Vähimmäisnäytteenottotaajuus

Vähimmäisnäytteenottotaajuus, also known as the Nyquist frequency or Nyquist rate, is a fundamental concept in digital signal processing. It refers to the minimum sampling rate required to accurately reconstruct an analog signal from its discrete samples. According to the Nyquist-Shannon sampling theorem, this minimum rate is twice the highest frequency present in the analog signal.

If a signal is sampled at a rate lower than its vähimmäisnäytteenottotaajuus, a phenomenon called aliasing occurs. Aliasing distorts the sampled signal, causing higher frequencies to be misrepresented as lower frequencies. This can lead to significant inaccuracies and errors in the reconstructed analog signal.

To avoid aliasing, the sampling frequency must be strictly greater than twice the maximum frequency component of the signal. In practice, an anti-aliasing filter is often used before sampling to remove or attenuate frequencies above half the sampling rate, ensuring that the Nyquist criterion is met. The vähimmäisnäytteenottotaajuus is crucial for applications such as digital audio, digital image processing, and telecommunications, where the accurate conversion of analog signals to digital and back is essential.