Analyze a digital communication chain

Supplied materials

• All measurements and observations below are supplied classroom examples. They are not data from actual learners or a claim about a particular real site.
• Paper or a browser document for a labeled drawing, table or explanation.
• Worked problem inputs: Receiver detects a checksum mismatch but has no recovery protocol. Explain what is and is not accomplished.
• Assessment case 1: The agreed code maps HELP to 0101; noise changes the received bits to 0111. What follows before decoding? Which inference or prediction is best supported?
• Assessment case 2: Which scientific label fits the specifically described step or feature? Supplied case: Send pulses along a modeled channel.
• Assessment case 3: Which scientific label fits the specifically described step or feature? Supplied case: Convert received bits into a word.
• Assessment case 4: Which scientific label fits the specifically described step or feature? Supplied case: Compare a supplied checksum.
• Assessment case 5: Which scientific label fits the specifically described step or feature? Supplied case: Assign numbers to signal patterns.
• Assessment case 6: A receiver uses a different code table than the sender, even with unchanged bits. What is predicted? Which inference or prediction is best supported?

Learn the idea

Encoding assigns data to signals, transmission carries them, decoding recovers data and checking tests integrity. A detected error is not automatically corrected; the protocol must specify a response.

Encode means map information into signal symbols. Transmit means send the signal through a channel. Decode means map received symbols back to information. Check means compare received data with an integrity rule.

For the supplied mechanism problem, Receiver detects a checksum mismatch but has no recovery protocol. Explain what is and is not accomplished. The check provides evidence of inconsistency but does not automatically repair the message. Correction, retry or rejection requires a separately specified protocol.

1. Read the supplied problem and mark the structures, processes or quantities named: Receiver detects a checksum mismatch but has no recovery protocol. Explain what is and is not accomplished.
2. Draw the relevant boundary, pathway or comparison and label it using the scientific ideas above.
3. Write a causal explanation or calculation, showing how each observation supports the result.
4. Compare your reasoning with the worked solution; name a condition that would change or limit the inference.

Check your reasoning

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Take it further

New protocol case: a failed check triggers a specified retry. Expected: distinguish detecting the inconsistency from the retry action; only the protocol supplies the recovery response.

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