Editing Radio navigation (section)

===VOR===
[[File:VOR DME BUB.JPG|right|thumb|VOR transmitter station]]
{{Main|VHF omnidirectional range}}
{{more citations needed|section|date=February 2022}}
[[VHF omnidirectional range]], or VOR, is an implementation of the reverse-RDF system, but one that is more accurate and able to be completely automated.{{fact|date=July 2022}}

The VOR station transmits two audio signals on a VHF carrier – one is [[Morse code]] at 1020&nbsp;Hz to identify the station, the other is a continuous 9960&nbsp;Hz audio modulated at 30&nbsp;Hz, with the 0-degree referenced to magnetic north. This signal is rotated mechanically or electrically at 30&nbsp;Hz, which appears as a 30&nbsp;Hz AM signal added to the previous two signals, the phasing of which is dependent on the position of the aircraft relative to the VOR station.{{fact|date=July 2022}}

The VOR signal is a single RF carrier that is demodulated into a composite audio signal composed of a 9960&nbsp;Hz reference signal frequency modulated at 30&nbsp;Hz, a 30&nbsp;Hz AM reference signal, and a 1020&nbsp;Hz 'marker' signal for station identification. Conversion from this audio signal into a usable navigation aid is done by a navigation converter, which takes the reference signal and compares the phasing with the variable signal. The phase difference in degrees is provided to navigational displays. Station identification is by listening to the audio directly, as the 9960&nbsp;Hz and 30&nbsp;Hz signals are filtered out of the aircraft internal communication system, leaving only the 1020&nbsp;Hz Morse-code station identification.{{fact|date=July 2022}}

The system may be used with a compatible glideslope and marker beacon receiver, making the aircraft ILS-capable (Instrument Landing System)}. Once the aircraft's approach is accurate (the aircraft is in the "right place"), the VOR receiver will be used on a different frequency to determine if the aircraft is pointed in the "right direction." Some  aircraft will usually employ two VOR receiver systems, one in VOR-only mode to determine "right place" and another in ILS mode in conjunction with a glideslope receiver to determine "right direction." }The combination of both allows for a precision approach in foul weather.<ref>[https://cdn.rohde-schwarz.com/pws/dl_downloads/dl_application/application_notes/1gpan09/1GPAN09_0E.pdf VOR/ILS Testing with Signal Generator SMT]</ref>