Communication Systems - ECE Questions and Answers

Whatsapp
Facebook
Copy
Copy Text
Copy
Copy URL

The constellation diagram of a modem has four states as shown in the figure given below. What is the bit rate of this modem?

Two times its band rate

Four times its band rate

Same as band rate

Sufficient information is not given to give the answer

Whatsapp
Facebook
Copy
Copy Text
Copy
Copy URL

When the modulating frequency is doubled, the modulation index is halved and the modulating voltage remains constant. The modulation system is

phase modulation

none of the above

Whatsapp
Facebook
Copy
Copy Text
Copy
Copy URL

Vividh Bharti programme is transmitted in

short wave

medium frequency

all of the above

none of the above

Whatsapp
Facebook
Copy
Copy Text
Copy
Copy URL

In a Vidicon camera tube, the beam current is controlled by

grid G₁

grid G₂

grids G₁, G₂, G₃

grid G₂, G₃

Whatsapp
Facebook
Copy
Copy Text
Copy
Copy URL

Johnson noise is

white for all Practical application

always white

depends on temperature

never white

Whatsapp
Facebook
Copy
Copy Text
Copy
Copy URL

Which of the following is unlikely to happen when quantising noise is decreased in PCM?

Increased bandwidth

Increased channel noise

Increased number of standard levels

All of the above

Whatsapp
Facebook
Copy
Copy Text
Copy
Copy URL

For real and odd signals, the Fourier series coefficient a_n is

purely imaginary

purely real and even

purely imaginary and odd

purely real and odd

Whatsapp
Facebook
Copy
Copy Text
Copy
Copy URL

An amplitude modulated wave is
e = 50 (1 + 0.4 cos 1000 t + 0.3 cos 10000 t) cos 10⁷ t

0.5

0.3

0.7

0.4

Whatsapp
Facebook
Copy
Copy Text
Copy
Copy URL

The efficiency of a horn speaker is about

10%

40%

60%

80%