Error Detection Capability from Minimum Hamming Distance
In coding theory, a communication code’s robustness is determined by its minimum distance . 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 can detect up to errors.
- It can correct up to errors.
Therefore, if , the maximum number of errors that can be detected is .
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 (because any error pattern with fewer than 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 , which would give different (smaller) numbers for ."
Compute Maximum Detectable Errors
- 1Step 1
For a code with minimum Hamming distance , the maximum number of detectable errors is .
- 2Step 2
Compute .
- 3Step 3
The correct choice is (iv) 4.
Key concepts (with quick links)
- minimum distance sets detection/correction limits.
- detected error pattern must be distinguishable from all valid codewords.
- pairwise codeword separation is the reason is the detection ceiling.
Why detection is $d_{min}-1$
From distance to detection limit
Minimum distance
Step 1Identify : smallest Hamming distance between distinct codewords."
Detection capacity
Step 2Detect up to errors."
Apply to the problem
Step 3detectable errors."
Knowledge Check
A code has minimum Hamming distance . What is the maximum number of errors it can detect?
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I2C Bus Fundamentals: How Many Lines Does I2C Use?
I2C is a two‑wire serial bus that uses SDA (data) and SCL (clock) lines for communication between multiple devices on a board.
- Only two signal lines are required, making I2C a low‑pin‑count solution.
- SDA carries addresses, acknowledgments and data, while SCL provides the timing clock for each bit.
- Both lines are open‑drain/bidirectional with pull‑up resistors, allowing many devices to share the bus safely.
- Communication starts with a START condition, proceeds with address and data transfer, and ends with a STOP condition.