Short Range Radar (SRR)

Automotive Short-Range Radar (SRR) are radar systems operating around a car when in motion to detect possible impacts with obstacles, such as other cars, walls, pedestrians, etc. so that safety measures may be triggered automatically, such as pre-tensioning of seat belts and inflating airbags. Ultimately, this could include automated braking to avoid or to mitigate collisions.

The SRR systems consists of a number of radars that can be used for a number of different functions, including:

• Parking assistance: Rear-mounted sensors, with a range of 1.8-meters, can detect small objects in front of large objects and measure direction of arrival
• Pre-crash sensing: The sensors scan out up to 30 meters to provide an advanced warning of an imminent collision to arm airbag, pre-tension seat restraints or other injury mitigation strategies
• Blind spot detection: Short-range sensors detect objects in critical zones
• Obstacle detection: With up to a 30 meter operating range, the radar sensor can be used to warn of unseen objects

Short Range Radar

Automotive short-range radars are permitted to use two harmonised frequency bands in the European Union: 24 GHz and 79 GHz. Since technology for the latter is not considered mature for commercial implementation as yet, the 24 GHz band may be used until 30^th June 2013 with some detailed regulatory measures to avoid interference with existing users in the 24 GHz range, such as radio astronomy stations.

The 24 GHz band is actually a band of 5 MHz around 24,15 GHz (24,15 +/– 2,50 GHz; 21,65 to 26,65 GHz). The maximum mean power density is –41,3 dBm/MHz (eirp) and the maximum peak power density is 0 dBm/50MHz eirp, except for frequencies below 22 GHz, where the maximum mean power density shall be limited to -61,3 dBm/MHz eirp.

The 79 GHz band is 4 GHz width (77 - 81 GHz). The maximum mean power density is -3 dBm/MHz (eirp).