Communication Systems - Section 1

Directions to Solve

Communication Systems - Section 1

Counterpoise is used in coils having

A.	Counterpoise is used in coils having
B.	low resistivity
C.	medium resistivity
D.	both (b) and (c)

Answer: Option A

Explanation:

Counterpoise is a horizontally buried wire used to provide low grounding resistance in high resistivity soils.

In CCIR-B system, the time between start of one H syn. pulse and next is

A.	64 μs
B.	6.4 μs
C.	640 μs
D.	0.64 μs

Answer: Option A

Explanation:

The frequency of H pulses is 15625 Hz.

Hence .

When the channel is noisy, producing a conditional probability of error p = 0.5; the channel capacity and entropy function would be, respectively,

A.	1 and 1
B.	1 and 0.5
C.	0.5 and 1
D.	0 and 1

Answer: Option D

Explanation:

Push pull amplifier is

A.	voltage amplifier
B.	current amplifier
C.	power amplifier
D.	none of the above

Answer: Option C

Explanation:

Push pull is a power amplifier.

Which of the following is taken as reference antenna for directive gain?

A.	Half wave dipole
B.	Elementary doublet
C.	Isotropic
D.	Infinitesimal dipole

Answer: Option C

Explanation:

Isotropic antenna is one which radiates equally in all directions. It is a standard reference antenna.

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:

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.

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.

Communication Systems - Section 1

Communication Systems - Section 1

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