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

Video generation prompt: A set of FM modulated signals is input into a frequency discriminator for demodulation, with the original FM carrier signal displayed on one channel of the oscilloscope and the discriminator's output displayed on the other channel.

Evaluation guide:
(i) Target concept: Visual verification of FM demodulation functionality through synchronous dual-channel oscilloscope observation.
Minimum mechanism: Frequency discriminator must be actively converting frequency variations of an FM carrier into a voltage signal proportional to the original modulating waveform; oscilloscope must render both the discriminator input-equivalent (carrier) and output (baseband) as stable, concurrent, spatially separated waveforms with causally linked dynamics.
(ii)Storyline: [Frame 0–2] FM signal generator and frequency discriminator shown connected by coaxial cable; [Frame 3–5] Oscilloscope powered on, dual-channel mode engaged, upper/lower channels illuminated; [Frame 6–10] Stable waveforms appear: upper channel displays low-frequency sinusoid (baseband), lower channel displays high-frequency carrier with synchronous frequency modulation, all within fixed viewpoint, no camera motion, no occlusion, no UI interruption.

Manual:
Experimental Procedure
1. Connect FM signal generator output to frequency discriminator input.
2. Connect frequency discriminator output to oscilloscope input channel.
3. Enable dual-channel display: feed the original FM carrier signal to the lower channel and the frequency discriminator's output to the upper channel.
Observation of Experimental Phenomena
Upper channel shows smooth low-frequency baseband waveform; lower channel shows high-frequency FM carrier waveform with visible frequency variation — two distinct, simultaneous, side-by-side waveforms.
Summary of Experimental Principles
FM demodulation via frequency discriminator converts instantaneous carrier frequency deviations into proportional output voltage, recovering the original baseband signal. The oscilloscope dual-channel display enables direct visual comparison of input (carrier) and output (baseband).

Prompt Grounding rubric:
level_1: No FM signal source, frequency discriminator, or oscilloscope appears in frame; or the oscilloscope screen is not shown; or only one channel trace is visible instead of two.
level_2: The signal source, discriminator, and oscilloscope are present but not connected to each other in a continuous cable path; or the oscilloscope shows only one active channel while the second stays blank; or no waveform of any kind is visible on the screen.
level_3: The FM signal source is cabled to the discriminator input, the discriminator output is cabled to the oscilloscope input, and the oscilloscope screen shows two simultaneously active channel traces (upper and lower); both traces are moving/non-flat, but they look identical in shape and amplitude to each other.
level_4: In addition to level 3, the cabling path (source to discriminator to oscilloscope) is unbroken and visible, the two channel traces are clearly distinguishable from one another in shape (not just amplitude-scaled copies of the same trace), and no cable or connector detaches or vanishes mid-recording.
level_5: In addition to level 4, the two channel traces stay simultaneously visible side by side for the full recording with a stable vertical separation between them, no on-screen menu, label, or overlay ever covers either trace, and the equipment (source, discriminator, oscilloscope) keeps a fixed physical layout with no camera pan or cut.

Scientific and Causal Correctness rubric:
level_1: The two channels violate basic FM demodulation physics: e.g., both channels are flat lines, both display the same high-frequency carrier, or the low-frequency baseband trace and the high-frequency carrier trace are swapped onto the wrong channels relative to what the discriminator should output.
level_2: The discriminator appears connected but its output channel shows only a flat DC line, random noise, or an unrelated waveform shape (e.g., a square wave or staircase) with no visible relationship to a carrier being converted into a baseband signal.
level_3: One channel shows a slow, smooth periodic waveform and the other shows a fast periodic waveform, and both are continuous and clearly non-flat, but the two traces do not appear linked to each other (e.g., the slow trace's rise-and-fall pattern does not visibly track any change in the fast trace's density).
level_4: The slow channel shows a clean, smooth low-frequency waveform with roughly 1-5 visible cycles, and the fast channel shows a carrier-like trace whose cycles visibly bunch closer together and spread further apart over time, but the timing of these bunching/spreading changes does not clearly line up with the rises and falls of the slow trace.
level_5: The slow-channel waveform is clean and smooth, and the fast-channel carrier trace visibly speeds up (cycles packed tighter) whenever the slow trace is rising toward a peak and visibly slows down (cycles spread wider) whenever the slow trace is falling toward a trough, so a viewer can see, without measurement, that the carrier's apparent speed is being driven by the baseband waveform, consistent with frequency-to-voltage conversion.

Spatiotemporal Consistency rubric:
level_1: The oscilloscope, discriminator, or cables abruptly vanish or appear mid-recording; a channel trace jumps sideways or vertically to a new position with no motion in between; the room lighting suddenly jumps between very dark and very bright; the discriminator's case visibly flickers or breaks apart.
level_2: The oscilloscope screen shows visible tearing or restart artifacts; a trace restarts from the left edge of the screen without a continuous sweep; a cable connecting the discriminator to the oscilloscope disconnects and reconnects with no hand or tool visibly doing it; the upper/lower channel labels blink on and off; the room lighting pulses noticeably.
level_3: The source, discriminator, and oscilloscope all stay in place and visible throughout; both channel traces are unbroken and continuously drawn; there is no teleportation, warping, or sudden occlusion of any object, but the channel-divider line or trace baseline shows a small, visible wobble that never causes a viewer to lose track of which trace is which.
level_4: In addition to level 3, no equipment vanishes, warps, or is occluded at any point, both channel traces stay unbroken for the entire recording, and any baseline drift on either trace stays under roughly 10% of the trace's vertical scale, small enough that it never visibly changes the shape or identity of the waveform.
level_5: In addition to level 4, the equipment stays perfectly still in frame with no visible drift or wobble, the channel-divider line stays sharp and steady, both waveform traces are smooth and continuous with no visible flicker, stutter, or jump, and the room lighting stays even with no visible flash, shadow change, or brightness drift for the whole recording.