Skärfrekvens

Skärfrekvens, in Swedish, translates to cutoff frequency in English. It is a fundamental concept in signal processing and electronics, particularly in the design and analysis of filters. A filter is a circuit or algorithm that selectively passes or rejects certain frequencies from a signal. The cutoff frequency defines the boundary between the frequencies that are allowed to pass through the filter (the passband) and those that are attenuated or blocked (the stopband).

For an ideal filter, the cutoff frequency is a sharp transition. However, real-world filters have a more gradual transition. The cutoff frequency is typically defined as the point where the power of the signal is reduced by half, which corresponds to a reduction in amplitude by a factor of the square root of two, or approximately 3 decibels (dB). This 3 dB point is a common convention for defining the cutoff frequency.

Filters are categorized based on their behavior around the cutoff frequency. Low-pass filters allow frequencies below the cutoff frequency to pass and attenuate frequencies above it. High-pass filters do the opposite, allowing frequencies above the cutoff to pass and attenuating those below. Band-pass filters allow a specific range of frequencies to pass, with cutoff frequencies defining the upper and lower limits of this range. Band-stop filters, also known as notch filters, attenuate frequencies within a specific range and allow frequencies outside this range to pass. The skärfrekvens is a critical parameter in determining the performance and application of any filtering system.