NDB And ADF

Question 1

Frequency range of ADF?

Answer 1

190 KHz - 1750 KHz

Question 2

Primary method of signal propagation of ADF?

Answer 2

Surface waves

Question 3

Range of ADF over land and water?

Answer 3

300 NM over land 600 NM over sea

Question 4

What does the loop aerial do? What can’t it show by itself?

Answer 4

If the incoming wave from the ADF station is at any other angle other than at 90 degrees to the loop, an ac current will be induced in the loop as the phase of the wave will be different on each side. If the loop is rotated so that no ac is induced, the incoming wave must either be directly behind or in front of the loop. It cannot tell weather the signal is coming from behind or in front as there are two null points in the polar diagram

Question 5

What does the sense aerial do? What is the name of the polar diagram produced when combined with loop aerial?

Answer 5

Receives signals from all directions and resolves the ambiguity of the two null points of loop aerial by combining reception characteristics Cardioid polar diagram

Question 6

What is the most primitive form of ADF cockpit indicator called? (2 names)

Answer 6

Fixed card or RBI

Question 7

What is the moving card ADF?

Answer 7

Aircraft heading can be manually set at the top of the instrument so the head of the needle indicates bearing to the station and the tail indicates the radial

Question 8

What is an RMI?

Answer 8

Aircraft magnetic heading is automatically set on the instrument from a remote indicating compass and point of needle automatically displays bearing to station and tail indicates radial

Question 9

If the heading info fed to an RMI is incorrect, will the bearing to the station be correct and will the relative bearing be correct?

Answer 9

Bearing to station will be wrong but relative bearing will be correct

Question 10

What is the BFO for?

Answer 10

Used to make the A1A morse ident signal audible

Question 11

ICAO requirement is accuracy of +/-… degrees with signal to noise ratio of no less than …

Answer 11

6 degrees

3:1

Question 12

what create the largest unpredictable errors in ADF and thus greatest navigational uncertainty?

Answer 12

thunderstorms

Question 13

What is night effect?

Answer 13

possible for weak sky waves to be returned at night when the ionosphere is less dense and attenuation least. These sky waves tend to strike the top of the loop aerial and induce a current flow where none would otherwise be present. The null is no longer sharply defined and the needle hunts, reducing bearing accuracy

Question 14

night effect most likely when?

Answer 14

dawn or dusk

Question 15

What is station interference?

Answer 15

a similar symptom to night effect but caused because the long ground waves of LF and MF bands occasionally overlap on similar frequencies. Does not cause errors during day time if the stations are only used in the protected range but can at night when returning sky waves cause rogue signals at considerable range. Problem detected the same as night effect and possible two idents audible

Question 16

what is a bandpass switch?

Answer 16

reduces received bandwidth to reduce station interference ny listening to a sharper band

Question 17

what is quadrantal error?

Answer 17

the wave front can be distorted by the EMF in the aircraft metallic structure as it approaches the aerial. Called Quadrantal because the effect is worst for signals arriving from 45 degrees and 135 degrees left and right of nose (the four quadrants). Error small and predictable and normally compensated for with any residual error recorded on Quadrantal error card kept near the instrument. Modern receivers completely remove it

Question 18

what is dip?

Answer 18

occurs when the sense aerial is masked by the loop aerial. It gives large bearing errors, only occurs in a turn and is greatest when the NDB is on a relative bearing of 45 and 135 left and right of the nose

Question 19

protected range of a beacon highly unusual to be greater than …

Answer 19

200nm

Question 20

Max range of NDB over land formula =

Answer 20

2 x sqaure root of power

Question 21

Max range of NDB over water formula =

Answer 21

3 x square root of power

Question 22

Locator beacons usually located?

Range?

Power?

Answer 22

low powered beacons with a rated of coverage of between 10 and 25 NM and power output of 15 to 40 watts. Usually co-located with an ILS outer marker

Question 23

ADF needle indicates what Q direction?

Answer 23

QDM

Question 24

When NDB tracking allowing for drift, the angle between heading and the needle head shold be the same as…

Answer 24

drift

Question 25

Tail of an ADF needle indicates what Q direction?

Answer 25

QDR (beacon radial)

Question 26

When NDB tracking If heading is out by more than drift, the effect is to…

Answer 26

push the head of the needle away from the heading bug

Question 27

When tracking away from an NDB with wrong wind correction angle, the effect on the needle tail is…

Answer 27

pulls towards heading

Question 28

To place the aircraft on a chosen bearing from/to a beacon, the rule is…

Answer 28

push the head and pull the tail

Question 29

When flying an NDB approach the pilot has to fly the required bearing to an accuracy of +/- … to be considered established on the bearing

Answer 29

5 degrees