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Radar Sensors

University of Washington_021124A
[University of Washington]

- Overview

Radar sensors (Radio Detection And Ranging) are active devices that emit microwave signals and interpret the reflected echoes to detect, track, and measure the distance/speed of objects, working reliably in harsh conditions like rain, dust, or extreme temperatures where optical sensors fail. 

They use the Doppler effect for motion sensing and find uses in automotive safety (collision avoidance), industrial automation (level sensing, vehicle positioning), and even drones, by sending out radio waves that bounce off objects and return with data about their presence, position, and velocity.

1. How Radar Sensors Work:

  • Transmission: An antenna sends out low-energy electromagnetic waves (microwaves).
  • Reflection: These waves travel until they hit an object, at which point they reflect back towards the sensor, like an echo.
  • Reception & Processing: The sensor's antenna receives the reflected signal. By measuring the time it takes for the signal to return (Time-of-Flight) and analyzing frequency shifts (Doppler effect), the sensor calculates the object's distance, speed, and direction.


2. Key Characteristics & Advantages:

  • Weatherproof: Unaffected by rain, fog, dust, or extreme temperatures.
  • Contactless: Detects objects without physical contact, ideal for harsh environments.
  • Motion Detection: Excellent for identifying moving objects and their speed.
  • Versatile: Can measure distance, level, presence, and velocity.


3. Common Applications:

  • Automotive: Adaptive Cruise Control (ACC), Automatic Emergency Braking (AEB), blind spot detection, parking assistance.
  • Industrial Automation: Level measurement in tanks, vehicle positioning in car washes, robotic guidance.
  • Building Automation: Occupancy detection, people counting, fall detection.



4. Types of Radar Sensors:

  • Pulsed Radar: Emits short pulses and measures the time for the echo to return.
  • FMCW (Frequency Modulated Continuous Wave): Transmits continuous waves that change frequency, providing more precise distance and velocity data.
  • mmWave (Millimeter Wave): Uses very high frequencies for high-resolution imaging, common in modern cars.

 
 

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