what is a filter

author: KZ
Digital filters are one of the circuit components commonly used in televisions today. A digital filter is a device consisting of a digital multiplier, an adder and a delay unit. Its function is to perform arithmetic processing on the digital code of the input discrete signal to achieve the purpose of changing the signal spectrum. Due to the development of electronic computer technology and large-scale integrated circuits, digital filters can be realized by computer software, and can also be realized by large-scale integrated digital hardware in real time. A digital filter is an
Discrete-time system (a specific functional device that converts an input discrete-time signal into a required output discrete-time signal according to a predetermined algorithm). When applying a digital filter to process an analog signal, the input analog signal must first be band-limited, sampled, and converted to analog-to-digital. The sampling rate of the input signal of the digital filter should be greater than twice the bandwidth of the signal to be processed. In order to obtain an analog signal, the output digital signal processed by the digital filter must undergo digital-to-analog conversion and smoothing. Digital filters have the advantages of high precision, high reliability, programmable change characteristics or multiplexing, and easy integration. Digital filters are widely used in speech signal processing, image signal processing, medical biological signal processing and other application fields. Digital filters are of low-pass, high-pass, band-pass, band-stop, and all-pass types. It can be time-invariant or time-varying, causal or acausal, linear or non-linear. The most widely used are linear, time-invariant digital filters.