robustlifestyles.com – MCQs, Mock Tests | Electrical measurements Digital Communications MCQs set-9

Syndrome is calculated by

1. HT/r
2. rHT
3. rH
4. None of the mentioned

✅ Correct Answer: 2

The _____ of the code-word is the number of non zero elements.

1. Size
2. Weight
3. Distance
4. Subspace

✅ Correct Answer: 2

Some examples of linear codes

1. Hamming code
2. Reed-Solomon code
3. Parity code
4. All of the mentioned

✅ Correct Answer: 4

The measure of the amount of redundancy is given by

1. Code size
2. Code weight
3. Code rate
4. Minimum distance

✅ Correct Answer: 3

The number of k bit shift over which a single information bit influences the encoder output is given by

1. Code rate
2. Constraint length
3. Code length
4. Code weight

✅ Correct Answer: 2

The method used for representing convolution encoder are

1. Connection pictorial
2. State diagram
3. Tree diagram
4. All of the mentioned

✅ Correct Answer: 4

Periodic truncation is done by

1. Appending zero to end of the input data sequence
2. Appending zero to the beginning of the input data sequence
3. Appending oneâ€™s to end of the data sequence
4. Appending oneâ€™s to beginning of the data sequence

✅ Correct Answer: 1

Finite state machines have

1. Past memories also
2. Only present and future memories
3. Only future memories
4. Only present memories

✅ Correct Answer: 1

How many number of transitions can be made at each bit time?

1. One
2. Two
3. Three
4. Half

✅ Correct Answer: 2

In trellis diagram, the number of nodes ______ at successive branching.

1. Increases by 1
2. Doubles
3. Triples
4. None of the mentioned

✅ Correct Answer: 2

Example for convolution encoder state diagram is

1. Tree diagram
2. Trellis diagram
3. Tree & Trellis diagram
4. None of the mentioned

✅ Correct Answer: 3

In maximum likelihood decoding technique, the likelihood function compares the

1. Joint probabilities
2. Individual probabilities
3. Conditional probabilities
4. None of the mentioned

✅ Correct Answer: 3

In maximum likelihood detector the error probability is

1. Maximum
2. Minimum
3. Zero
4. None of the mentioned

✅ Correct Answer: 2

For a binary code, the maximum number of possible sequence made up of L branch words is

1. L2
2. 2L
3. 2L
4. L/2

✅ Correct Answer: 2

If the quantization level of a demodulator output is ________ then it is called as soft decision decoding.

1. Equal to 2
2. More than 2
3. Less than 2
4. None of the mentioned

✅ Correct Answer: 2

Soft decision decoding requires

1. Less memory
2. More memory
3. More speed
4. None of the mentioned

✅ Correct Answer: 2

A binary symmetric channel is a

1. Discrete memoryless channel
2. Continuous memoryless channel
3. Discrete memory channel
4. Continuous memory channel

✅ Correct Answer: 1

Binary symmetric channel is hard decision channel.

1. True
2. False
3.
4.

✅ Correct Answer: 1

Gaussian channel is a hard decision channel.

1. True
2. False
3.
4.

✅ Correct Answer: 2

Branch word synchronization is the process of determining the

1. Beginning of received sequence
2. Beginning of transmitted sequence
3. End of received sequence
4. End of transmitted sequence

✅ Correct Answer: 1

Which distance is related to the error correcting capability of the code?

1. Maximum distance
2. Minimum distance
3. Maximum & Minimum distance
4. None of the mentioned

✅ Correct Answer: 2

A catastrophic error is an event whereby ______ number of code symbol error causes _______ number of decoded data error bits.

1. Finite, finite
2. Finite, infinite
3. Infinite, finite
4. Infinite, infinite

✅ Correct Answer: 2

A code should be selected such that it should

1. Not have catastrophic error propagation
2. Have minimum free distance
3. All of the mentioned
4. None of the mentioned

✅ Correct Answer: 1

The error correcting capability of a code scheme increases as the

1. Number of channel symbols per information bit increases
2. Bandwidth increases
3. Information per bit increases
4. All of the mentioned

✅ Correct Answer: 4

Which has a limited resolution?

