Error detection concepts: which description best defines an error-detecting code in data communications?

Difficulty: Easy

Correct Answer: a code in which each expression conforms to specific construction rules so that if certain errors occur, the resulting expression will not conform and the error is detected

Explanation:


Introduction / Context:
Communication systems add redundancy to detect (and sometimes correct) errors introduced by noise, interference, or synchronization problems. Understanding the general definition of an error-detecting code helps categorize specific techniques such as parity, checksums, and cyclic redundancy checks (CRCs).


Given Data / Assumptions:

  • We need a general definition, not a single technique.
  • Examples of techniques include parity (1-bit), checksum (summation), and CRC (polynomial division).
  • One option describes a measurement metric (error rate), not a code.


Concept / Approach:
An error-detecting code imposes structured redundancy so that only a subset of bit patterns are valid. If transmission errors occur, the received pattern will usually violate the structure, enabling detection. This conceptual description is broader than any single method and therefore is the best definition among the choices presented.


Step-by-Step Solution:

Identify the option that defines the principle of error detection rather than one instance or a metric.Note that parity (option b) and checksum (option a) are particular examples, not the general definition.Recognize that option d is the bit/block error rate, not a code.Select the general definition (option c).


Verification / Alternative check:
CRCs, for example, accept only patterns whose polynomial division leaves a specific remainder; any other remainder signals an error, matching the ‘‘rules of construction’’ idea in the correct option.


Why Other Options Are Wrong:

Option a: describes a checksum method, not the general concept.Option b: describes parity, a single-bit error detector.Option d: defines error rate, not an error-detecting code.Option e: incorrect because a correct general definition is provided.


Common Pitfalls:
Treating one technique as the definition; confusing performance metrics with coding methods.


Final Answer:
a code constrained by rules so invalid patterns flag errors (option c).

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