Error Detection Capability from Minimum Hamming Distance

Error Detection Capability from Minimum Hamming Distance

Verified Sources
Nov 4, 2026

In coding theory, a communication code’s robustness is determined by its minimum distance dmind_{min}. The Hamming distance between two codewords measures how many symbol changes are needed to transform one codeword into the other. This directly governs error detection and error correction.

A standard result is:

  • A code with minimum distance dmind_{min} can detect up to dmin−1d_{min}-1 errors.
  • It can correct up to ⌊dmin−12⌋\left\lfloor \frac{d_{min}-1}{2}\right\rfloor errors.

Therefore, if dmin=5d_{min}=5, the maximum number of errors that can be detected is 5−1=45-1=4.

We match this to the options:

  • (i) 2
  • (ii) 3
  • (iii) 5
  • (iv) 4 ✅

type="tip" title="Detection rule to memorize" content="For error detection, use: maximum detectable errors =dmin−1= d_{min}-1 (because any error pattern with fewer than dmind_{min} flips cannot turn one valid codeword into another)."

type="warning" title="Common confusion" content="Do not use the correction bound for detection. Correction is up to ⌊(dmin−1)/2⌋\left\lfloor (d_{min}-1)/2 \right\rfloor, which would give leftarrow leftarrow different (smaller) numbers for dmin=5d_{min}=5."

Compute Maximum Detectable Errors

  1. 1
    Step 1

    For a code with minimum Hamming distance dmind_{min}, the maximum number of detectable errors is dmin−1d_{min}-1.

  2. 2
    Step 2

    Compute 5−1=45-1=4.

  3. 3
    Step 3

    The correct choice is (iv) 4.

  • minimum distance dmind_{min} sets detection/correction limits.
  • detected error pattern must be distinguishable from all valid codewords.
  • pairwise codeword separation is the reason dmin−1d_{min}-1 is the detection ceiling.

Why detection is $d_{min}-1$

From distance to detection limit

Minimum distance

Step 1

Identify dmind_{min}: smallest Hamming distance between distinct codewords."

Detection capacity

Step 2

Detect up to dmin−1d_{min}-1 errors."

Apply to the problem

Step 3

dmin=5⇒4d_{min}=5 \Rightarrow 4 detectable errors."

Knowledge Check

Question 1 of 3
Q1Single choice

A code has minimum Hamming distance dmin=5d_{min}=5. What is the maximum number of errors it can detect?