Digital signal processing is a technology that develops in an extremely dynamic way, with new solutions being found all the time. Solutions covering various fields (audio-video, telecommunications, radar technology, etc.) are based on processing analogue electrical signals. Digital technology used to process them enables realizing very complex algorithms, speeds-up product development time and assures flexibility of device structure. In many cases, hardware complexity, costs and energy consumption of digital solution are far lower and reliability and resistance to interference are higher compared to classical (analogue) solution. Digital processing may be employed for signals of fraction of Hz to hundreds MHz. For signals with complex spectrum (radiolocation, mobile telephony), very low dynamics (high noise level) or very low frequency (fractions of Hz) digital solutions are often the only acceptable ones.