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PAL-S
PAL-S is the system of television receiver sets in the early days of the PAL system. Here PAL stands for ''Phase alternating at line rate'' and S stands for ''simple''. PAL system The color hue modulates the phase of a subcarrier named color carrier. In PAL system the polarity of the phase in each frame is reversed to neutralize the undesirable phase shifts introduced during transmission. Thus the effect of undesirable phase shift is positive in one frame and negative in the second frame. Averaging the two, the effect of the undesirable phase shifts in two consecutive frames cancel each other. The PAL-S receiver In the early days of the PAL system, it was proposed that, the human eye can average the slightly different color hues in two consecutive frames and perceive the original color. The television receiver sets which rely on optical averaging were called PAL-S receivers. The problems in PAL-S However, it soon turned out that the optical averaging had problems. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hanover Bars
Hanover bars, in one of the PAL television video formats, are an undesirable visual artifact in the reception of a television image. The name refers to the city of Hannover, in which the PAL system developer Telefunken Fernseh und Rundfunk GmbH was located. The PAL system encodes color as ''YUV''. The ''U'' (corresponding to ''B-Y'') and ''V'' (corresponding to ''R-Y'') signals carry the color information for a picture, with the phase of the ''V'' signal reversed (i.e. shifted through 180 degrees) on alternate lines (hence the name PAL, or ''phase alternate line''). This is done to cancel minor phase errors in the reception process. However, if gross errors occur, complementary errors from the ''V'' signal carry into the ''U'' signal, and thus visible stripes occur. Later PAL systems introduced alterations to ensure that Hanover bars do not occur, introducing a ''swinging burst'' to the color synchronization. Other PAL systems may handle this problem differently. Suppressio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chrominance Subcarrier
The chrominance subcarrier is a separate subcarrier signal that carries the color information during transmission of a composite video signal. It is modulated and synchronized using the colorburst signal and then attached to the back porch of the signal. By synchronizing the subcarrier with the local oscillator of the television receiver, the RGB The RGB color model is an additive color model in which the red, green and blue primary colors of light are added together in various ways to reproduce a broad array of colors. The name of the model comes from the initials of the three addi ... colors can be decoded successfully. References Video signal {{tv-tech-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Differential Gain
Differential gain is a kind of linearity distortion which affects the color saturation in TV broadcasting. Composite color video signal Composite color video signal (CCVS) consists of three terms: *Luminance (monochrome) signal *Auxiliary signals ( sync pulse and blanking level signals ) *Chrominance, which is actually a subcarrier modulated by chroma information The first two terms are usually called composite video signal (CVS) The modulation technique of the color subcarrier is quadrature amplitude modulation (QUAM) both in PAL and NTSC systems. The amplitude of the color signal represents the saturation ( purity) in both systems. On the other hand, the level of the CVS represents the brightness. So in order to reproduce the original vision in the receiver the ratio between these two pieces of information should be kept constant in the receiver. Nonlinearity in the broadcast system The main steps of visual signal from the scene to receiver screen (for terrestrial b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Differential Phase
Differential phase is a kind of linearity distortion which affects the color hue in TV broadcasting. Composite color video signal Composite color video signal (CCVS) consists of three terms: *Monochrome (luminance) signal *Auxiliary signals (sync pulse and blanking signals ) *Color signal, which is actually a subcarrier modulated by chroma information The first two terms are usually called composite video signal (CVS) The modulation technique of the color subcarrier is quadrature amplitude modulation (QAM) both in PAL and NTSC systems. The amplitude of the color signal represents the saturation of the color and the phase lag of the color signal with respect to a certain reference which is called colorburst represents the hue; i.e., each phase lag is assigned for a different color hue. So, in order to reproduce the original color in the receiver, the phase difference between the colorburst and the color signal must be kept constant throughout the broadcasting. The colorb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Television Technology
Large-screen television technology (colloquially big-screen TV) developed rapidly in the late 1990s and 2000s. Prior to the development of thin-screen technologies, rear-projection television was standard for larger displays, and jumbotron, a non-projection video display technology, was used at stadiums and concerts. Various thin-screen technologies are being developed, but only liquid crystal display (LCD), plasma display (PDP) and Digital Light Processing (DLP) have been publicly released. Recent technologies like organic light-emitting diode (OLED) as well as not-yet-released technologies like surface-conduction electron-emitter display (SED) or field emission display (FED) are in development to replace earlier flat-screen technologies in picture quality. Large-screen technologies have almost completely displaced cathode-ray tubes (CRT) in television sales due to the necessary bulkiness of cathode-ray tubes. The diagonal screen size of a CRT television is limited to abou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
