What is radar and how does it work?

What is radar?

Radar is a sensor that is mainly used for three different things as they are; measure speed, detect and locate objects on the map. Its name is due to the acronym of the English words “radio detection and ranging” or in Spanish “radio distance detection and measurement”.

Radar

How does the radar work?

This device works primarily with a transmitter and a receiver. The first is responsible for generating radio waves of high intensity and frequency, when the signal finds an object it bounces generating an echo which returns to the same point where the signal was sent so that the receiver processes and interprets the generated data such as the time and the Doppler effect that is generated (the further the object is, the lower the frequency will be and the closer it is, proportionally the same).

Internal radar parts

The radar has several internal parts and each of them is essential for its operation.

 

Frequency generator 

It is responsible for generating the exact frequency with which the system will synchronize or work and determines when the transmitter works.

 

Transmitter and modulator

This generates a signal from and transmits it to the ground to be sensed. The signal it emits is high frequency so there is no interference with other signals.

The modulator is responsible for adjusting the signal either in amplitude, frequency or phase for the operation to be more suitable for measuring distance.

Transmitter and modulator

 

Duplexer

This is responsible for turning the transmitter and receiver on and off, according to the process in which the system is located.

Duplex

 

Receiver

It is responsible for receiving all the signals from the environment, filtering those outside the system and when it captures the indicated one it amplifies it for proper processing.

 

Signal and data processor

It processes the signal of the received echoes and converts the data obtained to be able to show on the display the distance and speed as the case may be.

Enrique ZL [ CC BY-SA 4.0 ], via Wikimedia Commons

Display 

It is the visual part of this system in which it tells us if there is any object in the radar measuring range.

radar display

 

 

Types of radars

Within the types of radars there are mainly two different classifications, pulsed wave, and continuous wave.

Pulsating

These are known by marine radars since they can commonly be found on merchant ships, this radar transmits a high-frequency signal in a pulsed way, after sending a pulse there is a waiting time to verify if an echo of the signal returns. These can detect the direction, distance, and speed of any object.

Within this category, we can find 3 different types according to the wave frequency

  • High PRF (greater than 30Khz),
  • medium (between 3 and 3 Khz)
  •  low (equal to or less than 3Khz).

 

Continuous-wave

These radars transmit the signal continuously, they base their operation on the Doppler effect and we can find different classifications.

 

Number of antennas

  • Bistatic: it  has two antennas, one for broadcast and one for reception
  • Monostatic: It  only has one antenna for emission and reception
  • Quasi-monostatic:  The antennas are together with the naked eye it seems that it only had one antenna but it has two.
  • Multistatic:  It has several antennas and processes the information of each one.

 

Waveform

  • Unmodulated:  It is based on the Doppler effect and is only able to calculate the speed of the object.
  • Modulated:  The system transmits a signal within a range of frequencies recognized by the system.

By objective identification 

  • Primary radar: This is responsible for detecting the target:
  • Secondary:  It is mainly used for aircraft identification.

For its purpose

  • Tracking:  Created for automatic object tracking.
  • Search:  Used to detect targets in areas of interest.