Direction Finding (VDF + ADF)

Question 1

What is DF and RDF?

Answer 1

The measurements of the direction from which a received signal was transmitted.

Question 2

What is a true radio bearing?

Answer 2

A radio bearing for which the reference is true north.

Question 3

What is a magnetic radio bearing?

Answer 3

A radio bearing for which the reference direction is magnetic north

Question 4

How does the DF ground equipment display bearing information?

Answer 4

By LED Cathode Ray Tube (CRT) in the compass rose and bearing readout

Question 5

The accuracy fir tolerance fir bearings for DF is categorised as?

Answer 5

Class A: +/- 2 degrees
Class B: +/- 5 degrees
Class C +/- 10 degrees
Class D: worse than C

Question 6

Will each unit have a classification for their DF?

Answer 6

Yes

Question 7

What can a DF be used for?

Answer 7

To assist a pilot who may be temporarily uncertain of their position

Question 8

List the Q codes

Answer 8

QTE

QDR

QDM

Question 9

What is QTE?

Answer 9

True bearing of an aircraft in relation to the direction finding station/specified point

Question 10

What is QDR?

Answer 10

The magnetic bearing of an aircraft in relation to the direction finding station or other specified point

Question 11

What is QDM?

Answer 11

The magnetic heading to steer (with no wind) to make the direction finding station/specific point

Question 12

What is triangulation?

Answer 12

A way that pilots can establish their approximate positions by obtaining two or more bearing from separate DF stations and plotting the point at which the bearings intercept.

Question 13

What is homing?

Answer 13

The procedure of using the DF equipment at your radio station with the radio bearing of the aircraft transmission whereby the aircraft proceeds continuously towards the station following bearings from your DF equipment.

Question 14

What are the 3 Conditions when a DF station can refuse to give bearings/headings/positions?

Answer 14

1) Conditions unsatisfactory
2) when bearings do not fall within calibrated limits of the station
3) When to do so would monopolise the frequency

Question 15

What is radio bearing?

Answer 15

The angle(s) between the apparent direction of a definite source of emission of radio waves and a reference direction as determined at DF station

Question 16

What frequency band does the ADF operate in?

Answer 16

Medium Frequency- 300KHz to 3MHz

Question 17

What is an ADF?

Answer 17

A tuneable receiver fitted inside the aircraft.

Question 18

What does the ADF Display?

Answer 18

Displays a relative bearing in relation to the aircraft’s heading using a pointer on a relative bearing indicator (RBI).

Question 19

What aerial receives signal from the ground based equipment?

Answer 19

Loop aerial

Question 20

What is an NDB

Answer 20

An omni-directional Transmitter

Question 21

What waveband does it operate in?

Answer 21

LF (not in the uk
MF band (190 to 1750KHz)

Question 22

A NDB continuously transmits an audio tone with a morse signal identifier.
True or False?

Answer 22

True.

Question 23

What is the average radius of an NDB?

Answer 23

Between 10 and 500nm

Question 24

What are high powered NDBs used for?

Answer 24

Long range navigation on or off airways

Question 25

What are low powered NDBs used for?

Answer 25

Used as airfields approach aids, known as locator beacons.

Question 26

Do low powered NDBs have a limited range?

Answer 26

True.

Question 27

What is a Radio Magnetic Indicator (RMI)?

Answer 27

An arrow superimposed onto the compass rose. | A QDM can read straight from the pointer.

Question 28

Can a RMI house more than one arrow simultaneously?

Answer 28

Yes; to display bearing information to more than one beacon.

Question 29

What does the radio bearing indicator (RBI) continuously display?

Answer 29

The relative bearing in relation to the aircraft’s heading.

Question 30

List the NDB Errors (all 7 of them)

Answer 30

1) Static Interference 2) Station Interference 3) Mountain Effect 4) Costal Refraction 5) Night Effect 6) Quadrantal Error 7) Lack of System Malfunction

Question 31

What is static interference?

Answer 31

Thunderstorms or heavy rain cause static interference. ADF needle will point at the centre of an active Thunderstorm.

Question 32

What is station interference?

Answer 32

Large bearing errors caused by interference from transmitter operating on similar frequency.

Question 33

What is mountain Effect?

Answer 33

LF and MF are surface waves and are reflected by any high ground .

Question 34

What is costal refraction?

Answer 34

Faster over the sea than land. Further inland the NDB beacon the greater the bearing error.

Question 35

What is night Effect?

Answer 35

Severe bearing errors are most likely to occur at sunrise and sunset. Changes in ionosphere at night cause interference from transmissions

Question 36

Why is quadrantal error?

Answer 36

Airframe on an aircraft reflects/refracts and re-flexes radio waves. NDB strong with weaker signal distorted by fuselage. Maximum error when signal arrives at aircraft’s quadrantal point.

Question 37

What is lack of system malfunction?

Answer 37

Components/systems failure difficult to detect, no failure warning device. Constant monitoring of system required.

Question 38

What are the advantages of NDB?

Answer 38

MF not limited to line of sight | Range dependent on power of NDB

Question 39

What are he disadvantages of NDB?

Answer 39

Not as accurate at VOR Subject to errors (costal; static; mountain)