Introduction
Radar systems are electronic systems that use radio waves to detect objects in the surrounding environment. The system transmits radio waves outward into the air, where they can bounce off of objects in the radar's transmission path. The waves that bounce and return to the radar, called pulses, are then received and analyzed by the radar system, which can then determine the shape, position, and velocity of the discovered objects relative to the radar.
How Radars Work
All radars work using the same basic components:
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Below is an example of a simple radar system:
Types of Radar Systems
Doppler Radar
The Doppler Effect
Most small-scale radar systems are considered Doppler radars. A Doppler radar uses the Doppler effect to calculate the velocity of moving objects relative to the radar. The Doppler effect describes how the observed frequency of a wave emitted from a moving object changes based on the relative velocity to the observer. The observed frequency will be higher if the object emitting the wave is moving towards the observer and lower if moving away from the observer. Using this principle, a Doppler radar can calculate the position and velocity of the moving object.
The specifications of Doppler radars vary by part, but in general they work as long-range, low-resolution sensors for measuring distance and velocity of obstacles.
Using Radar Sensors
Advantages
- Long range: Many radar sensors will have a range that easily surpasses 100m
- Reliable: Radar is not significantly affected by lighting, weather, or dust, and is suitable for nearly all outdoor conditions
- Relatively low power consumption
Disadvantages
Low field of view: FOV is especially low at long range, often falling below 20°. For a complete view of the surroundings, the sensor will need to be rotated in the direction that needs to be observed
- Low resolution & accuracy: Radar sensors are not good for getting precise readings of the position and velocity of obstacles. They are more so for getting a general sense of where obstacles are so they can be avoided