Complex sentence: In electronics and signal processing, a Bessel filter is a type of analog linear filter with a maximally flat group delay (maximally linear phase response), which preserves the wave shape of filtered signals in the passband.
Split into simpler sentences: In electronics and signal processing, a Bessel filter is a type of linear filter with a maximally flat group delay (maximally linear phase response). Analog Bessel filters are characterized by almost constant group delay across the entire passband, thus preserving the wave shape of filtered signals in the passband.