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ETP-1 Recreation
ETP-1 (or Electronic Test Pattern One) was a test card designed and used by the Independent Broadcasting Authority (IBA). After test transmissions from the IBA's Engineering Regional Operations Centre (ROC) in Croydon from 1978 it was phased in on ITV over a period starting from 1979, replacing, in different ITV regions: Test Card F, Test Card G and full screen height EBU colour bars. After ITV went 24 hours in 1988, the card ceased to be seen on the channel. It was used for both 625-line PAL and 405-line monochrome broadcasts. It was also seen extensively on both Channel 4 and S4C during both their pre-launch tests and their downtime of those channels, due to their limited hours early on. After launch, it was alternated with in-vision teletext services from ORACLE and 4-Tel on View/ Sbectel. On these channels, it was captioned either IBA:CH4 or IBA:S4C, with lines above and below this indicating the card was being generated by the channel, the absence of these lines meant ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ETP-1 Recreation
ETP-1 (or Electronic Test Pattern One) was a test card designed and used by the Independent Broadcasting Authority (IBA). After test transmissions from the IBA's Engineering Regional Operations Centre (ROC) in Croydon from 1978 it was phased in on ITV over a period starting from 1979, replacing, in different ITV regions: Test Card F, Test Card G and full screen height EBU colour bars. After ITV went 24 hours in 1988, the card ceased to be seen on the channel. It was used for both 625-line PAL and 405-line monochrome broadcasts. It was also seen extensively on both Channel 4 and S4C during both their pre-launch tests and their downtime of those channels, due to their limited hours early on. After launch, it was alternated with in-vision teletext services from ORACLE and 4-Tel on View/ Sbectel. On these channels, it was captioned either IBA:CH4 or IBA:S4C, with lines above and below this indicating the card was being generated by the channel, the absence of these lines meant ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shopping Channel
Shopping channels (also known in British English as teleshopping) are a type of television program or specialty channel devoted to home shopping. Their formats typically feature live presentations and demonstrations of products, hosted by on-air presenters and other spokespeople who provide a sales pitch for the product. Viewers are also instructed on how they can order the product. Shopping channels may focus primarily on mainstream merchandise, or more specialized categories such as high-end fashion and jewelry. The term can also apply to channels whose programming consists exclusively of direct-response advertising and infomercials. The concept was first popularized in the United States in the 1980s, when Lowell "Bud" Paxson and Roy Speer launched a local cable channel known as the Home Shopping Club—which later launched nationally as the Home Shopping Network (HSN). It later gained competition from QVC, who would eventually acquire HSN in 2017. Home shopping channels origina ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sine Wave
A sine wave, sinusoidal wave, or just sinusoid is a curve, mathematical curve defined in terms of the ''sine'' trigonometric function, of which it is the graph of a function, graph. It is a type of continuous wave and also a Smoothness, smooth periodic function. It occurs often in mathematics, as well as in physics, engineering, signal processing and many other fields. Formulation Its most basic form as a function of time (''t'') is: y(t) = A\sin(2 \pi f t + \varphi) = A\sin(\omega t + \varphi) where: * ''A'', ''amplitude'', the peak deviation of the function from zero. * ''f'', ''frequency, ordinary frequency'', the ''Real number, number'' of oscillations (cycles) that occur each second of time. * ''ω'' = 2''f'', ''angular frequency'', the rate of change of the function argument in units of radians per second. * \varphi, ''phase (waves), phase'', specifies (in radians) where in its cycle the oscillation is at ''t'' = 0. When \varphi is non-zero, the entire waveform appears to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Integral Linearity
A measurement system consists of a sensor, to input the physical parameter that is of interest, and an output to a medium that is suitable for reading by the system that needs to know the value of the parameter. (This could be a device to convert the temperature of the surrounding air or water into the visually readable height of a column of mercury in a small tube, for example; but the conversion could also be made to an electronic encoding of the parameter, for reading by a computer system.) The integral linearity is then a measure of the fidelity of the conversion that is performed by the measuring system. It is the relation of the output to the input over a range expressed as a percentage of the full-scale measurements. Integral linearity is a measure of the device's deviation from ideal linear behaviour. The most common denotation of integral linearity is independent linearity. In the context of a digital-to-analog converter (DAC) or an analog-to-digital converter ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Greyscale
In digital photography, computer-generated imagery, and colorimetry, a grayscale image is one in which the value of each pixel is a single sample representing only an ''amount'' of light; that is, it carries only intensity information. Grayscale images, a kind of black-and-white or gray monochrome, are composed exclusively of shades of gray. The contrast ranges from black at the weakest intensity to white at the strongest. Grayscale images are distinct from one-bit bi-tonal black-and-white images, which, in the context of computer imaging, are images with only two colors: black and white (also called ''bilevel'' or '' binary images''). Grayscale images have many shades of gray in between. Grayscale images can be the result of measuring the intensity of light at each pixel according to a particular weighted combination of frequencies (or wavelengths), and in such cases they are monochromatic proper when only a single frequency (in practice, a narrow band of frequencies) is ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Colorfulness
