Distance Sensors - RADAR

Basic Description

Some cars and trucks are equipped with headway sensors that detect the distance between a vehicle and any vehicles or large objects in front of the vehicle. These sensors are used by adaptive cruise control and/or collision avoidance systems. Most existing headway sensors use a 76.5 GHz radar, but other frequencies (e.g. 24 GHz, 35 GHz and 79 GHz) are also in use. Some systems use infra-red sensors instead of (or in addition to) the RADAR sensors.

RADAR sensors work by transmitting a burst of electromagnetic energy at a particular frequency and "listening" for the reflected signal. The delay associated with reception of the reflected signal can be correlated to the distance of the reflecting object. Radar signals are very good at detecting objects that strongly reflect electromagnetic radiation (e.g. metal objects). Because they operate at wavelengths on the order of a few millimeters, automotive radar systems are pretty good at detecting objects that are several centimeters or larger. They are also good at looking through (i.e. ignoring objects that are small relative to a wavelength (e.g. the water droplets in fog).

Possible automotive applications of radar sensors.

Other automotive systems that use radar distance sensors include collision avoidance systems, blind spot detection systems and automated parking systems.

Manufacturers

Bosch, Infineon, Smartmicro

For More Information

[1] Volvo's Adaptive Cruise Control , YouTube, April 2007.

[2] VW Passat CC Park Assist Vision , YouTube, April 2008.

[3] Seeing Past the Blind Spot , YouTube, March 2008.

[4] Infineon SiGe IC used in Bosch Automotive Radar System, Semiconductor Today, Dec. 2, 2008.