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Channel Coding MCQs

Practice Channel Coding MCQs with four options, answers and explanations for focused Electronics & Telecommunication Engineering revision.

Question 5
Communication SystemsChannel Coding

For a systematic linear block code, a codeword contains?

  • AOnly parity bits
  • BOriginal information bits explicitly plus parity bits
  • COnly carrier samples
  • DNo redundancy
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Correct Answer: B. Original information bits explicitly plus parity bits
Explanation: In systematic form, the information bits appear unchanged in specified codeword positions and parity bits occupy the remaining positions.
Reference: Standard communication systems: systematic block code
Question 6
Communication SystemsChannel Coding

For an (n,k) block code, the code rate is?

  • An/k
  • Bk/n
  • Cn-k
  • D1/(n+k)
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Correct Answer: B. k/n
Explanation: A block code maps k information bits into n coded bits, so its rate is R=k/n.
Reference: Standard communication systems: code rate
Question 9
Communication SystemsChannel Coding

In polynomial representation of cyclic codes, multiplication by x followed by reduction modulo x^n-1 corresponds to?

  • AA cyclic shift
  • BAmplitude clipping
  • CSampling
  • DFrequency translation only
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Correct Answer: A. A cyclic shift
Explanation: Multiplication by x shifts polynomial coefficients; modulo x^n-1 wraps the end coefficient around, implementing a cyclic shift.
Reference: Standard communication systems: cyclic-code polynomial representation
Question 10
Communication SystemsChannel Coding

The main objective of channel coding is to?

  • ARemove every redundant bit
  • BIntroduce structured redundancy to improve error detection or correction
  • CSuppress the RF carrier only
  • DReduce sampling rate below Nyquist
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Correct Answer: B. Introduce structured redundancy to improve error detection or correction
Explanation: Channel coding deliberately adds controlled redundancy so the receiver can detect or correct transmission errors.
Reference: Standard communication systems: channel coding
Question 14
Communication SystemsChannel Coding

A convolutional encoder is characterized by the fact that its output depends on?

  • AOnly the present input bit
  • BPresent input and encoder memory state
  • COnly receiver noise
  • DCarrier amplitude alone
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Correct Answer: B. Present input and encoder memory state
Explanation: Convolutional coding has memory: coded outputs depend on the current input and previous input information stored in the encoder state.
Reference: Standard communication systems: convolutional coding
Question 15
Communication SystemsChannel Coding

The Viterbi algorithm is widely used for?

  • AMaximum-likelihood sequence decoding of convolutional codes
  • BAM envelope detection
  • CFM generation by reactance modulation
  • DAnalog source compression only
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Correct Answer: A. Maximum-likelihood sequence decoding of convolutional codes
Explanation: The Viterbi algorithm searches a trellis efficiently for the most likely transmitted state sequence of a convolutional code.
Reference: Standard communication systems: Viterbi decoding
Question 16
Communication SystemsChannel Coding

In a trellis representation of a convolutional code, a path through the trellis represents?

  • AA possible encoder state and output sequence over time
  • BOnly receiver bandwidth
  • CA single analog carrier cycle
  • DThermal-noise temperature
Report an error
Correct Answer: A. A possible encoder state and output sequence over time
Explanation: Each trellis path corresponds to a possible sequence of encoder state transitions and associated coded outputs.
Reference: Standard communication systems: convolutional-code trellis