radars vs. Conventional Radars

Traditional radar systems look at how long it takes for a radio wave to bounce back. This determines the speed at which an object moves (or how far away it is). The problem is that traditional radar systems tend to be relatively weak, and they aren’t brilliant at looking over large distances unless you have a massive radar set up.

How is Doppler Radar Different From Regular Radar?

Doppler radars look at the change in frequencies when the radio wave bounces back. Doppler radars are also quite powerful, even if the radar is in a small package. You will also be able to hear the radio waves emitted from radar, but you can’t with a conventional tracking system setup.

Due to how radars work, they are impossible to jam or fool. You can easily use a radar jammer on a conventional design, which is why many places avoid using them.

Finally, Doppler scanning systems are more accurate at tracking objects moving away from the radar. It can rule out false positives (it will ignore any radio wave that bounces back at the same frequency), and the wave can be much more targeted.

What is the Advantage of Doppler Scanning Systems?

The significant advantage of radar is an incredibly versatile piece of technology. In fact, it is the most versatile of scanning system technologies.

As we mentioned previously, it has a range of uses. People can use it for weather forecasting and severe storms. 

It can also detect the following kinds of precipitation hail, snow and wildfire smoke, and airborne tornado debris.

From a volume scan (a series of 360-degree sweeps), forecasters can get a precise look at configurations and motions in windstorms relative to the radar.

It is used to scan a moving object by a police officer to detect speed. It even has military applications to enable troops to see combat movement, even in the dead of night.

Doppler is also an incredibly lightweight piece of technology. It is incredibly portable, and it often requires less equipment than other devices.

Of course, it is also incredibly accurate. Doppler is probably the most accurate tech that we have at the moment. 

Conclusion

Doppler radar is an incredibly sophisticated piece of technology. It relies on the principle ‘The Doppler Effect. Due to their sheer accuracy and potential uses, many top radars are constructed using Doppler principles. 

References

https://www.fierceelectronics.com/sensors/what-a-radar-sensor#:~:text=One%20of%20the%20biggest%20advantages,speed%20along%20with%20its%20direction.

https://www.quora.com/How-is-Doppler-radar-different-from-regular-radar

https://www.weather.gov/jetstream/how

https://www.physicsclassroom.com/class/waves/Lesson-3/The-Doppler-Effect

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