Please Help - What are NDBs and ADFs

[GROUND AFFECT]

Hey all,

I am an avation enthusiast and I'm 15. I know what VORs are and how the work, but what about ADF's and NDB's? What do they do and how do they work?

Any help would be much appreciated.

Fly High,

GROUND AFFECT

[GROUND AFFECT]

Hey 2 of you have viewed this message in the last 10 minutes. Why no reply?

Come on, be kind.

[GROUND AFFECT]

6 of you have viewed but still no reply.

Please. I want to know so I can test out using them in FS200

[Evo7]

NDB - Non-directional beacon. This is a ground-based transmitter like a VOR, but just transmits in all directions. It's either a radio mast or a 'T' arial slung between two masts. It also transmits a morse Identifier, so you know you've got the right one :)

ADF - Automatic direction finder. Fitted in the aeroplane, and has a needle that indicates the direction from which the signals of a selected NDB are being received. Also known as a Relative Bearing Indicator (RBI). A more sophisticated version is the Radio Magnetic Indicator (RMI).

The ADF/NDB combination is, I think, the simplest radio nav. combination.

To use them in flight, you just tune the ADF to a given NDB frequency. They're used in conjunction with the heading indicator to track to or from an NDB and to fix the aircraft's position.

[Evo7]

Hey, I had to type it all in!! :rolleyes: :D

[Mark 1]

Oh alright then, here gos.

An ADF is an aerial direction finder - you tune to a radio station in the MF or HF frequency bands nad the needle on the indicator will point out the relative bearing of the radio station from the aircraft.

An NDB is an aeronautical radio beacon designed for reception and navigation with an ADF. These are usually homing beacons at airfields or on the approach path.

[GROUND AFFECT]

Hey thanks to both of you,

I'm sure I will have a beetr time flying using thenn ADF.

:) :D :rolleyes: :eek:

[Noggin]

NDBs were used in the Maritime Service long before the Aeronautical Service.

Any vertically polarised LF/MF radio transmitter will act as an NDB as the signal in theory, radiates in all directions. The advantage of the NDB for aeronautical use is the cone of silence vertically above the beacon which givies a precise overhead hence their use as airway markers before the VOR. Broadcast stations may also be used but their high power, modulation and variable polarisation can detract from the accuracy.

ADF is "Automatic" DF as opposed to Manual DF that was predominantly used on ships and early aircraft.

[Evo7]

Just to add, the disadvantage of NDBs is that they are more prone to error than VORs. For example, there are reflections from hills, coastal effects, night effects due to the movement of the ionosphere ... and a thunderstorm pumps out a lot of non-directional energy in the radio band, making it a rather effective NDB :)

[Noggin]

It is of course the ADF that suffers from the errors, not the NDB