7 📡 Radio Navigation
Relative bearing to station (ADF, VOR), radial from station (VOR), distance from station (DME), actual position (GPS, RNAV, INS).
7.1 VOR
very high frequency omnidirectional range
VHF, 108 - 117.975 MHz (just below aviation voice channels)
VHF carrier wave modulated by two LF signals, using phase difference comparison between them to signifz aircraft direction from transmitting station as one of 360 radials from it