vähimmäisnäytteenottotaajuuden

Vähimmäisnäytteenottotaajuus, often referred to by its English equivalent Nyquist-Shannon sampling theorem, is a fundamental concept in digital signal processing. It states that to perfectly reconstruct an analog signal from its discrete samples, the sampling frequency must be at least twice the highest frequency component present in the signal. This minimum sampling frequency 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 misinterpreted as lower frequencies in the sampled digital signal. This distortion is irreversible; once aliasing has happened, the original high-frequency components cannot be recovered.

The Nyquist-Shannon sampling theorem is crucial for many applications, including digital audio, digital photography, telecommunications, and medical imaging. For example, in audio recording, human hearing typically extends up to about 20 kHz. Therefore, to avoid aliasing and capture the full range of audible frequencies, audio signals are sampled at a minimum of 40 kHz, with common rates like 44.1 kHz (used for CDs) or 48 kHz being employed. Understanding and applying the vähimmäisnäytteenottotaajuus ensures the integrity and accuracy of digital representations of analog information.