Radio waves are used for different purposes other than transmitting audio, video and for communication. One of their primary uses includes detecting the presence of objects in the atmosphere, including aircraft, clouds, and precipitation. This is done mainly through Radio Detection and Ranging or RADAR. By noting the time of flight that a single pulse takes to return after reflection from an atmospheric object, it is possible to estimate the distance of the object.
To detect a target, radar systems generate an electromagnetic pulse, focus it, and transmit it using an antenna. Objects in the path of the transmitted pulse scatter most of its energy. However, some of this scattered energy returns to the radar system and is gathered by the same antenna, which then feeds it into a receiver.
The receiver determines the time taken for the pulse to make a round trip from the radar to the target and back. As the electromagnetic pulse travels at the speed of light, its multiplication with the time of travel gives the total distance travelled by the pulse. Therefore, the actual distance to the target is half this total distance.
Manufacturers feel radar is a versatile gadget for use in automobiles. For instance, it can help the driver estimate the distance between his/her vehicle and other objects in front, sides, or back – promoting safer driving. Following this lead, manufacturers have been shrinking the size of the radar system to make it suitable for use in automobiles.
At present, the smallest radar is the 77GHz radar transceiver from NXP Semiconductors N.V. It is a single chip device, roughly the size of a postage stamp. Consequently, manufacturers can place the chip anywhere in the vehicle. This is a very big advantage to vehicle designers, as they are targeting driverless, fully automated driving in the near future, and need increasing numbers of sensors within the vehicle. In fact, Google engineers are already field testing working prototypes of the NXP device for their self-driving cars project.
The reference design from NXP is a 35×35 mm printed circuit board and it has a radar front-end, two MCUs for signal processing, and supporting components. Designers can use this in their self-driving cars, in the form of a cocoon comprising 10-20 tiny radar sensors all around the vehicle to provide a high-resolution, 360-degree view of the environment around it.
ADAS or Advanced Driver Assistance Systems also use radar as their core technology, using it to make driving easier and safer. For instance, they use it for adaptive cruise control, lane change assist warnings, forward collision warnings, blind spot monitoring, emergency braking, and automated braking. According to IHS Research, the market for radar-based ADAS will grow by 23 percent year-on-year, increasing from the current year to more than 50 million radar sensors.
Although alternate technologies presently exist for avoiding collisions, mostly in the form of laser-light and ultrasonics based systems, the 77GHz radar offers a superior performance under adverse conditions such as road grime, fog, and rain. So far, bulky hardware had made it difficult to use radars in vehicles, but not anymore.
