English: Collision Warning with Brake Support (Photo credit: Wikipedia)
July 3, 2012, the FCC has amended Part 15 rules to enable enhanced vehicular radar technologies in the 76-77 GHz band, and to allow fixed radar applications at airports with an aim to improve safety for personnel and equipment.
The amendment includes a relaxation of limits for vehicular radar technologies, and is justified within the Report and Order, citing that maximum permissible limits for human exposure to RF electromagnetic fields had not been established at the time the rules were originally adopted (1995), and the original limits, intended to protect pedestrians in the proximity of stopped vehicles, are far more restrictive than the currently adopted RF exposure levels.
The modifications are applicable specifically to sections 15.35 and 15.253 of title 47 Part 15.
The amendment to section 15.35 eliminates the requirement that vehicular radars decrease power when the vehicle is not in motion. Furthermore this modification specifies a new relaxed emission limit for 76-77 GHz front, side, and rear illuminating vehicular radars. The FCC takes these actions in response to petitions filed by Toyota Motor Corporation (TMC) and Era Systems Corporation (Era).
The modification of section 15.253 will allow fixed radar systems operating in the 76-77 GHz band to be installed at airport locations. These systems are used for foreign object debris (FOD) detection on runways as well as the ability to monitor aircraft and service vehicle traffic on the taxiways and other non-public ground locations.
The FCC justifies these modifications within the Report and Order claiming they “will provide more efficient use of the spectrum, and enable the automotive and aviation industries to develop enhanced safety measures for drivers and the general public”.
The 76-77 GHz band is considered Extremely High Frequency (EHF), and is within the “W band”, 75 GHz to 119 GHz. The EHF spectrum is what is commonly referred to as the millimeter wave spectrum, which is considered to begin at 30 GHz and end at 300 GHz.
The 76-77 GHz band is primarily allocated to the Radio Astronomy Service (RAS) and the Radiolocation service. Amateur and Space research (space-to-Earth) services utilize this band on a secondary basis.
The National Radio Astronomy Observatory (NRAO) and National Academy of Sciences’ Committee on Radio Frequencies (CORF) has raised concerns about increased interference potential to radio astronomy operations if the rules are adopted. NRAO argues that vehicular radars may interfere with radio astronomy receivers over distances up to approximately 60 miles. NRAO states that “destruction of radio astronomy receivers is a serious possibility” due to the high powered vehicular radars. The Automotive industry disagrees with the claims citing that they are speculative. The FCC notes that vehicular radar has been permitted in the 76-77 GHz band since 1995, and that an increase in potential interference as a result of the rule change is negligible.