Automatic Direction
Finder
or
Automatic Direction Finding System
a navagation system used by aircraft and sea-going ships. It consists of one or more ground stations that transmit a signal in the
225 to 500 kHz (.225 to .500
MHz) range. Because of the low-frequnecy of these signals, their range is very good and not limited by the line-of-sight range of the
VOR system. The recevier in the airplane/boat uses a loop
antenna to "home-in" on the station. There is also a long-wire receiving antenna installed on many aircraft. Most ADF receivers can also recieve the AM broadcast band (
530 to 1710 kHz) so pilots can also
home in on powerful broadcast stations.
ADF signals should not be used in thunderstorms because the high amount of electro-magnetic interferance that
lightening causes.
Many pilots can't even use the ADF system, which is a shame, becuase of better systems such as VOR and the GPS systems.
"In most of the third world, the ADF
navigation system is the only
way to go"