ALTIMETERS

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Context

The US Federal Aviation Administration (FAA) has warned that the new 5G technology could interfere with instruments such as altimeters.

About

An altimeter or an altitude meter is an instrument used to measure the altitude of an object above a fixed level.
So, in aviation it measures how far above the ground an airplane is travelling.
In addition to altitude, altimeter readouts are also used to facilitate automated landings and to help detect dangerous currents called wind shear.
Concern: Altimeters operate in the 4.2-4.4 GHz range and the concern is that the auctioned frequencies sit too close to this range.