Basic definitions related to codes

Question 1

Information rate is defined as

a. Information per unit time
b. Average number of bits of information per second
c. rH
d. All of the above

Answer 1

All of the above

Question 2

The mutual information

a. Is symmetric
b. Always non negative
c. Both a and b are correct
d. None of the above

Answer 2

Both a and b are correct

Question 3

In Alternate Mark Inversion (AMI) is

a. 0 is encoded as positive pulse and 1 is encoded as negative pulse
b. 0 is encoded as no pulse and 1 is encoded as negative pulse
c. 0 is encoded as negative pulse and 1 is encoded as positive pulse
d. 0 is encoded as no pulse and 1 is encoded as positive or negative pulse

Answer 3

0 is encoded as no pulse and 1 is encoded as positive or negative pulse

Question 4

Advantages of using AMI

a. Needs least power as due to opposite polarity
b. Prevents build-up of DC
c. May be used for longer distance
d. All of the above

Answer 4

All of the above

Question 5

Entropy is

a. Average information per message
b. Information in a signal
c. Amplitude of signal
d. All of the above

Answer 5

Average information per message

Question 6

The expected information contained in a message is called

a. Entropy
b. Efficiency
c. Coded signal
d. None of the above

Answer 6

Entropy

Question 7

Overhead bits are

a. Framing and synchronizing bits
b. Data due to noise
c. Encoded bits
d. None of the above

Answer 7

Framing and synchronizing bits

Question 8

Timing jitter is

a. Change in amplitude
b. Change in frequency
c. Deviation in location of the pulses
d. All of the above

Answer 8

Deviation in location of the pulses

Question 9

Probability density function defines

a. Amplitudes of random noise
b. Density of signal
c. Probability of error
d. All of the above

Answer 9

Amplitudes of random noise

Question 10

Regenerative repeaters are used for

a. Eliminating noise
b. Reconstruction of signals
c. Transmission over long distances
d. All of the above

Answer 10

All of the above

Question 11

Scrambling of data is

a. Removing long strings of 1’s and 0’s
b. Exchanging of data
c. Transmission of digital data
d. All of the above

Answer 11

Removing long strings of 1’s and 0’s

Question 12

The polarities in NRZ format use

a. Complete pulse duration
b. Half duration
c. Both positive as well as negative value
d. Each pulse is used for twice the duration

Answer 12

Complete pulse duration

Question 13

The channel capacity is

a. The maximum information transmitted by one symbol over the channel
b. Information contained in a signal
c. The amplitude of the modulated signal
d. All of the above

Answer 13

The maximum information transmitted by one symbol over the channel

Question 14

Pulse shaping is done

a. to control Inter Symbol Interference
b. by limiting the bandwidth of transmission
c. after line coding and modulation of signal
d. All of the above

Answer 14

All of the above

Question 15

Roll – off factor is defined as

a. The bandwidth occupied beyond the Nyquist Bandwidth of the filter
b. The performance of the filter or device
c. Aliasing effect
d. None of the above

Answer 15

The bandwidth occupied beyond the Nyquist Bandwidth of the filter

Question 16

The interval of frequencies outside which the spectrum is zero is called as ________

a) null to null bandwidth
b) normalized bandwidth
c) absolute bandwidth
d) none of the mentioned

Answer 16

absolute bandwidth

Question 17

The characteristics of compressor in μ-law companding are

a. Continuous in nature
b. Logarithmic in nature
c. Linear in nature
d. Discrete in nature

Answer 17

Continuous in nature

Question 18

Impulse noise is caused due to

a. Switching transients
b. Lightening strikes
c. Power line load switching
d. All of the above

Answer 18

All of the above

Question 19

In coherent detection of signals,

a. Local carrier is generated
b. Carrier of frequency and phase as same as transmitted carrier is generated
c. The carrier is in synchronization with modulated carrier
d. All of the above

Answer 19

All of the above

Question 20

Synchronization of signals is done using

a. Pilot clock
b. Extracting timing information from the received signal
c. Transmitter and receiver connected to master timing source
d. All of the above

Answer 20

All of the above

Question 21

What is meant by aliasing effect?

Answer 21

Aliasing effect takes place when sampling frequency is less than Nyquist rate Under such condition, the spectrum of the sampled signal overlaps with itself. Hence higher frequencies take the form of lower frequencies. This interference of the frequency components is called as aliasing effect.