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Channel Memory
{{unreferenced, date=May 2009 An automatic channel memory system (ACMS) is a system in which a digitally controlled radio tuner such as a TV set or VCR could search and memorize TV channels automatically. While more common in television, it can also be used to store presets for radio stations. This is often called a channel scan, though that may also refer to a "preview" mode which plays each station it finds for a few seconds and then moves on to the next, without affecting memory. Channel scanning A typical TV device allows an automatic channel scan to be performed from a menu accessed by a button on the TV set, or sometimes only on the remote control. This applied first to analog TV sets — sometimes those with digital LED displays, or later always those with on-screen displays. These simply searched for the video carrier signal on every channel. (Before the advent of ACMS, many sets would search for the next channel every time it was changed.) It now also applies to digit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radio Tuner
A tuner is a subsystem that receives radio frequency (RF) transmissions, such as FM broadcasting, and converts the selected carrier frequency and its associated bandwidth into a fixed frequency that is suitable for further processing, usually because a lower frequency is used on the output. Broadcast FM/ AM transmissions usually feed this intermediate frequency (IF) directly into a demodulator that converts the radio signal into audio-frequency signals that can be fed into an amplifier to drive a loudspeaker. More complex transmissions like PAL/NTSC (TV), DAB (digital radio), DVB-T/DVB-S/DVB-C (digital TV) etc. use a wider frequency bandwidth, often with several subcarriers. These are transmitted inside the receiver as an intermediate frequency (IF). Subcarriers are then processed like real radio transmissions, but the whole bandwidth is sampled with an analog-to-digital converter (A/D) at a rate faster than the Nyquist rate (that is, at least twice the IF frequency). A tune ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ATSC
Advanced Television Systems Committee (ATSC) standards are an American set of standards for digital television transmission over terrestrial, cable and satellite networks. It is largely a replacement for the analog NTSC standard and, like that standard, is used mostly in the United States, Mexico, Canada, and South Korea. Several former NTSC users, such as Japan, have not used ATSC during their digital television transition, because they adopted other systems such as ISDB developed by Japan, and Digital Video Broadcasting, DVB developed in Europe, for example. The ATSC standards were developed in the early 1990s by the Grand Alliance (HDTV), Grand Alliance, a consortium of electronics and telecommunications companies that assembled to develop a specification for what is now known as HDTV. The standard is now administered by the Advanced Television Systems Committee. It includes a number of patented elements, and licensing is required for devices that use these parts of the stan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Power Outage
A power outage (also called a powercut, a power out, a power failure, a power blackout, a power loss, or a blackout) is the loss of the electrical power network supply to an end user. There are many causes of power failures in an electricity network. Examples of these causes include faults at power stations, damage to electric transmission lines, substations or other parts of the distribution system, a short circuit, cascading failure, fuse or circuit breaker operation. Power failures are particularly critical at sites where the environment and public safety are at risk. Institutions such as hospitals, sewage treatment plants, and mines will usually have backup power sources such as standby generators, which will automatically start up when electrical power is lost. Other critical systems, such as telecommunication, are also required to have emergency power. The battery room of a telephone exchange usually has arrays of lead–acid batteries for backup and also a socket ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Direct Tuning
Direct may refer to: Mathematics * Directed set, in order theory * Direct limit of (pre), sheaves * Direct sum of modules, a construction in abstract algebra which combines several vector spaces Computing * Direct access (other), a method of accessing data in a database * Direct connect (other), various methods of telecommunications and computer networking * Direct memory access, access to memory by hardware subsystems independently of the CPU Entertainment * ''Direct'' (Tower of Power album) * ''Direct'' (Vangelis album) * ''Direct'' (EP), by The 77s Other uses * Nintendo Direct, an online presentation frequently held by Nintendo * Mars Direct, a proposal for a crewed mission to Mars * DIRECT, a proposed space shuttle-derived launch vehicle * DirectX, a proprietary dynamic media platform * Direct current, a direct flow of electricity * Direct examination, the in-trial questioning of a witness by the party who has called him or her to testify See ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
LPTV
Low-power broadcasting is broadcasting by a broadcast station at a low transmitter power output to a smaller service area than "full power" stations within the same region. It is often distinguished from "micropower broadcasting" (more commonly " microbroadcasting") and broadcast translators. LPAM, LPFM and LPTV are in various levels of use across the world, varying widely based on the laws and their enforcement. Canada Radio communications in Canada are regulated by the Radio Communications and Broadcasting Regulatory Branch, a branch of Industry Canada, in conjunction with the Canadian Radio-television and Telecommunications Commission (CRTC). Interested parties must apply for both a certificate from Industry Canada and a license from CRTC in order to operate a radio station. Industry Canada manages the technicalities of spectrum space and technological requirements whereas content regulation is conducted more so by CRTC. LPFM is broken up into two classes in Canada, Low (50 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Digital Subchannel
