Exercise: Communication Systems

Questions for: Communication Systems

The EHT voltage in a picture tube of TV is
A:
about 1000 kV
B:
about 100 kV
C:
about 15 kV
D:
about 1 kV
Answer: C

EHT voltage is 1 kV for each diagonal inch of CRT screen.

📖
📝
💬
👁️
A 1000 kHz carrier wave modulated 40% at 40000 Hz is applied to a resonant circuit tuned to a carrier frequency and having Q = 140. What is the degree of modulator after transmission through the circuit?
A:
40%
B:
20%
C:
0.27
D:
0.54
Answer: C

m0 = m(1 + 4Q2δ2)1/2

.

📖
📝
💬
👁️
Which one of the following is true?
A:
Characteristic impedance of twin wire feeder and coaxial cable are nearly the. same
B:
The characteristic impedance of coaxial cable is more than that of twin wire cable
C:
The characteristic impedance of twin wire cable is more than that of coaxial cable
D:
The characteristic impedance of a twin wire feeder may be more or less than that of coaxial cable
Answer: C

Z0 for twin wire cable is about 300 ohms while that for coaxial cable is about 75 ohms.

📖
📝
💬
👁️
A balun transformer gives an impedance transformation of
A:
4 : 1
B:
2 : 1
C:
1 : 4
D:
1 : 2
Answer: A

Balun gives 4 : 1 impedance transformation and can be used to interconnect twin wire feeder cable to coaxial cable.

📖
📝
💬
👁️
At night the ionosphere can be considered to be consisting of
A:
D, E, F1 and F2 layers
B:
D, E, F1 layers
C:
D, E, F2 layers
D:
E and F2 layers
Answer: D

During night D layer is almost absent. Moreover F1 and F2 layers merge to form single F2 layer. Hence only D and F2 layers at night.

📖
📝
💬
👁️
Ad Slot (Above Pagination)
Quiz