Digital Communication MCQs on “Error Detecting and Correcting Capability and Sampling”.
1. Hamming distance can be given by the number of elements in which
A. They are same
B. They differ
C. Which are non zero
D. None of the mentioned
Answer: B
Clarification: Hamming distance between two code words can be given by the number of elements in which they differ.
2. Code strength is characterized by its
A. Minimum distance
B. Maximum distance
C. Code weight
D. Code size
Answer: A
Clarification: The smallest number of the set given the minimum distance of the code. This minimum distance characterizes the strength of the code.
3. The distance between two code-words is equal to the _____ of the third code-word which is the sum of the first two code-words.
A. Size
B. Weight
C. Minimum distance
D. None of the mentioned
Answer: B
Clarification: The sum of two code words gives a third code which is also a linear code. The distance between two code words is equal to the weight of the third code word.
4. Error detecting capability is given as
A. Dmin + 1
B. Dmin -1
C. Dmin
D. Dmin/2
Answer: B
Clarification: The error detecting capability is given as e = Dmin – 1, where Dmin is the minimum distance of the code word.
5. The minimum distance Dmin can also be given as
A. Dmin >= α + β + 1
B. Dmin <= α + β + 1
C. Dmin >= α + β – 1
D. Dmin <= α + β + 1
Answer: A
Clarification: If a code can correct α errors and detect β errors, then the minimum distance can be given by the relation Dmin >= α + β + 1.
6. The number of errors that can be corrected without erasure information is
A. Dmin+1
B. Dmin – 1
C. (Dmin+1)/2
D. (Dmin – 1)/2
Answer: D
Clarification: If a code has a minimum distance dmin then dmin-1 erasures can be reconstituted. The number of errors that can be corrected without erasure information is (dmin-1)/2.
7. For better efficiency and simplicity, n should be
A. Maximum
B. Minimum
C. Zero
D. Infinity
Answer: B
Clarification: For real world codes, n should be minimum for better efficiency and simplicity.
8. Nyquist frequency is given by
A. fs
B. 2fs
C. fs/2
D. none of the mentioned
Answer: C
Clarification: Nyquist frequency is given as fs/2 where fs is the sampling frequency.
9. Some various types of distortion are
A. Jitter
B. Noise
C. Aperture error
D. All of the mentioned
Answer: D
Clarification: Various types of distortion are aliasing, jitters, aperture error, noise, error due to non linear effects, error due to quantization etc.
10. Noise which can affect sampling are
A. Thermal sensor noise
B. Analog circuit noise
C. Thermal sensor & Analog circuit noise
D. None of the mentioned
Answer: C
Clarification: Some of the noises that can cause distortion in sampling are thermal sensor noise, analog circuit noise etc.
11. Oversampling can completely eliminate
A. Aperture error
B. Non linearity
C. Quantization error
D. All of the mentioned