A. C = W log2 ( 1+S/N )
B. C = 2W log2 ( 1+S/N )
C. C = W log2 ( 1-S/N )
D. C = W log10 ( 1+S/N )
Answer: A
The capacity relationship from the Shannon-hartley capacity theorem is given by C = W log2 ( 1+S/N ).
3. Which parameter is called as Shannon limit?
A. PB/N0
B. EB/N0
C. EBN0
D. None of the mentioned
Answer: B
There exists a limiting value for EB/N0 below which they can be no error-free communication at any information rate. This EB/N0 is called as Shannon limit.
4. Entropy is the measure of
A. Amount of information at the output
B. Amount of information that can be transmitted
C. Number of error bits from the total number of bits
D. None of the mentioned
Answer: A
Entropy is defined as the average amount of information per source output.
5. Equivocation is the
A. Conditional entropy
B. Joint entropy
C. Individual entropy
D. None of the mentioned
Answer: A
Shannon uses a correction factor called equivocation to account for uncertainty in the received signal. It is defined as the conditional entropy of the message X given Y.
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6. For an error-free channel, the conditional probability should be
A. Zero
B. One
C. Equal to the joint probability
D. Equal to individual probability
Answer: A
For an error-free channel, the conditional probability should be zero because having received Y there is complete certainty about the message X.
7. Average effective information is obtained by
A. Subtracting equivocation from entropy
B. Adding equivocation with entropy
C. Ratio of number of error bits by the total number of bits
D. None of the mentioned
Answer: A
According to Shannon, the average effective information is obtained by subtracting the equivocation from the entropy of the source.
8. Turbo codes are
A. Forward error correction codes
B. Backward error correction codes
C. Error detection codes
D. None of the mentioned
Answer: A
Turbo codes are a class of high-performance forward error correction codes.
9. Components used for the generation of turbo codes are
A. Inter leavers
B. Punching pattern
C. Inter leavers & Punching pattern
D. None of the mentioned
Answer: C
There are many instances of turbo codes, using different component encoders, input/output ratios, inter leavers, and punching patterns.
10. Decoders are connected in series.
A. True
B. False
Answer: A
Two elementary decoders are connected in serial connection for decoding the turbo codes.
