vähimmäisnäytteenottotaajuus

Vähimmäisnäytteenottotaajuus, often referred to as the Nyquist rate or Nyquist frequency, is a fundamental concept in digital signal processing. It specifies the minimum sampling rate required to accurately reconstruct an analog signal from its discrete samples.

According to the Nyquist-Shannon sampling theorem, to perfectly reconstruct a signal that contains no frequencies higher than f_max, one must sample the signal at a rate (f_s) that is strictly greater than twice the maximum frequency. This means f_s > 2 * f_max. The term 2 * f_max is known as the Nyquist rate.

If a signal is sampled below its Nyquist rate, a phenomenon called aliasing occurs. Aliasing causes higher frequencies in the original analog signal to be misrepresented as lower frequencies in the sampled digital signal. This distortion is irreversible; once aliasing has occurred, it is impossible to recover the original, uncorrupted signal.

Therefore, when digitizing analog signals, it is crucial to select a sampling frequency that is sufficiently high to avoid aliasing. This often involves using anti-aliasing filters before sampling to remove any frequencies above half the desired sampling rate. The concept of vähimmäisnäytteenottotaajuus is vital in various fields, including audio and video recording, telecommunications, and medical imaging, ensuring the integrity and accuracy of digital representations of real-world phenomena.