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The dipole antenna of a radar altimeter of 1947. A radar altimeter (RA), also called a radio altimeter (RALT), electronic altimeter, reflection altimeter, or low-range radio altimeter (LRRA), measures altitude above the terrain presently beneath an aircraft or spacecraft by timing how long it takes a beam of radio waves to travel to ground, reflect, and return to the craft.
The United States FAA has warned that radar altimeters on aircraft, which operate between 4.2 and 4.4 GHz, might be affected by 5G operations between 3.7 and 3.98 GHz. This is particularly an issue with older altimeters using RF filters [ 164 ] which lack protection from neighboring bands. [ 165 ]
Frequency bands for 5G New Radio (5G NR), which is the air interface or radio access technology of the 5G mobile networks, are separated into two different frequency ranges. First there is Frequency Range 1 (FR1), [ 1 ] which includes sub-7 GHz frequency bands, some of which are traditionally used by previous standards, but has been extended to ...
Concerns that 5G service could interfere with airplane altimeters, which give data on a plane's height above the ground and are crucial for bad-weather landing, led to brief disruptions at some U ...
Radar echoes, showing a representation of the carrier. Pulse width also determines the radar's dead zone at close ranges. While the radar transmitter is active, the receiver input is blanked to avoid the amplifiers being swamped (saturated) or, (more likely), damaged.
Pages in category "Earth satellite radar altimeters" The following 19 pages are in this category, out of 19 total. This list may not reflect recent changes. C.
Radar altimeter technology is also used in terrain-following radar allowing combat aircraft to fly at very low height above the terrain. After extensive research and experimentation, it has been shown that "phase radio-altimeters" are most suitable for ground effect vehicles, as compared to laser, isotropic or ultrasonic altimeters. [3]
In December 2021, Boeing and Airbus called on the US government to delay the rollout of new 5G phone service that uses C band due to concern of the interference with some sensitive aircraft instruments, especially radio altimeters operating at 4.2–4.4 GHz. [17]