OGRAD 02.02 – Automatic Direction Finder (ADF)

 

Results

Q1. An aircraft is “homing” to a radio beacon whilst maintaining a relative bearing of zero. If the magnetic heading decreases, the aircraft is experiencing:

right drift

Q2. Flying in the vicinity of CB clouds and using ADF

All 3 answers are correct

Q3. A loop aerial, as used in the ADF, will

Receive a minimum or null signal from a transmitter when the plane of the loop is at right angles to the direction of the transmitter

Q4. Which of the following is the ICAO allocated frequency band for ADF receivers?

200-1750 kHz

Q5. Which of the following is likely to have the greatest effect on ADF accuracy?

Interference from other NDBs, particularly at night

Q6. Consider the following statements on the NDB transmitter:

It is very simple, being required to transmit only a carrier wave and an identification

Q7. ADF bearings by an aeroplane by day within the published protection range should be accurate to within a maximum error of:

+/- 5°

Q8. The heading read on a standard RMI is

The compass heading

Q9. An NDB transmits a signal pattern in the horizontal plane which is :

omnidirectional

Q10. The combination of the polar diagrams of the loop and the sense aerial results in

A cardoid polar diagram, having only one null or minimum

Q11. When using ADF, the sky-wave (night) effect

Is most dominant around dusk and dawn

Q12. An RMI indicates aircraft heading. To convert the RMI bearings of NDBs and VORs to true bearings the correct combination for the application of magnetic variation is:

NDB: aircraft position VOR: beacon position

Q13. Factors liable to affect most NDB/ADF system performance and reliability include:

static interference – night effect – absence of failure warning system

Q14. Errors caused by the effect of coastal refraction on bearings at lower altitudes are maximum when the NDB is:

inland and the bearing crosses the coast at an acute angle

Q15. In order to obtain an ADF bearing the:

signal must be received by both the sense and loop aerials

Q16. Of the bearing indicators available for use on ADFs, the most sophisticated one is

The Radio Magnetic Indicator

Q17. Given: Compass heading 270° Deviation 2°W Variation 30°E Relative bearing 316° What is the QDR?

044°

Q18. Using an ADF indicator of the manually rotateable card type

The card should be rotated so that the aircraft heading is at the top of the indicator

Q19. Homing on an NDB

Will in most situations result in frequent heading changes when approaching the NDB

Q20. Night Effect’ which causes loss of signal and fading, resulting in bearing errors from NDB transmissions, is due to:

skywave distortion of the null position and is maximum at dawn and dusk

Q21. The ADF reception loop is always used so that the electromotive force (EMF)

induced is zero

Q22. The basic information given by the ADF is

The relative bearing from the aircraft to the NDB

Q23. Some ADFs have a bandwidth control. Consider the following statements:

Broad or wide bandwidth should be selected when listening to music or voice

Q24. What is the wavelength of an NDB transmitting on 375 kHz?

800 m

Q25. A radio beacon has an operational range of 10 NM. By what factor should the transmitter power be increased in order to achieve an operational range of 20 NM?

Four

Q26. Which one of the following disturbances is most likely to cause the greatest inaccuracy in ADF bearings?

Local thunderstorm activity

Q27. The BFO selector on an ADF receiver is used to:

hear the IDENT of some NDB stations radiating a continuous wave signal

Q28. Quadrantal errors associated with aircraft Automatic Direction Finding (ADF) equipment are caused by:

signal bending by the aircraft metallic surfaces

Q29. There are two NDBs, one 20 NM inland, and the other 50 NM inland from the coast. Assuming that the error caused by coastal refraction is the same for both propagations, the extent of the error in a position line plotted by an aircraft that is over water will be:

greater from the beacon that is 50 NM inland

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