Electronics and Communication Engineering - Communication Systems

41. 

A generator is feeding power to a transmission line of characteristic impedance Z0. The line is terminated in impedance ZL. Standing waves will be set up if

A. ZL = Z0
B. ZL < Z0
C. ZL > Z0
D. both (b) and (c)

Answer: Option D

Explanation:

Both the case, i.e., ZL > Z0 and ZL < Z0 give rise to standing waves.


42. 

In sound recording the degree of pre-emphasis is about 6 dB/ octave.

A. True
B. False

Answer: Option B

Explanation:

It erases the matter already existing on the tape.


43. 

Space wave may be a direct wave or wave reflected from earth.

A. True
B. False

Answer: Option B

Explanation:

Strength of space wave depends on distance as it suffers attenuation.


44. 

Radio broadcasts are generally

A. amplitude modulation
B. frequency modulation
C. both amplitude and frequency modulation
D. neither amplitude nor frequency modulation

Answer: Option B

Explanation:

Frequency modulation gives noise free reception and is used for radio broadcasts.


45. 

If the frequency of a wave 20 Hz, the time period is

A. 20 secs
B. 2 secs
C. 0.2 secs
D. 0.05 secs

Answer: Option D

Explanation:

.