What happens to the phase lag in an actuator as the frequency is increased?

Aeronautical & Aerospace Engineering : Avionics - Quiz(MCQ)

Increases

Constant

Decreases

Cannot be determined

Correct Answer : Increases

Explanation : The response of the actuators at low frequencies is basically that of a low pass (or first-order) filter, but as the frequency increases the lags in the first stage actuation system become dominant. The output/input ratio falls at an increasing rate and the phase lag rapidly increases.

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Which one of the following is false with respect to fiber optic cables?

Costly

High speed

Less EM interference

Heavy compared to normal wires

Correct Answer : Option (D) : Heavy compared to normal wires

Explanation : Fiber optics weigh comparatively very low than normal wires. Wires require shielding from EMI which also adds up to the overall weight of the connectivity system. They also offer high speed data transfer and are relatively costly.

What type of multiplexing is used in optical fiber lines?

Time division multiplexing

wavelength division multiplexing

Code division multiplexing

Frequency division multiplexing

Correct Answer : Option (B) : wavelength division multiplexing

Explanation : Fibre optic data transmission use ‘wavelength division’ multiplexing whereby a single fibre can be used to transmit several channels of information as coded light pulses of different wavelengths (or colours) simultaneously. The individual data channels are then recovered from the optically mixed data by passing the light signal through wavelength selective passive optical filters which are tuned to the respective wavelengths. WDM has a very high integrity as the multiplexed channels are effectively optically isolated.

Where was the first Fly-By-Light system used?

Spacecrafts

Airships

Fighter aircraft

Bomber Aircraft

Correct Answer : Option (B) : Airships

Explanation : Non-rigid airships may be acquiring a new lease of life as long duration platforms for airborne radar surveillance systems. The airship is able to carry a large high power radar antenna within its envelope and is able to remain airborne for several days. Since the antenna could severely interfere with FBW systems FBL system was used.