Doppler Effect: How Doppler Radar Works

Curious to know more about the phenomena called Doppler effect and how it helps us in many ways possible, here is some information on Doppler effect and Doppler Radars…

What is Doppler effect?
The Doppler effect was named after the scientist who perceived it, this is the famous Christian Doppler who is now popular thanks to the ever-useful Doppler Radars. But before we discuss Doppler Radars, lets talk about the Doppler effect.

The Doppler effect is the effect that is produced by a moving source of waves in which there is an obvious shift upward in the frequency for people or observers towards whom the source is approaching and an obvious shift downwards in the frequency for people from whom the source is moving away. You need to know that this shift in effect doesn’t occur because of the real change in frequency of the source. The effect only changes because of the change in distance. The Doppler effect can be observed in any type of wave whether water wave, sound wave or light wave.

Lets simplify the Doppler effect for you. Think of an ambulance or a fire engine truck on a highway with its siren blaring. While the vehicle was traveling towards you, you could hear the high pitch of the siren, but suddenly after you pass it by the pitch lowers and drops. This is the perfect example of the Doppler effect. The very obvious shift in frequency of a sound wave produced by a source on the move.

How Doppler radar works?
Radar is a device that is used in every aspect of life, though in most cases it will be invisible to us. The Air Traffic control uses radars to trace places on ground and in the air. It is also used to guide planes for smooth and safe landings. The Police force also uses radars to gauge the speed of motorists. The Military uses radars for enemy and weapon detection. And lets not forget NASA who uses radars to map the planets and track satellites in the universe.

Radars are most commonly used in detecting and predicting weather conditions. What information we hear on the use has an actual scientific process behind it. Most weather radars use the Doppler effect while there are still a few using microwave signals. Doppler radars are much more accurate than the older style radars. In Doppler radars the signal is sent out a constant rate. This signal is then shifted according to the Doppler effect as it returns. The amount of the signal shift depends up on the speed of the target. This signal is picked up and interpreted with greater accuracy that other radars.

Doppler radars are considered to be the best tool for detection of rainfall in an area. The way they work is by sending out beams in a circular pattern around the radar. When any of these beams strikes a raindrop, part of this particular beam will be reflected back to the radar. The radar then receives the reflected beam and calculates the distance away and its intensity and from the direction it is moving and the wind velocity. The radar then translates the distance and intensity on to a graphical map that is displayed on TV (the kind you see on TV).

The use of Doppler radar applications and live Doppler radars is possible in every possible activity in life, but in most cases we wont even be aware of the close contact we have with Doppler radars or Doppler effect.