In broadcasting, digital subchannels are a method of transmitting more than one independent program stream simultaneously from the same digital radio or television station on the same radio frequency channel. This is done by using data compression techniques to reduce the size of each individual program stream, and multiplexing to combine them into a single signal. The practice is sometimes called "multicasting". ATSC television United States The ATSC digital television standard used in the United States supports multiple program streams over-the-air, allowing television stations to transmit one or more subchannels over a single digital signal. A virtual channel numbering scheme distinguishes broadcast subchannels by appending the television channel number with a period digit (".xx"). Simultaneously, the suffix indicates that a television station offers additional programming streams. By convention, the suffix position ".1" is normally used to refer to the station's main digi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
TV Antenna
Television, sometimes shortened to TV, is a telecommunication medium for transmitting moving images and sound. The term can refer to a television set, or the medium of television transmission. Television is a mass medium for advertising, entertainment, news, and sports. Television became available in crude experimental forms in the late 1920s, but only after several years of further development was the new technology marketed to consumers. After World War II, an improved form of black-and-white television broadcasting became popular in the United Kingdom and the United States, and television sets became commonplace in homes, businesses, and institutions. During the 1950s, television was the primary medium for influencing public opinion.Diggs-Brown, Barbara (2011''Strategic Public Relations: Audience Focused Practice''p. 48 In the mid-1960s, color broadcasting was introduced in the U.S. and most other developed countries. The availability of various types of archival stora ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antenna Rotator
An antenna rotator (or antenna rotor) is a device used to change the orientation, within the horizontal plane, of a directional antenna. Most antenna rotators have two parts, the rotator unit and the controller. The controller is normally placed near the equipment which the antenna is connected to, while the rotator is mounted on the antenna mast directly below the antenna. Rotators are commonly used in amateur radio and military communications installations. They are also used with TV and FM antennas, where stations are available from multiple directions, as the cost of a rotator is often significantly less than that of installing a second antenna to receive stations from multiple directions. Rotators are manufactured for different sizes of antennas and installations. For example, a consumer TV antenna rotator has enough torque to turn a TV/FM or small ham antenna. These units typically cost around US$70 . Heavy-duty ham rotators are designed to turn extremely large, heavy, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radio Propagation
Radio propagation is the behavior of radio waves as they travel, or are propagated, from one point to another in vacuum, or into various parts of the atmosphere. As a form of electromagnetic radiation, like light waves, radio waves are affected by the phenomena of reflection, refraction, diffraction, absorption, polarization, and scattering. Understanding the effects of varying conditions on radio propagation has many practical applications, from choosing frequencies for amateur radio communications, international shortwave broadcasters, to designing reliable mobile telephone systems, to radio navigation, to operation of radar systems. Several different types of propagation are used in practical radio transmission systems. ''Line-of-sight propagation'' means radio waves which travel in a straight line from the transmitting antenna to the receiving antenna. Line of sight transmission is used for medium-distance radio transmission, such as cell phones, cordless phones, walkie- ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Digital Television Adapter
A digital television adapter (DTA), commonly known as a converter box or decoder box, is a television tuner that receives a digital television (DTV) transmission, and converts the digital signal into an analog signal that can be received and displayed on an analog television set. Some also have an HDMI output since some TVs with HDMI do not have a digital tuner. The input digital signal may be over-the-air terrestrial television signals received by a television antenna, or signals from a digital cable system. It normally does not refer to satellite TV, which has always required a set-top box either to operate the big satellite dish, or to be the integrated receiver/decoder (IRD) in the case of direct-broadcast satellites (DBS). In North America and South Korea, these ATSC tuner boxes convert from ATSC to NTSC, while in most of Europe and other places such as Australia and most Asian countries, they convert from Digital Video Broadcasting (DVB) to PAL, and in Japan, the Philipp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Favorites
In the context of the World Wide Web, a bookmark is a Uniform Resource Identifier (URI) that is stored for later retrieval in any of various storage formats. All modern web browsers include bookmark features. Bookmarks are called favorites or Internet shortcuts in Internet Explorer and Microsoft Edge, and by virtue of that browser's large market share, these terms have been synonymous with ''bookmark'' since the First Browser War. Bookmarks are normally accessed through a menu in the user's web browser, and folders are commonly used for organization. In addition to bookmarking methods within most browsers, many external applications offer bookmark management. Bookmarks have been incorporated in browsers since the ViolaWWW browser in 1992, and Mosaic browser in 1993. Bookmark lists were called ''Hotlists'' in Mosaic and in previous versions of Opera; this term has faded from common use. Cello, another early browser, also had bookmarking features. With the advent of social bookma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
