Build complex waveforms using rotating epicycles (sine components).
What is this illustrating?
This tool illustrates the Fourier Transform, a powerful mathematical technique that allows us to translate a signal between its Time Domain view (how the signal changes over time) and its Frequency Domain view (the specific individual frequencies that make it up). Think of it like taking a complex, mixed audio signal (the time domain) and mathematically separating it into the exact recipe of pure tones (the frequency domain) used to create it.
It demonstrates one of the most fundamental principles of radio electronics and signal processing: Any complex waveform can be constructed by adding together a series of pure sine waves.
The Circles (Epicycles): Each rotating circle represents a single sine wave component.
Amplitude: The radius (size) of the circle represents the amplitude (power/voltage) of that specific frequency.
Frequency: The speed at which the radius line spins represents the frequency. Smaller, faster-spinning circles represent higher frequencies.
Phase: The starting angle of the radius line represents the phase. Shifting the phase changes the physical shape of the final wave without altering its frequency makeup.
Time Domain (Top Display): As the circles spin, their vectors are added together end-to-end. The tip of the final circle traces out the resulting complex signal over time. This represents exactly what you would see if you hooked the signal up to an Oscilloscope.
Frequency Domain (Bottom Display): This bar chart shows the exact "ingredients" of your complex signal. It displays the amplitude of each individual frequency component, representing exactly what you would see if you hooked the signal up to a Spectrum Analyzer.