Keräystaajuus

Keräystaajuus, often translated as sampling rate or sampling frequency, is a fundamental concept in digital signal processing. It refers to the number of samples of an analog signal taken per unit of time. In simpler terms, it's how often a digital system measures the value of a continuous signal to convert it into a discrete representation.

The unit of keräystaajuus is Hertz (Hz), meaning cycles per second. For example, a keräystaajuus of 44.1 kHz means that the analog signal is measured 44,100 times every second. A higher keräystaajuus generally allows for a more accurate digital representation of the original analog signal, capturing more detail and nuances.

The Nyquist-Shannon sampling theorem is closely related to keräystaajuus. It states that to perfectly reconstruct an analog signal from its samples, the keräystaajuus must be at least twice the highest frequency component present in the signal. This minimum rate is known as the Nyquist rate. If the keräystaajuus is too low, aliasing can occur, where higher frequencies are incorrectly represented as lower frequencies, leading to distortion.

Keräystaajuus is crucial in various applications, including digital audio, digital imaging, telecommunications, and sensor data acquisition. In audio, standard keräystaajuudet like 44.1 kHz (for CDs) and 48 kHz (for digital video) are common. In imaging, the resolution is related to the spatial sampling rate. Choosing the appropriate keräystaajuus is a balance between accuracy, data storage, and processing power requirements.