Domain: Engineering — Communications Engineering
Target concept: FSK Modulator

Video generation prompt: The signal generator outputs a binary digital signal connected to an FSK modulator. The oscilloscope's dual channels display the digital signal and the carrier signal, respectively.

Evaluation guide:
(i) Target concept: Binary digital signal controls instantaneous carrier frequency in real-time via FSK modulation.
Minimum mechanism: Digital input must deterministically select one of two carrier frequencies; frequency switching must be immediate and exclusive (no third frequency, no interpolation); carrier must remain sinusoidal and uninterrupted during each symbol period.
(ii)Storyline: Frame 1–2: Signal generator and FSK modulator shown with active connection (cable visible). Frame 3–4: Oscilloscope enters view with two-channel layout established. Frame 5–7: Channel 2 stabilizes as clean square wave (binary states clearly alternating). Frame 8–10: Channel 1 simultaneously shows carrier waveform switching between two discrete sinusoidal frequencies: each switch occurs at the exact vertical edge of the Channel 2 square wave; no delay, no overlap, no distortion. Perspective: Fixed frontal view encompassing all three devices and full oscilloscope screen; no cutaways, no zooms, no repositioning; all elements fully visible and in focus throughout.

Manual:
Experimental Procedure
1. Connect signal generator output to FSK modulator input.
2. Connect FSK modulator output to oscilloscope Channel 1.
3. Connect signal generator output directly to oscilloscope Channel 2.
4. Power on all devices and set oscilloscope to dual-channel mode.
Observation of Experimental Phenomena
- Channel 2 displays stable binary square wave (two voltage levels, sharp transitions).
- Channel 1 displays sinusoidal carrier whose frequency switches between two fixed values, synchronized with each digital symbol change.
Summary of Experimental Principles
FSK (Frequency Shift Keying) encodes binary data by shifting the carrier frequency between two distinct values — one for logic 0, one for logic 1. The modulator output is a continuous-wave signal whose instantaneous frequency is determined solely by the current digital input state.

Prompt Grounding rubric:
level_1: The signal generator, the FSK modulator, or the oscilloscope is missing from the frame, or the oscilloscope never shows both a digital-looking waveform and a carrier-looking waveform at the same time.
level_2: At least one of the three devices (signal generator, FSK modulator, oscilloscope) is visible, but the oscilloscope does not show both the digital square-wave signal and the carrier signal together (e.g., only one channel is ever active, or the second trace never appears).
level_3: The signal generator, FSK modulator, and oscilloscope are all visible; the oscilloscope shows two separate traces at once, one that looks like a binary square wave and one that looks like a sinusoidal carrier, without either trace crowding out or overlapping the other.
level_4: Everything in Level 3 holds, AND the wiring path is visible and correctly ordered (a cable runs from the signal generator to the FSK modulator's input, and another from the modulator's output to the oscilloscope), with the two channels kept in a clear, non-overlapping layout (e.g., stacked or side by side) so both traces stay individually readable throughout.
level_5: Everything in Level 4 holds, AND the two channels stay in fixed, non-overlapping positions on screen for the whole video: the digital channel shows a clean square wave with flat tops/bottoms and sharp vertical edges, and the carrier channel shows a continuous sine-like waveform that visibly takes on more than one frequency over the course of the video, with no missing cable connections, no channel dropping out, and no on-screen graphical glitches obscuring either trace.

Scientific and Causal Correctness rubric:
level_1: The carrier's frequency does not respond to the digital input at all (e.g., it stays at one constant tone throughout), or the 'digital' trace itself looks smoothly rounded like an analog wave rather than a two-level signal, or both channels show visually identical waveforms.
level_2: One channel reads as a square wave and the other as a sine wave, but the carrier's frequency never changes across the video, or it changes at moments that do not line up with the square wave's transitions (e.g., it drifts or changes at random points).
level_3: The carrier channel clearly shows two distinguishable frequencies (a slower and a faster oscillation), and each frequency change happens close to a square-wave transition; however, some switches noticeably lag or lead the corresponding edge by more than roughly one carrier cycle, or one of the two frequencies is essentially never shown.
level_4: The carrier channel shows exactly two stable frequencies, each one sustained for the full length of one high or low interval of the square wave; frequency switches happen right at the square wave's rising/falling edges with no visible in-between frequency or dropout; the square wave itself keeps flat tops/bottoms and sharp edges throughout.
level_5: The square wave stays strictly two-level with no overshoot or ringing at its edges; the carrier shows only its two intended frequencies with no extra wobble, distortion, or amplitude change; every square-wave transition triggers an immediate, complete switch to the other frequency with no gradual ramp or lingering blend between the two tones, and each frequency is held steady for the entirety of its corresponding symbol.

Spatiotemporal Consistency rubric:
level_1: Devices appear or vanish between frames, the oscilloscope screen flickers or resets partway through, a trace jumps to a different part of the screen instantaneously, or the camera's framing or lighting jumps abruptly with no transition.
level_2: One device blocks another inconsistently from frame to frame, the oscilloscope's grid lines warp or disappear intermittently, a waveform trace blinks or stutters, or a cable shown connecting devices appears to detach and reattach without any visible motion causing it.
level_3: The signal generator, FSK modulator, and oscilloscope keep the same relative positions throughout; the oscilloscope display stays continuously visible with a stable grid and unbroken traces; both waveforms evolve smoothly over time with no sudden jump in position, scale, or baseline, and no visible warping of any device.
level_4: Everything in Level 3 holds, AND every object keeps a consistent size, orientation, and spatial relationship to the others for the whole video; the traces sweep across the screen at a steady, even pace with no jerking or stalling; the grid lines stay evenly spaced and aligned, with no visible shift between the foreground devices and the screen behind them.
level_5: Everything in Level 4 holds, AND the view is completely steady end to end: no visible shaking or trembling of either trace, no change in which device appears to occlude another, no shift in overall brightness, contrast, or color balance, and the camera itself never zooms, pans, or tilts at any point.