Communication Engineering Set 12

Computer Science Engineering (CSE)

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This set of Communication Engineering Multiple Choice Questions & Answers (MCQs) focuses on Communication Engineering Set 12

Q1 | In comparison to stack algorithm, Fano’s algorithm is simpler.
  • true
  • false
Answer: false
Explaination:
in comparison to fano’s
Q2 | Which of the following is not an error correction and detection code?
  • block code
  • convolutional codes
  • passive codes
  • turbo codes
Answer: passive codes
Explaination:
there are three basic types of error correction and detection codes. they are block codes, convolutional codes and turbo codes. a channel coder operates on digital message data by encoding the source information into a code sequence.
Q3 | Which decoding method involves the evaluation by means of Fano’s algorithm?
  • maximum likelihood decoding
  • sequential decoding
  • maximum a priori
  • minimum mean square
Answer: sequential decoding
Explaination:
fano’s algorithm involves sequential decoding. it searches for the most probable path through the trellis by examining one path at a time.
Q4 | In Viterbi’s algorithm, the selected paths are regarded as                      
  • survivors
  • defenders
  • destroyers
  • carriers
Answer: survivors
Explaination:
in viterbi’s algorithm, the selected paths are regarded as survivors. the path thus defined is unique and corresponds to the decoded output.
Q5 | Pseudorandom signal                  predicted.
  • can be
  • cannot be
  • maybe
  • none of the mentioned
Answer: can be
Explaination:
random signals cannot be predicted whereas pseudorandom sequence can be predicted.
Q6 | The properties used for pseudorandom sequence are
  • balance
  • run
  • correlation
  • all of the mentioned
Answer: all of the mentioned
Explaination:
the three basic properties that can be applied for pseudorandom sequence are balance, run and correlation properties.
Q7 | The shift register needs to be controlled by clock pulses.
  • true
  • false
Answer: true
Explaination:
the shift register operation is controlled by clock pulses.
Q8 | A linear feedback shift register consists of
  • feedback path
  • modulo 2 adder
  • four stage register
  • all of the mentioned
Answer: all of the mentioned
Explaination:
a linear feedback shift register
Q9 | If the initial pulse of 1000 is fed to shift register, after how many clock pulses does the sequence repeat?
  • 15
  • 16
  • 14
  • 17
Answer: 15
Explaination:
if the initial pulse 1000 is given to shift register, the foregoing sequence repeats after 15 clock pulses.
Q10 | The sequences produced by shift register depends on
  • number of stages
  • feedback tap connections
  • initial conditions
  • all of the mentioned
Answer: all of the mentioned
Explaination:
the sequences produced by shift register depends on the number of stages, the feedback tap connections and initial conditions.
Q11 | For maximal length sequence, the sequence repetition clock pulses p is given by
  • 2n + 1
  • 2n -1
  • 2n
  • none of the mentioned
Answer: 2n -1
Explaination:
for maximal length sequence, produced by n stage linear feedback shift register the sequence repetition clock pulses p is given by 2n -1 .
Q12 | For any cyclic shift, the auto-correlation function is equal to
  • 1/p
  • -1/p
  • –p
  • p
Answer: -1/p
Explaination:
for any cyclic shift the auto- correlation function is equal to -1/p.
Q13 | Which method is better?
  • to share same bandwidth
  • to share different bandwidth
  • to share same & different bandwidth
  • none of the mentioned
Answer: to share different bandwidth
Explaination:
if the jammer noise shares the same bandwidth, the result could be destructive.
Q14 | Pulse jammer consists of
  • pulse modulated excess band noise
  • pulse modulated band-limited noise
  • pulse width modulated excess band noise
  • pulse width modulated band-limited noise
Answer: pulse modulated band-limited noise
Explaination:
pulse jammer consists of pulse modulated band-limited noise.
Q15 | Which are the design options for anti jam communicator?
  • time diversity
  • frequency diversity
  • special discrimination
  • all of the mentioned
Answer: all of the mentioned
Explaination:
the design options for anti-jam communicator are time diversity, frequency diversity and special discrimination.
Q16 | The ratio (J/S)reqd gives the measure of
  • vulnerability to interference
  • invulnerability to interference
  • all of the mentioned
  • none of the mentioned
Answer: invulnerability to interference
Explaination:
the ratio (j/s)reqd gives the measure of how invulnerable the system is to interference.
Q17 | The system should have
  • larger (j/s)reqd
  • greater system’s noise rejection capability
  • larger (j/s)reqd & greater system’s noise rejection capability
  • none of the mentioned
Answer: larger (j/s)reqd & greater system’s noise rejection capability
Explaination:
the system will be efficient if it has greater (j/s)reqd and larger system’s noise rejection capability.
Q18 | The broadband jammer jams the entire
  • w
  • wss
  • w & wss
  • none of the mentioned
Answer: wss
Explaination:
the broadband jammer or wide-band jammer is the one which jams the entire wss with its fixed power.
Q19 | To increase error probability, the processing gain should be
  • increased
  • decreased
  • exponentially increased
  • exponentially decreased
Answer: increased
Explaination:
in a system, to increase the error probability the processing gain should be increased.
Q20 | Which jamming method produces greater degradation?
  • broadband jamming
  • partial jamming
  • broadband & partial jamming
  • none of the mentioned
Answer: partial jamming
Explaination:
greater degradation is possible more with partial jamming than broadband jamming.
Q21 | The jammer which monitors a communicator’s signal is known as
  • frequency follower jammers
  • repeat back jammers
  • frequency follower & repeat back jammers
  • none of the mentioned
Answer: frequency follower & repeat back jammers
Explaination:
the smart jammers which monitor a communicator’s signals is known as frequency follower or repeat back jammers.
Q22 | DS/BPSK includes
  • despreading
  • demodulation
  • despreading & demodulation
  • none of the mentioned
Answer: despreading & demodulation
Explaination:
ds/bpsk is a two step precess which includes despreading and demodulation.
Q23 | In direct sequence process which step is performed first?
  • de-spreading
  • demodulation
  • despreading & demodulation
  • none of the mentioned
Answer: de-spreading
Explaination:
in direct sequence process, de- spreading correlator is followed by a modulator.
Q24 | Chip is defined as
  • shortest uninterrupted waveform
  • largest uninterrupted waveform
  • shortest diversion
  • none of the mentioned
Answer: shortest uninterrupted waveform
Explaination:
a chip is defined as the shortest uninterrupted waveform in the system.
Q25 | Processing gain is given as
  • wss/r
  • rch/r
  • wss/r & rch/r
  • none of the mentioned
Answer: wss/r & rch/r
Explaination:
processing gain is given as both as the ratio of the minimum bandwidth of the data to data rate and also the by the ratio of code chip rate and data rate as minimum bandwidth is approximately equal to code chip rate.
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