Which circuit in FM receivers cancels or filters out noise? - Avionics MCQ

Aeronautical & Aerospace Engineering : Avionics - Quiz(MCQ)

Which circuit in FM receivers cancels or filters out noise?

A)

Filter circuits

B)

Limiter circuits

C)

Delimiter circuits

D)

Anti-noise circuits

Correct Answer : Limiter circuits

Explanation : The receivers in FM contain limiter circuits which restrict the amplitude of the received signal. The noise which only affects the amplitude of the signal causes variations in amplitude of the signal. The limiter circuit clips off any variation in amplitude to filter out most of the noise.

Recently Updated in Avionics Questions

Which of the following is true with respect to the bandwidth of a 2kHz audio signal and a 2kHz binary data?

A)

Bandwidth is higher for binary data than audio signals

B)

Bandwidth is higher for audio signals than binary data

C)

Bandwidth remains the same for both

D)

Bandwidth keeps increasing with time for the binary data

Correct Answer : Option (A) : Bandwidth is higher for binary data than audio signals

Explanation : Since binary data is transmitted in square waves or pulses, they are generally made up of numerous fundamental sine waves. This occupies a huge bandwidth as compared to audio signals which are analog in nature and usually comprise of a lesser number of sine waves.

What is the signal to noise ratio if the maximum allowable frequency deviation is 4kHz and the frequency deviation by noise is 156.42Hz?

A)

0.0364

B)

0.0391

C)

20.45

D)

25.75

Correct Answer : Option (D) : 25.75

Explaination : N/S = Frequency deviation by noise / maximum deviation = 156.42/4000 =0.0391
S/N = (N/S)^-1=25.57.

Calculate the phase difference by noise if the Signal to noise ratio is 7:2.

A)

8.21°

B)

13.65°

C)

15.366°

D)

17.5°

Correct Answer : Option (C) : 15.366°

Explanation : ?=sin^-1(N/S)=sin^-1(2/7)=sin^-1(0.265)=15.366°.

Advertisement