Error detection — what does parity checking excel at? Select the statement that best describes the capability of parity for detecting transmission errors.
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AParity checking is best suited for detecting single-bit errors in transmitted codes.
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BParity checking is not suitable for detecting single-bit errors in transmitted codes.
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CParity checking is capable of detecting and correcting errors in transmitted codes.
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DParity checking is best suited for detecting double-bit errors that occur during the transmission of codes from one location to another.
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EParity checking reliably detects any even number of erroneous bits.
Answer
Correct Answer: Parity checking is best suited for detecting single-bit errors in transmitted codes.
Explanation
Introduction / Context:Parity bits provide a simple, low-overhead method for error detection in digital communication. They indicate whether the number of 1s in a code word is even or odd, enabling detection of many, but not all, error patterns.
Given Data / Assumptions:
- Single parity bit appended per word
- Either even or odd parity scheme
Concept / Approach:With parity, any single-bit flip toggles the overall parity, making the error detectable. However, two-bit errors restore the original parity in an even-parity scheme, escaping detection. Thus, parity is primarily useful for single-bit error detection, not correction or multi-bit reliability guarantees.
Step-by-Step Reasoning:
Transmit code with parity (even/odd)Single-bit error changes parity ⇒ detectedTwo-bit error maintains parity ⇒ not detectedVerification / Alternative check:Consider a word with even count of 1s using even parity. Flipping two bits keeps the 1-count even. The receiver sees correct parity and accepts the frame, demonstrating the limitation.
Why Other Options Are Wrong:
- Not suitable for single-bit errors: false—this is the core strength of parity.
- Detecting and correcting: parity alone does not correct errors.
- Best for double-bit errors: parity generally misses even-numbered bit flips.
- Detects any even-number errors: incorrect; even-numbered flips are exactly what parity can fail to detect.
Common Pitfalls:
- Overestimating parity as an error-correcting code; it is detection-only and limited.
Final Answer:Parity checking is best suited for detecting single-bit errors in transmitted codes.