The sampling frequency or sampling rate defines the number of samples per second taken from a continuous signal to make a discrete signal. It is measured in hertz (Hz). The inverse of the sampling frequency is the sampling period or sampling time, which is the time between samples. A sample refers to a value or set of values at a point in time and/or space. ... Look up second in Wiktionary, the free dictionary. ... A continuous signal or a continuous time signal is a varying quantity (a signal) that can be, or is expressed, as a continuous function of an independent variable, usually time. ... A discrete signal is a signal that has been sampled from a continuous signal. ... The hertz (symbol: Hz) is the SI unit of frequency. ... A sample refers to a value or set of values at a point in time and/or space. ...

The sampling frequency can only be applied to samplers in which each sample is periodically taken. There is no rule that limits a sampler from taking a sample at a non-periodic rate. A sampler can be any of the following things: In general, a sampler is any broadly representative cross-section of some collection; for instance, food products are sometimes packaged in samplers containing a variety of chocolates or beers. ...

The common notation for sampling frequency is f_s which stands for frequency (subscript) sampled.

Sampling theorem

The Nyquist-Shannon sampling theorem states that the sampling frequency has to be greater than twice the bandwidth of the signal being sampled, or equivalently that the Nyquist frequency must exceed the bandwidth of the signal being sampled. The Nyquist-Shannon sampling theorem is the fundamental theorem in the field of information theory, in particular telecommunications. ... Bandwidth is a measure of frequency range, measured in hertz, of a function of a frequency variable. ... The Nyquist frequency, named after the Nyquist-Shannon sampling theorem, is half the sampling frequency for a signal. ...

If a signal has a bandwidth of 100 Hz then to avoid aliasing the sampling frequency must be greater than 200 Hz. On statistics, signal processing, and related disciplines, aliasing is an effect that causes different continuous signals to become indistinguishable (or aliases of one another) when sampled. ...

In other words, the sampling frequency must be at least twice the maximum frequency component of the signal. Otherwise, the original signal cannot be recovered from the sampled signal.

Oversampling

In some cases, it is desirable to have a sampling frequency more than twice the bandwidth so that a digital filter can be used in exchange for a weaker analog anti-aliasing filter. This process is known as oversampling. An FIR filter In electronics, a digital filter is any electronic filter that works by performing digital math operations on an intermediate form of a signal. ... An anti-aliasing filter is commonly used in conjuction with digital signal processing and is a filter to restrict the bandwidth to approximately satisfy the Shannon-Nyquist sampling theorem. ... In signal processing, oversampling is the process of sampling a signal with a sampling frequency significantly higher than twice the bandwidth or highest frequency of the signal being sampled. ...

Audio

In digital audio, common sampling rates are: To meet Wikipedias quality standards, this article or section may require cleanup. ...

• 8,000 Hz - telephone, adequate for human speech
• 11,025 Hz
• 22,050 Hz - radio
• 32,000 Hz - miniDV digital video camcorder, DAT (LP mode)
• 44,100 Hz - audio CD, also most commonly used with MPEG-1 audio (VCD, SVCD, MP3)
• 47,250 Hz - world's first commercial PCM sound recorder by Nippon Columbia (Denon)
• 48,000 Hz - digital sound used for digital TV, DVD, DAT, films and professional audio
• 50,000 Hz - first commercial digital audio recorders from the late 70's from 3M and Soundstream
• 50,400 Hz - sampling rate used by the Mitsubishi X-80 digital audio recorder
• 96,000 or 192,400 Hz - DVD-Audio, some LPCM DVD tracks, BD-ROM (Blu-ray Disc) audio tracks, and HD-DVD (High-Definition DVD) audio tracks
• 2.8224 MHz - SACD, 1-bit sigma-delta modulation process known as Direct Stream Digital, co-developed by Sony and Philips

