Radio astronomy and aeronautical telemetry don’t mix

Competition for limited spectrum pits radio astronomers against the FAA and airline industry.

Is probing the origins of the universe a better use of spectrum than testing new aircraft? That is one of the big questions that the World Radiocommunication Conference  will answer this fall in Geneva. Defense Department and aircraft manufacturers, such as Airbus and Boeing, will be vying for a slice of spectrum that scientists use for radio astronomy at installations such as the very large array (VLA), which the National Radio Astronomy Observatory (NRAO) operates at a remote site in southwest New Mexico.The International Telecommunications Union has identified a range of bands that are necessary for aeronautical telemetry, which supports flight test operations. The bands the union selected include the 4400 MHz to 4940 MHz band that the radio astronomers use.Radio telescopes, such as the 27-dish VLA in New Mexico, scan the universe by tuning in to radio waves emitted from stars, galaxies and other celestial objects. Those signals have a low noise threshold and low tolerance for interference, NRAO told the Federal Communications Commission. NRAO said it opposed any decision to let industry or the government use the 4400 MHz to 4940 MHz band for aeronautical telemetry.Radio astronomy systems and aeronautical telemetry operating within line of sight of each other would be grossly incompatible, NRAO said, adding that radio astronomy could not tolerate any incursions into the 4400 MHz to 4940 MHz bands.