Domain: Engineering — Communications Engineering
Target concept: AM Modulated Signal

Video generation prompt: A set of AM modulated signals is input into a detector for demodulation. The oscilloscope's dual channels separately display the modulated signal and the demodulated baseband signal.

Evaluation guide:
(i) Target concept: Envelope detection of AM signals via passive diode rectifier and RC low-pass filtering.
Minimum mechanism: The detector must perform half-wave rectification followed by capacitive discharge that smooths carrier ripple, leaving only the modulation envelope; oscilloscope dual-channel mode must preserve synchronous timebase to enable direct visual correlation.
(ii)Storyline: [Start] Signal generator outputs AM waveform → [Causal transition] Detector receives AM input and produces rectified + filtered output → [Visibility constraint] Both input (Channel 1) and output (Channel 2) appear simultaneously on oscilloscope screen in fixed side-by-side vertical positions → [Causal transition] Channel 2 waveform must geometrically replicate Channel 1"s envelope shape without carrier remnants → [End] Stable, continuous display confirms functional demodulation. Viewpoint is fixed frontal close-up of oscilloscope screen and immediate front-panel connections; no cutaways, zooms, or off-screen actions.

Manual:
Experimental Procedure
1. Connect AM signal generator output to detector input.
2. Connect detector output to oscilloscope Channel 2 input.
3. Connect AM signal generator output directly to oscilloscope Channel 1 input.
4. Enable dual-channel mode on oscilloscope.
Observation of Experimental Phenomena
- Channel 1 displays high-frequency carrier wave with amplitude varying in sync with modulation signal (envelope shape).
- Channel 2 displays low-frequency waveform matching the envelope shape of Channel 1, with no carrier frequency components.
Summary of Experimental Principles
AM modulation encodes information in the amplitude of a carrier wave. A diode-based envelope detector recovers the original baseband signal by tracing the peaks of the AM waveform — resulting in output identical in shape to the modulation signal.

Prompt Grounding rubric:
level_1: No oscilloscope is shown; or no AM-modulated waveform is shown; or no demodulated baseband waveform is shown; or the display doesn't show two channels at once; none of the required objects (oscilloscope, signal source, detector) appear.
level_2: An oscilloscope is shown but displays only one trace; either the modulated signal or the demodulated signal is shown, not both; the detector or signal source is missing or unidentifiable; the layout does not show two separate channel traces side by side.
level_3: The oscilloscope shows two distinct traces at once, each in its own vertical position on the screen; a detector and a signal source are visible or clearly implied; the two-channel layout is recognizable as a comparison between an input and an output trace.
level_4: Level 3's requirements remain satisfied, and further the two traces are clearly separated vertically with no overlap and are labeled or color-coded as Channel 1 and Channel 2; the detector is visibly wired between the signal source and the oscilloscope input; no extra, unrelated instrument or mislabeled channel appears.
level_5: Level 4's requirements remain satisfied, and further both channel traces stay in the same vertical position on the screen for the entire visible duration; every cable connection from the signal source through the detector to the oscilloscope is visible and physically plausible (e.g., cables run to the correct input jacks); nothing blocks the view of either trace and neither channel's identity is ever ambiguous.

Scientific and Causal Correctness rubric:
level_1: The two traces contradict AM demodulation physics: for example, Channel 2 shows a high-frequency carrier, an inverted envelope, or an unrelated pattern; or Channel 1 shows no amplitude variation at all (a bare, unmodulated carrier); no visible relationship between the two traces exists.
level_2: One trace is physically implausible: Channel 1 lacks visible carrier oscillations inside its envelope, or Channel 2 still shows carrier ripple that is more than about 10% of its own amplitude; the envelope shape of Channel 1 does not match the shape of Channel 2; the peaks of Channel 1's envelope and the peaks of Channel 2 line up at noticeably different points in time.
level_3: Channel 1 shows a high-frequency carrier oscillating inside a smooth upper and lower envelope; Channel 2 shows a low-frequency waveform whose shape matches that envelope; the timing of Channel 1's envelope peaks lines up with Channel 2's peaks; Channel 2 shows no visible high-frequency carrier ripple.
level_4: Level 3's requirements remain satisfied, and further Channel 2 shows no overshoot or ringing where the envelope shape changes; Channel 1's envelope sits symmetrically about the same center line with no visible offset; both traces are drawn on the same horizontal time scale; the polarity of Channel 2 correctly matches the polarity of Channel 1's envelope (no inversion).
level_5: Level 4's requirements remain satisfied, and further Channel 2's waveform closely retains the exact shape of Channel 1's envelope (a rounded envelope produces a rounded Channel 2 waveform, a peaked envelope produces a matching peaked shape), with no visible attenuation, timing lag, or size mismatch between the envelope's height and Channel 2's amplitude; this correspondence holds at every point across the visible trace.

Spatiotemporal Consistency rubric:
level_1: The oscilloscope screen flickers, jumps, or goes blank mid-sequence with no cause; a waveform trace jumps sideways or vertically with no continuous motion; a sudden lighting change hides the traces; the detector or its cables vanish and reappear with no cause; the background changes abruptly.
level_2: One clear break in continuity occurs: a waveform trace restarts or resets mid-display; the grid lines on the screen warp or vanish briefly; a cable connection blinks in and out; one channel's trace appears or disappears with no fade; a shadow or reflection covers more than about 30% of either trace for a stretch of the video.
level_3: Both traces stay visible and stable, with only brief, sub-second flicker allowed at the very start or end of the clip; the oscilloscope's viewing angle stays essentially fixed, with at most a slight shift of a few degrees (well under 5°); neither trace is blocked by anything; every object in the shot (oscilloscope, cables, detector) stays visible and in a sensible spatial arrangement throughout.
level_4: Level 3's requirements remain satisfied, and further the oscilloscope's housing, screen, and control knobs stay in the same position throughout; the traces persist on screen without fading, smearing, or stuttering; the cables stay in the same routing without interruption; no shift in lighting or reflection moves across either trace.
level_5: Level 4's requirements remain satisfied, and further neither trace drifts up, down, left, or right over the course of the video; the grid lines stay evenly spaced and aligned; the oscilloscope's bezel, knobs, and labels stay perfectly still; the cables' bends and connector angles stay the same throughout; the lighting stays even with no moving shadow or change in brightness.