From SKYbrary Wiki
Non-Directional Beacon is defined as a radio beacon operating in the MF or LF band-widths.
A non-directional beacon (NDB) is a radio beacon operating in the MF or LF band-widths. NDBs transmit a signal of equal strength in all directions. The signal contains a coded element which is used for station identification (normally 1-3 letters in Morse Code).
NDBs are often associated with Non-Precision Approach procedures.
Automatic Direction Finding (ADF) (ADF) equipment on board aircraft uses bearings from NDBs for navigation purposes.
- Automatic Direction Finding (ADF);
- VHF Omnidirectional Radio Range (VOR);
- Distance Measuring Equipment (DME);
- Instrument Landing System (ILS);
- Global Positioning System (GPS);