ADF/NDB

Question 1

What is the normal mode position for automatic direction finding on the ADF?

Answer 1

ADF/COMP (compass on older systems)

Question 2

State the range of frequencies usually employed by NDB’s.

Answer 2

Between 200-400KHz but up to 1750KHz in some instances

Question 2

List at least three factors effecting NDB accuracy

Answer 2

Night Effect
Coastal Refraction
Mountain Effect
Precipitation Static
Thunderstorms

Question 3

NDB coverage and range is reduced at night due to night effect when ____nm to ____nm from the station

Answer 3

when 70nm to 80nm from the station

Question 4

NDB ground stations transmit a vertically polarised signal on a single frequency in (one direction, all directions, 360 different radials)

What is the correct answer?

Answer 4

all directions

Question 5

The main purpose of the ADF sense aerial is to…

Answer 5

resolves the ambiguity of the two null positions, it creates only one null position

Question 5

When passing overhead an NDB station the ident volume in the headset will (increase,decrease) until overhead where it will significantly reduce or mute for a brief period

What is the correct answer?

Answer 5

increase

Question 6

NDB signals can suffer from coastal refraction. When the signals cross a coastline at a (oblique, right) angle they are not suscepted to bending

What is the correct answer?

Answer 6

right angle

Question 7

NDB coastal refraction causes signals to bend toward (land mass, water,)

What is the correct answer?

Answer 7

toward land mass

Question 8

List the basic components of an aircraft ADF

Answer 8

ADF Receiver
Loop Antenna Aerial
Sense Aerial
Control Panel
Instrument (RBI or RMI)

Question 8

The fixed-loop ADF uses two loop antenna’s, it (does, does not) require a sense antenna

What is the correct answer?

Answer 8

**Does **require a sense antenna

Question 8

Prior to using an NDB beacon for navigation, each time an NDB is tuned you must check: (list all three)

Answer 8

Correct frequency
Identify NDB by listening to the identification code
Bearing needle is indicating the expected bearing

Question 10

Max voltage will be induced in the ADF Loop antenna when the loop antenna is (face on to the wave, 45° angle to the wave, 90° parallel to the wave)

What is the correct answer?

Answer 10

90° parallel to the wave

Question 11

With regard to NDB coastal refraction, the ____ the angle the greater the refraction

Answer 11

the shallower the angle the greater the refraction

Question 12

If you are experiencing needle fluctuation at night it maybe due to night effect, if available you could..

Do what to remedy the situation? list two options

Answer 12

**Use another beacon within the 70-80nm skip distance

Use another beacon of significantly lower frequency**

Question 14

List the advantages of the fixed-loop ADF

Answer 14

Fewer moving parts
More aerodynamic installation possible
Is more trouble free

Question 15

When an NDB signal is directly straight ahead of the aircraft nose, the ADF needle points (9 o’clock, 12 o’clock, 6 o’clock) relative

What is the correct answer?

Answer 15

12 o’clock relative

Question 16

NDB night effect is caused by the aircraft ADF receiving both surface waves and **(direct waves, sky waves, VHF waves) **

What is the correct answer?

Answer 16

surface waves and sky waves

Question 17

When passing overhead an NDB you should expect the instrument needle to…

Answer 17

show large swings from side to side or rotate 180° relative and then settle down

Question 18

When the ANT/REC/VOICE function on the ADF control panel is selected it (only uses the sense aerial, only uses the loop aerial, uses both aerials)

What is the correct answer?

Answer 18

Uses only the sense aerial

Question 20

Factors effecting operational range of an NDB are: (list at least three)

Answer 20

Transmit Power
NDB Frequency
Time of Day
Type or Surface
Receiver Efficiency

Question 21

When using the LOOP function of the ADF which aerial is disabled?

Answer 21

The Sense aerial is disabled

Question 22

List the common options available to reduce or remedy fluctuating NDB signals caused by mountain effect

Answer 22

**Increase in altitude

Use a higher frequency NDB**

Question 24

NDB range will normally be greater over (land,water) than over (land,water)

Which combination gives the correct answer?

Answer 24

NDB range will normally be greater over water than over land

Question 25

When in the vicinity of an active thunderstorm the ADF will (not be effected, show minor deviation, become totally unreliable)

What is the correct answer?

Answer 25

**become totally unreliable

(as it points to the source of sparatic radio energy generated by the thunderstorm)**

Question 26

Describe the BFO/CW Mode of the ADF

Answer 26

(Beat Frequency Oscillator or Continuous Wave) Used to identify un modulated, interupted transmissions to identify the NDB station. It is not used in NZ and not used for navigation

Question 27

What is the purpose of the ADF VOICE function? (also called ANT or REC)

Answer 27

It is used to provide clearer audio of the identification station, no directional information from ADF needle is given

Question 28

When a null is detected by the ADF Loop antenna (max voltage, no voltage) will be induced because the waves hit the antenna at the same time and phase

What is the correct answer?

Answer 28

No Voltage

Question 29

Describe the use of the ADF LOOP function

Answer 29

Used to manually control the loop through a crank handle or switch and maybe used in difficult reception conditions such as static or extreme range, it is rotated manually to the null position.

Question 30

The lower the NDB frequency the (shorter, longer) the range

What is the correct answer?

Answer 30

longer the range