Colorfulness, chroma and saturation are attributes of perceived color relating to chromatic intensity. As defined formally by the International Commission on Illumination (CIE) they respectively describe three different aspects of chromatic intensity, but the terms are often used loosely and interchangeably in contexts where these aspects are not clearly distinguished. The precise meanings of the terms vary by what other functions they are dependent on. * Colorfulness is the "attribute of a visual perception according to which the perceived color of an area appears to be more or less chromatic"., page 87. The colorfulness evoked by an object depends not only on its spectral reflectance but also on the strength of the illumination, and increases with the latter unless the brightness is very high ( Hunt effect). * Chroma is the "colorfulness of an area judged as a proportion of the brightness of a similarly illuminated area that appears white or highly transmitting". As a resu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amplitude
The amplitude of a periodic variable is a measure of its change in a single period (such as time or spatial period). The amplitude of a non-periodic signal is its magnitude compared with a reference value. There are various definitions of amplitude (see below), which are all functions of the magnitude of the differences between the variable's extreme values. In older texts, the phase of a periodic function is sometimes called the amplitude. Definitions Peak amplitude & semi-amplitude For symmetric periodic waves, like sine waves, square waves or triangle waves ''peak amplitude'' and ''semi amplitude'' are the same. Peak amplitude In audio system measurements, telecommunications and others where the measurand is a signal that swings above and below a reference value but is not sinusoidal, peak amplitude is often used. If the reference is zero, this is the maximum absolute value of the signal; if the reference is a mean value (DC component), the peak amplitude is the maximu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cathode-ray Tube
A cathode-ray tube (CRT) is a vacuum tube containing one or more electron guns, which emit electron beams that are manipulated to display images on a phosphorescent screen. The images may represent electrical waveforms (oscilloscope), pictures (television set, computer monitor), radar targets, or other phenomena. A CRT on a television set is commonly called a picture tube. CRTs have also been used as memory devices, in which case the screen is not intended to be visible to an observer. The term ''cathode ray'' was used to describe electron beams when they were first discovered, before it was understood that what was emitted from the cathode was a beam of electrons. In CRT television sets and computer monitors, the entire front area of the tube is scanned repeatedly and systematically in a fixed pattern called a raster. In color devices, an image is produced by controlling the intensity of each of three electron beams, one for each additive primary color (red, green, and blue ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cathode-ray Tube
A cathode-ray tube (CRT) is a vacuum tube containing one or more electron guns, which emit electron beams that are manipulated to display images on a phosphorescent screen. The images may represent electrical waveforms (oscilloscope), pictures (television set, computer monitor), radar targets, or other phenomena. A CRT on a television set is commonly called a picture tube. CRTs have also been used as memory devices, in which case the screen is not intended to be visible to an observer. The term ''cathode ray'' was used to describe electron beams when they were first discovered, before it was understood that what was emitted from the cathode was a beam of electrons. In CRT television sets and computer monitors, the entire front area of the tube is scanned repeatedly and systematically in a fixed pattern called a raster. In color devices, an image is produced by controlling the intensity of each of three electron beams, one for each additive primary color (red, green, and blue ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crystal Palace Transmitting Station
The Crystal Palace transmitting station, officially known as Arqiva Crystal Palace, is a broadcasting and telecommunications site in the Crystal Palace area of the London Borough of Bromley, England (). It is located on the site of the former television station and transmitter operated by John Logie Baird from 1933. The station is the eighth-tallest structure in London, and is best known as the main television transmitter for the London area. As such, it is the most important transmitter in the UK in terms of population covered. The transmitter is owned and operated by Arqiva. History and development The station was constructed in the mid-1950s among the ruins of the Crystal Palace. The Aquarium on whose site it stands was destroyed in 1941 during the demolition of the Palace's north water tower. (John Logie Baird's earlier transmitter and TV studios were a separate development at the other end of the Palace and perished with it in 1936.) Its new tower was the tallest struct ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Analogue Television
Analog television is the original television technology that uses analog signals to transmit video and audio. In an analog television broadcast, the brightness, colors and sound are represented by amplitude, phase and frequency of an analog signal. Analog signals vary over a continuous range of possible values which means that electronic noise and interference may be introduced. Thus with analog, a moderately weak signal becomes snowy and subject to interference. In contrast, picture quality from a digital television (DTV) signal remains good until the signal level drops below a threshold where reception is no longer possible or becomes intermittent. Analog television may be wireless (terrestrial television and satellite television) or can be distributed over a cable network as cable television. All broadcast television systems used analog signals before the arrival of DTV. Motivated by the lower bandwidth requirements of compressed digital signals, beginning in the 20 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
YouTube
YouTube is a global online video platform, online video sharing and social media, social media platform headquartered in San Bruno, California. It was launched on February 14, 2005, by Steve Chen, Chad Hurley, and Jawed Karim. It is owned by Google, and is the List of most visited websites, second most visited website, after Google Search. YouTube has more than 2.5 billion monthly users who collectively watch more than one billion hours of videos each day. , videos were being uploaded at a rate of more than 500 hours of content per minute. In October 2006, YouTube was bought by Google for $1.65 billion. Google's ownership of YouTube expanded the site's business model, expanding from generating revenue from advertisements alone, to offering paid content such as movies and exclusive content produced by YouTube. It also offers YouTube Premium, a paid subscription option for watching content without ads. YouTube also approved creators to participate in Google's Google AdSens ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
