Anti-aliasing filterMathematical transformation reducing the damage caused by aliasing An anti-aliasing filter (AAF) is a filter used before a signal sampler to restrict the bandwidth of a signal to satisfy the Nyquist–Shannon sampling theorem over the band of interest. Since the theorem states that unambiguous reconstruction of the signal from its samples is possible when the power of frequencies above the Nyquist frequency is zero, a brick wall filter is an idealized but impractical AAF.
AliasingIn digital signal processing, aliasing is a phenomenon in which a reconstructed signal from samples of the original signal contains low frequency components that are not present in the original one. This is caused when, in the original signal, there are components at frequency exceeding a certain frequency called Nyquist frequency, fs/2{\textstyle f_{\text{s}}/2}, where fs{\textstyle f_{\text{s}}} is the sampling frequency (undersampling).
Electronic filterElectronic filters are a type of signal processing filter in the form of electrical circuits. This article covers those filters consisting of lumped electronic components, as opposed to distributed-element filters. That is, using components and interconnections that, in analysis, can be considered to exist at a single point. These components can be in discrete packages or part of an integrated circuit.
Nyquist frequencyIn signal processing, the Nyquist frequency (or folding frequency) is a characteristic of a sampler, which converts a continuous function or signal into a discrete sequence. It is named after Harry Nyquist. For a given sampling rate (samples per second), the Nyquist frequency (cycles per second) is the frequency whose cycle-length (or period) is twice the interval between samples, thus 0.5 cycles/sample. For example, audio CDs have a sampling rate of 44,100 samples/second.
Sinc functionIn mathematics, physics and engineering, the sinc function (), denoted by sinc(x), is defined as either sinc(x)=sinxx{\displaystyle \operatorname {sinc} (x)={\frac {\sin x}{x}}} or sinc(x)=sinπxπx,{\displaystyle \operatorname {sinc} (x)={\frac {\sin \pi x}{\pi x}},}the latter of which is sometimes referred to as the normalized sinc function.
Analog-to-digital converterIn electronics, an analog-to-digital converter (ADC, A/D, or A-to-D) is a system that converts an analog signal, such as from fingers touching a touchscreen, sound entering a microphone, or light entering a digital camera, into a digital signal. An ADC may also provide an isolated measurement, such as an electronic device that converts an analog input voltage or current to a digital number representing the magnitude of the voltage or current.
Digital-to-analog converterDevice that converts a digital signal into an analog signal 8-channel Cirrus Logic CS4382 digital-to-analog converter as used in a sound card. In electronics, a digital-to-analog converter (DAC, D/A, D2A, or D-to-A) is a system that converts a digital signal into an analog signal. An analog-to-digital converter (ADC) performs the reverse function. DACs are commonly used in music players to convert digital data streams into analog audio signals.
Digital signal (signal processing)In the context of digital signal processing (DSP), a digital signal is a discrete time, quantized amplitudesignal. In other words, it is a sampled signal consisting of samples that take on values from a discrete set (a countable set that can be mapped one-to-one to a subset of integers). If that discrete set is finite, the discrete values can be represented with digital words of a finite width.
Analog signalAn analog signal (American English) or analogue signal (British and Commonwealth English) is any signal, typically a continuous-time signal, representing some other quantity, i.e., analogous to another quantity. For example, in an analog audiosignal, the instantaneous signal voltage varies in a manner analogous to the pressure of the sound waves.
Medical imagingMedical imaging is the technique and process of imaging the interior of a body for clinical analysis and medical intervention, as well as visual representation of the function of some organs or tissues (physiology). Medical imaging seeks to reveal internal structures hidden by the skin and bones, as well as to diagnose and treat disease. Medical imaging also establishes a database of normal anatomy and physiology to make it possible to identify abnormalities.
Nyquist–Shannon sampling theoremExample of magnitude of the Fourier transform of a bandlimited functionThe Nyquist–Shannon sampling theorem, or the sampling theorem, is a theorem in the field of signal processing which serves as a fundamental bridge between continuous-time signals and discrete-time signals.BandlimitingLimiting a signal to contain only low-frequency components Bandlimiting is the process of reducing a signal’s energy outside a specific frequency range, keeping only the desired part of the signal’s spectrum. This technique is crucial in signal processing and communications to ensure signals stay clear and effective.*As an Amazon Associate I earn from qualifying purchases.