This set of Digital Communications Multiple Choice Questions & Answers (MCQs) focuses on “Concatenated and interleaving codes and its application in CD”.
1. Compact disc is used for
a) Digital storage
b) Reproduction of audio signals
c) Digital storage & Reproduction of audio signals
d) None of the mentioned
View Answer
Explanation: Compact disc digital audio system is used for both digital storage and reproduction of audio signals.
2. Sources of channel errors are
a) Finger prints
b) Air bubbles
c) Unwanted particles
d) All of the mentioned
View Answer
Explanation: Some of the sources of channel errors are some unwanted particles, air bubbles, finger prints, scratches etc.
3. The CIRC error control scheme includes
a) Correction
b) Concealment
c) Correction & Concealment
d) None of the mentioned
View Answer
Explanation: The cross interleave reed Solomon error control scheme in the CD system involves both correction and concealment of errors.
4. Decoding step consists of
a) De-interleaving
b) Decoding
c) De-interleaving & Decoding
d) None of the mentioned
View Answer
Explanation: The decoder step consists of both De-interleaving and decoding which are performed in the reverse order of encoding steps.
5. The ______ the error correcting capability used, the _____ will be the erasure correcting capability.
a) Larger, smaller
b) Smaller, larger
c) Smaller, smaller
d) Larger, larger
View Answer
Explanation: There is a trade off between error correction and erasure correction, the larger the error correcting capability used the smaller will be the erasure correcting capability.
6. In interpolation
a) New samples are added
b) Unreliable samples are removed
c) New samples are added & Unreliable samples are removed
d) None of the mentioned
View Answer
Explanation: The function of the interpolation function is to add new samples estimated from the reliable ones in place of unreliable ones.
7. The channel that exhibits multi-path fading
a) Has memory
b) Exhibits mutually dependent signal transmission impairments
c) Received signal will be distorted
d) All of the mentioned
View Answer
Explanation: A channel that exhibits multi-path fading where the signal arrives at the receiver over two or more different paths. This channel has memory, exhibits mutually dependent signal transmission impairment.
8. Separating the symbols makes the channel memory-less.
a) True
b) False
View Answer
Explanation: Separating the symbols in time effectively changes a channel with memory into a memory-less one.
9. The minimum end to end delay in block interleaving is
a) 2MN+2M+2
b) 2MN-2M+2
c) 2MN-2M-2
d) 2MN+2M-2
View Answer
Explanation: The inter leaver or De-inter leaver delay is 2MN symbol times. M(N-1)+1 memory cells needs to be filled before transmission can begin. Thus the minimum end to end delay is 2MN-2M+2 symbol times, not including any channel propagation delay.
10. A concatenated code uses
a) One level of coding
b) Two levels of coding
c) Three levels of coding
d) None of the mentioned
View Answer
Explanation: A concatenated code is the one that uses two levels of coding, inner code and outer code to achieve desired error performance.
11. A concatenated code has
a) Low error rate
b) High complexity
c) Low error rate & High complexity
d) None of the mentioned
View Answer
Explanation: A concatenated code has low error rate with an overall implementation complexity which is less than that would be required for single level coding.
12. The performance of non binary concatenated code depends on
a) Bit errors
b) Symbols errors
c) Bit & Symbols errors
d) None of the mentioned
View Answer
Explanation: The performance of non binary code like reed-Solomon code which is also an example for concatenated code depends only on the number of symbol errors in the block.
13. Concatenated code is an example of
a) Error detecting code
b) Error correcting code
c) Error detecting & correcting code
d) None of the mentioned
View Answer
Explanation: Concatenated codes belong to the class of error correcting codes.
14. Turbo code is a
a) Serial concatenation code
b) Parallel concatenation code
c) Block code
d) None of the mentioned
View Answer
Explanation: Turbo codes implemented a parallel concatenation of two convolution codes with an inter leaver and an iterative decoder.
Sanfoundry Global Education & Learning Series – Digital Communications.
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