1. Which of the following best describes BCH codes?
A) Linear block codes used for error detection only
B) Non-linear block codes used for error correction only
C) Linear block codes used for error correction
D) Non-linear block codes used for error detection
Answer: C) Linear block codes used for error correction
Explanation: BCH (Bose-Chaudhuri-Hocquenghem) codes are a class of linear block codes primarily utilized for error correction in communication systems.
2. What is the primary purpose of encoding in BCH codes?
A) To increase the efficiency of error detection
B) To compress the data for storage
C) To improve error correction capabilities
D) To ensure secure transmission
Answer: C) To improve error correction capabilities
Explanation: Encoding in BCH codes is essential for introducing redundancy into the transmitted data, enabling more effective error correction at the receiver end.
3. Which technique is commonly used for error location and correction in BCH codes?
A) Hamming distance calculation
B) Syndrome decoding
C) CRC check
D) LRC (Longitudinal Redundancy Check)
Answer: B) Syndrome decoding
Explanation: Syndrome decoding is frequently employed in BCH codes to locate and correct errors by analyzing the syndromes generated during decoding.
4. What is a key characteristic of convolutional codes?
A) They are non-linear block codes
B) They rely solely on parity bits for error correction
C) They exhibit memory in their encoding process
D) They are more efficient for short messages
Answer: C) They exhibit memory in their encoding process
Explanation: Convolutional codes retain memory of previous input symbols, allowing for more sophisticated error correction techniques compared to block codes.
5. Which approach is used in the construction of convolutional encoders?
A) Sequential logic design
B) Randomized algorithm
C) Brute-force method
D) Matrix multiplication
Answer: A) Sequential logic design
Explanation: Convolutional encoders are typically constructed using sequential logic circuits, which process input symbols one at a time and retain memory of previous symbols.
6. In convolutional codes, what does the term “time domain approach” refer to?
A) Encoding process based on linear algebra operations
B) Encoding process using feedback shift registers
C) Representation of codewords as sequences over time
D) Decoding process based on statistical analysis
Answer: C) Representation of codewords as sequences over time
Explanation: The time domain approach in convolutional codes involves representing codewords as sequences of symbols over time, reflecting the sequential nature of encoding and decoding.
7. What is a significant advantage of the transform domain approach in convolutional codes?
A) Improved error detection capabilities
B) Simplified encoding process
C) Resistance to channel noise
D) Efficient storage of encoded data
Answer: B) Simplified encoding process
Explanation: The transform domain approach simplifies the encoding process by converting the convolution operation into a more manageable domain, reducing computational complexity.
8. What does a Code Tree represent in convolutional coding?
A) A graphical representation of all possible codewords
B) A hierarchical structure of encoding rules
C) A method for error correction in noisy channels
D) A technique for encryption in data transmission
Answer: B) A hierarchical structure of encoding rules
Explanation: A Code Tree in convolutional coding depicts the hierarchical structure of encoding rules, illustrating the transitions between different states and symbols in the encoding process.
9. Which concept is represented by a Trellis in convolutional coding?
A) Error correction capability
B) Encoding efficiency
C) Time-domain representation of codewords
D) State transitions during encoding and decoding
Answer: D) State transitions during encoding and decoding
Explanation: A Trellis in convolutional coding visually represents the state transitions that occur during the encoding and decoding processes, aiding in understanding the code’s behavior.
10. What is the primary function of the Viterbi algorithm in convolutional decoding?
A) Error detection
B) Error correction
C) Maximum likelihood decoding
D) Syndrome generation
Answer: C) Maximum likelihood decoding
Explanation: The Viterbi algorithm is used for maximum likelihood decoding in convolutional codes, determining the most likely sequence of transmitted bits based on received signals and the code’s structure.