The telephone or phone (Greek: tele = far away and phone = voice) is a telecommunications device which is used to transmit and receive sound (most commonly voice and speech) across distance. ... A MiniDV tape Digital Video (DV) is a video format launched in 1996, and, in its smaller tape form factor MiniDV, has since become one of the standards for consumer and semiprofessional video production. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... The Compact Disc logo was inspired by that of the previous Compact Cassette. ... MPEG-1 is the designation for a group of audio and video coding standards agreed upon by MPEG (Moving Picture Experts Group). ... VCD can stand for: Video CD Voice command device Value Change Dump (IEEE 1364 Verilog) Value-Centered Design This page concerning a three-letter acronym or abbreviation is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. ... Super Video Compact Disc (SVCD) is a format used for storing video on standard compact discs or CD-Rs. ... MPEG-1 Audio Layer 3, more commonly referred to as MP3, is a popular digital audio encoding and lossy compression format, designed to greatly reduce the amount of data required to represent audio, yet still sound like a faithful reproduction of the original uncompressed audio to most listeners. ... PCM is an initialism which can have different meanings: Phase Change Material Pulse-code modulation, a way to digitally encode signals representing sound and their video counterparts Potential Cancer Marker Communist Party of Mexico Plug Compatible Manufacturer Power-train control module, a computer in a car which controls the car... Digital television (DTV) uses digital modulation and compression to broadcast video, audio and data signals to television sets. ... DVD (also known as Digital Versatile Disc or Digital Video Disc) is an optical disc storage media format that can be used for data storage, including movies with high video and sound quality. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... 3M Company (NYSE: MMM); formerly Minnesota Mining and Manufacturing Company until 2002) is an American corporation with a worldwide presence that produces over 55,000 products, including adhesives, abrasives, laminates, passive fire protection, electronic circuits and displays, and pharmaceuticals. ... Soundstream Inc. ... Mitsubishi Logo The Mitsubishi Group ), Mitsubishi Group of Companies, or Mitsubishi Companies, all refer to a large grouping of independently operated Japanese companies which share the Mitsubishi brand name. ... The DVD-Audio logo. ... Linear Pulse Code Modulation (LPCM) is a format that is a popular choice in the Music Production. ... ... HD DVD (High Density Digital Versatile Disc or High Definition Digital Video Disc) is a digital optical media format which can hold high definition video or other data. ... Super Audio CD (SACD) is a new audio recording format aimed at providing higher fidelity audio reproduction than the compact disc. ... In information theory, oversampling is the process of sampling a signal with a sampling frequency higher than the nyquist frequency. ... Direct-Stream Digital (DSD) is an encoding technology to store audio signals on digital storage media and is used for the super audio compact disc (SACD). ... Sony Corporation ) is one of the worlds largest media conglomerates founded in Tokyo, Japan. ... Koninklijke Philips Electronics N.V. (Royal Philips Electronics N.V.), usually known as Philips, (Euronext: PHIA, NYSE: PHG) is one of the largest electronics companies in the world. ...

Video systems

In digital video, the sampling rate is defined the frame/field rate, rather than the notional pixel clock. The image sampling frequency is the repetition rate of the sensor integration period. Since the integration period may be significantly shorter than the time between repetitions, the sampling frequency can be different from the inverse of the sample time. Digital video is a type of video recording system that works by using a digital, rather than analog, representation of the video signal. ...

• 50 Hz - PAL video
• 60 / 1.001 Hz - NTSC video

When analogue video is converted to digital video, a different sampling process occurs, this time at the pixel frequency. Some common pixel sampling rates are: PAL, short for phase-alternating line, phase alternation by line or phase alternation line, is a colour encoding system used in broadcast television systems in large parts of the world. ... NTSC is the analog television system in use in Korea, Japan, United States, Canada and certain other places, mostly in the Americas (see map). ... Digital video is a type of video recording system that works by using a digital, rather than analog, representation of the video signal. ... This example shows an image with a portion greatly enlarged. ...

• 13.5 MHz - CCIR 601, D1 video

Aliasing of high-frequency luminance components shows up as a moiré pattern. CCIR 601 is the old name of a standard published by the CCIR (now ITU-R) for encoding interlaced analogue video signals in digital form. ... On statistics, signal processing, and related disciplines, aliasing is an effect that causes different continuous signals to become indistinguishable (or aliases of one another) when sampled. ... As applied to analog television signals, two different words are used, luminance and luma, meaning two different things. ... A moiré pattern is an interference pattern created, for example, when two grids are overlaid at an angle, or when they have slightly different mesh sizes. ...

See also

• Continuous signal vs. Discrete signal
• MP3
• Digital control
• Sample and hold
• Sample (signal)
• Sampling (signal processing)
• Signal (information theory)

A continuous signal or a continuous time signal is a varying quantity (a signal) that can be, or is expressed, as a continuous function of an independent variable, usually time. ... A discrete signal is a signal that has been sampled from a continuous signal. ... MPEG-1 Audio Layer 3, more commonly referred to as MP3, is a popular digital audio encoding and lossy compression format, designed to greatly reduce the amount of data required to represent audio, yet still sound like a faithful reproduction of the original uncompressed audio to most listeners. ... Digital control is a branch of control theory that uses digital computers to act as a system. ... In electronics, a sample and hold circuit is used to interface real-world, changing analogue signals to a subsequent system such as an analog-to-digital converter. ... A sample refers to a value or set of values at a point in time and/or space. ... In signal processing, sampling is the reduction of a signal (information theory) from continuous time to discrete time. ... In information theory, a signal is the sequence of states of a communications channel that encodes a message. ...

External link

• Why exactly 44.1 kHz?