1. Hard decision decoder
2. Soft decision decoder
3. Hard & Soft decision decoder
4. None of the mentioned

✅ Correct Answer: 2

Which parameter is used in soft decision algorithm?

1. Euclidean distance
2. Euclidean distance squared
3. Euclidean distance & distance squared
4. None of the mentioned

✅ Correct Answer: 3

Which factor is desirable?

1. Minimum correlation
2. Maximum correlation
3. Maximum distance
4. None of the mentioned

✅ Correct Answer: 2

Soft decision results in

1. Increase in complexity
2. Decrease in storage
3. Increase in complexity & Decrease in storage
4. None of the mentioned

✅ Correct Answer: 1

A feedback decoder makes hard decision.

1. True
2. False
3.
4.

✅ Correct Answer: 1

The look ahead length L is given by

1. m+1
2. m-1
3. (m+1)/2
4. 1-m

✅ Correct Answer: 1

On increasing L

1. Coding gain increases
2. Complexity increases
3. Coding gain & Complexity increases
4. None of the mentioned

✅ Correct Answer: 3

Reed Solomon codes are

1. Non binary
2. Cyclic
3. Non binary & Cyclic
4. None of the mentioned

✅ Correct Answer: 3

The minimum distance for Reed Solomon code is given by

1. n+k+1
2. n-k+1
3. 1-n-k
4. 1+n-k

✅ Correct Answer: 2

R-S codes have

1. High code rate
2. Low redundancy
3. High code rate & Low redundancy
4. None of the mentioned

✅ Correct Answer: 3

Greater the redundancy greater will be the error correcting capability.

1. True
2. False
3.
4.

✅ Correct Answer: 1

A primitive element are those which yield ______ when raised to higher order exponents.

1. All zero elements
2. Non zero elements
3. Unity elements
4. None of the mentioned

✅ Correct Answer: 2

If the inversion was performed correctly, then the multiplication of the original matrix with the inverted matrix should yield identity matrix. This is known as

1. Identity theorem
2. Safety theorem
3. Multiplication theorem
4. Inversion theorem

✅ Correct Answer: 2

Compact disc is used for

1. Digital storage
2. Reproduction of audio signals
3. Digital storage & Reproduction of audio signals
4. None of the mentioned

✅ Correct Answer: 3

Sources of channel errors are

1. Finger prints
2. Air bubbles
3. Unwanted particles
4. All of the mentioned

✅ Correct Answer: 4

The CIRC error control scheme includes

1. Correction
2. Concealment
3. Correction & Concealment
4. None of the mentioned

✅ Correct Answer: 3

Decoding step consists of

1. De-interleaving
2. Decoding
3. De-interleaving & Decoding
4. None of the mentioned

✅ Correct Answer: 3

The ______ the error correcting capability used, the _____ will be the erasure correcting capability.

1. Larger, smaller
2. Smaller, larger
3. Smaller, smaller
4. Larger, larger

✅ Correct Answer: 1

In interpolation

1. New samples are added
2. Unreliable samples are removed
3. New samples are added & Unreliable samples are removed
4. None of the mentioned

✅ Correct Answer: 3

The channel that exhibits multi-path fading

1. Has memory
2. Exhibits mutually dependent signal transmission impairments
3. Received signal will be distorted
4. All of the mentioned

✅ Correct Answer: 4

Separating the symbols makes the channel memory-less.

1. True
2. False
3.
4.

✅ Correct Answer: 1

The minimum end to end delay in block interleaving is

1. 2MN+2M+2
2. 2MN-2M+2
3. 2MN-2M-2
4. 2MN+2M-2

✅ Correct Answer: 2

A concatenated code uses

1. One level of coding
2. Two levels of coding
3. Three levels of coding
4. None of the mentioned

✅ Correct Answer: 2

A concatenated code has

1. Low error rate
2. High complexity
3. Low error rate & High complexity
4. None of the mentioned

✅ Correct Answer: 1

The performance of non binary concatenated code depends on

1. Bit errors
2. Symbols errors
3. Bit & Symbols errors
4. None of the mentioned

✅ Correct Answer: 2

Concatenated code is an example of

1. Error detecting code
2. Error correcting code
3. Error detecting & correcting code
4. None of the mentioned

✅ Correct Answer: 2

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