Communications: Radio Frequencies
Satellites use a small portion of the radio frequency band to receive signals and relay them back to Earth. Interference with a satellite’s radio signal can be caused by solar weather, other satellite signals, or terrestrial commercial technologies. Radio frequency interference (RFI) is characterized as any unwanted signal received by a device that prevents clear or best signal reception.
No nation owns the radio frequency spectrum, but all nations depend on keeping it free from interference. Space-based services can be particularly vulnerable to interference because satellites in space cannot easily increase their transmitted power when faced with increased noise. Many space services are not traditional two-way communications, but include passive monitoring (weather), active sensing (remote sensing) and/or one-way broadcasting (GPS). As a result, critical frequency bands require special international protection.
There is growing pressure on all frequencies from terrestrial commercial technologies, making regulatory protection more important than ever. International management of the use of the radio-frequency spectrum and satellite orbits is regulated by the International Telecommunication Union. In the U.S., the Federal Communications Commission, in partnership with the National Telecommunications and Information Agency, is entrusted with protecting the national security, public safety requirements and scientific federal agencies relying on space systems.