Scenario: Aliasing Surprise - Interview Scenario

Scenario

A sensing pipeline reports unexpected baseband tones only in system tests with real-world blockers. Unit tests with ideal sources show no issue.

OBSERVED METRIC
In-band alias energy exceeds blocker rejection assumptions despite nominal Nyquist placement of the wanted signal.

45-MINUTE INTERVIEW FLOW
0-5: define context and KPI
5-15: classify first failing boundary
15-25: identify proving artifact packet
25-35: propose bounded fix with owner
35-45: define validation matrix and rollback

Common traps to avoid

• Assuming wanted-tone Nyquist compliance prevents alias corruption.

• Relying on digital post-processing to remove folded analog interferers.

• Under-specifying anti-alias filters for realistic blocker and harmonic content.

Scenario debrief

Score response quality on mechanism classification, proving artifact, owner assignment, and rollback-safe mitigation.

assumption -> mechanism -> evidence -> mitigation -> replay

risk reduction trend

Debrief prompts

1. Which boundary failed first and how is it proven?

2. Which analog mechanism best explains the symptom?

3. What bounded fix closes risk with the smallest collateral change?

Key takeaways

• Tie every analog claim to one measurable metric and one proving artifact.

• Prefer minimal reversible mitigations with explicit owner and rollback criteria.

Common pitfalls

• Treating all noise as one scalar instead of path and frequency dependent behavior.

• Changing multiple analog knobs at once and losing causality.

• Declaring closure from nominal behavior without stress replay evidence.