Avionics

Question 1

Name of on-Board equipment to get NDB bearing

Answer 1

ADF - Automatic Direction Finder

Question 2

What kind of antennas used for onboard equipment?

Answer 2

Loop antenna
Sense antenna

Question 3

Indication errors: cause and effects

Answer 3

Difference in Range: Ground wave had longer range over wet surfaces than over dry surfaces, leading to mistakingly receiving signals from the wrong station

Fading: Interference between ground and sky wave or different sky waves. Leads to errors or destructive interference

Twilight/Night effect
Signal is reflected at the ionosphere, especially during night/twilight, changing polarisation. Causes needle oscillation/ unreliable indications

Statics and Thunderstorm effect
Static charge and discharge in Cu/CB clouds, interfering with the signal. Unreliable indication and possible damage to receiver

Mountain effect: Signal is diffracted or reflected at a mountain, causing false indications.

Bank error: Loop antenna is moved away from its minimum position in a bank, causing offset in direction of turn.

Shoreline effect: Signal is refracted at shoreline due to different elec. conductivity, causing offset.

Quadrantal error:
Signal hits a/c metal parts, especially in 45deg directions, causing deviations.

Question 4

What is INS?

Answer 4

Inertial Navigation System

Question 5

INS components & working principle

Answer 5

• gyro stabilised reference platform
• accelerometers
• processing unit
• indicator

Refers to a fixed starting point and measures direction of movement and acceleration to calculate position via dead reckoning

Question 6

Which effect is an LDNS using?

Answer 6

Light Doppler Navigation System

Uses doppler effect (frequency shift due to relative motion between transmitter and receiver)