Radar is an acronym for Radio Detection and Ranging, and it’s a rather common method for detecting objects in motion.
Radar is an acronym for Radio Detection and Ranging, and it’s a rather common method for detecting objects in motion.
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Driving technology Applications for radar in vehicles

Author / Editor: Jason Unrau / Nicole Kareta

Advanced driver-assist systems are among the most advanced technologies in mass-market cars today. Functions like adaptive cruise control and collision avoidance systems improve driver safety and convenience, and much of it uses radar. Here are practical applications for radar in vehicles.

Radar was initially made popular in weather and military applications to show aircraft or precipitation within a defined range. The same technology has become a cornerstone of many automotive functions as a convenience or safety-based system. For collision avoidance, pedestrian detection, and ADAS and autonomous driving systems, radar is perhaps the most cost-effective and reliable technology that can be used. How is it different than other radar systems? What is it used for specifically, and how does it work?

How automotive radar differs

Radar is an acronym for Radio Detection and Ranging, and it’s a rather common method for detecting objects in motion. As used in traffic enforcement, Doppler radar transmits pulses of radio waves to measure the change in phase between the pulse and the echo, effectively measuring velocity. The same is used in weather services. Radar in automotive uses much the same technology. The difference is primarily in the wavelength used. For weather radar, a wavelength of 8 to 15 centimeters is commonly used due to the long distances they travel. For traffic police, radar devices use a wavelength of 9mm to 1.2cm, typically.

Automotive radar systems operate on much smaller wavelengths, and in two classifications. Short-range radar systems (SRR) are just a millimeter or two and long-range radar systems (LRR) have a wavelength of 3.9mm. SRR systems are for close-proximity technologies – those that operate within 30 meters while LRR extends out to 150m. To prevent interference, each type of radar frequency is allocated a bandwidth of its own.

Applications for radar in automotive

With reliability and ultra-fast responses being the drivers behind using radar, there have been many applications developed that use LRR or SRR radar in automotive.

Adaptive cruise control

Operating on LRR wavelengths, adaptive cruise control is one of the most convenient features from the past decade. It allows the driver to set a desired maximum speed without needing to adjust the set speed when traffic moves slower than the max. LRR radar sends out short wavelength beams that reflect off vehicles travelling ahead. If the system senses that the car is decelerating and getting within the set follow distance, it reduces the vehicle’s speed automatically to maintain a safe distance.

Collision avoidance

On the SRR spectrum, collision avoidance sends a tight radar signal ahead to detect unexpected obstacles within a concerning range. That range varies depending on vehicle speed. When the radar senses an obstacle at a range that will present a danger if no action is taken, a warning is projected for the driver. Automatic emergency braking works in conjunction with collision avoidance technologies as well. For vehicles so equipped, the brakes can be autonomously applied to avoid a collision or mitigate the damage experienced. In some cars, autonomous steering input is also engaged.

Pedestrian detection

Also in the SRR range, pedestrian detection operates at slow speeds. Just like collision avoidance, the radar indicates when an object or person is in the vehicle’s path and alerts the driver. The same technology is used for parking aids.

Is radar still applicable?

Other technologies have emerged that perform the same functions as radar. LiDAR, for example, uses light instead of sound waves to detect objects. Lasers have also been used in some applications. At the moment, radar continues to be reliable and efficient, plus the most cost-effective option for most applications. That may change as other technologies emerge or refine, but don’t expect radar to be eliminated from the industry anytime soon.