Kvadratvåg

Kvadratvåg is the Swedish term for a square wave, a simple periodic waveform that alternates abruptly between two levels, usually represented as -A and +A or 0 and 1. The waveform has a fundamental frequency equal to the reciprocal of its period and contains no even harmonics; its harmonic content consists solely of odd multiples of the fundamental frequency (third, fifth, seventh, etc.). In the Fourier series representation of an ideal square wave, the amplitude of the nth odd harmonic decreases proportionally to 1/n. This harmonic structure gives the square wave its characteristic timbre in audio and its sharp edges in electronic circuits.

The square wave is widely used in digital electronics as a clock signal, because its constant frequency and sharp transitions allow reliable synchronization of digital logic gates. It is also employed in signal processing for modulation techniques, such as pulse-width modulation, and in analog synthesis to produce bright, percussive sounds. In physics, the square wave can be used to study non-linear phenomena and to model periodic forces with sudden changes.

Generating a square wave can be accomplished with various methods. Hardware approaches include using a relaxation oscillator, a Schmitt trigger inverter, or a digital counter with a full‑bridge driver. Software generators create sample sequences via lookup tables or mathematical functions. Practical square waves, however, cannot be ideal; they exhibit finite slew rates and rise/fall times determined by the bandwidth of the generating device, and they suffer from spectral leakage and harmonic distortion when low‑pass filtered. Nonetheless, the square wave remains a fundamental tool in both theoretical analysis and practical applications across engineering, physics, and music.