An analog signal is any continuous signal for which the time-varying feature (variable) of the signal is a representation of some other time varying quantity, i.e., analogous to another time varying signal. For example, in an analog audio signal, the instantaneous voltage of the signal varies continuously with the pressure of the sound waves. It differs from a digital signal, in which the continuous quantity is a representation of a sequence of discrete values which can only take on one of a finite number of values. The term analog signal usually refers to electrical signals; however, mechanical, pneumatic, hydraulic, human speech, and other systems may also convey or be considered analog signals.
Cable television is a system of delivering television programming to consumers via radio frequency (RF) signals transmitted through coaxial cables, or in more recent systems, light pulses through fiber-optic cables. This contrasts with broadcast television, in which the television signal is transmitted over the air by radio waves and received by a television antenna attached to the television; or satellite television, in which the television signal is transmitted by a communications satellite orbiting the Earth and received by a satellite dish on the roof. FM radio programming, high-speed Internet, telephone services, and similar non-television services may also be provided through these cables. Analog television was standard in the 20th century, but since the 2000s, cable systems have been upgraded to digital cable operation.
Digital television (DTV) is the transmission of television signals, including the sound channel, using digital encoding, in contrast to the earlier television technology, analog television, in which the video and audio are carried by analog signals. It is an innovative advance that represents the first significant evolution in television technology since color television in the 1950s. Digital TV transmits in a new image format called HDTV, with greater resolution than analog TV, in a wide screen aspect ratio similar to recent movies in contrast to the narrower screen of analog TV. It makes more economical use of scarce radio spectrum space; it can transmit multiple channels, up to 7, in the same bandwidth occupied by a single channel of analog television, and provides many new features that analog television cannot. A transition from analog to digital broadcasting began around 2006 in some countries, and many industrial countries have now completed the changeover, while other countries are in various stages of adaptation. Different digital television broadcasting standards have been adopted in different parts of the world; below are the more widely used standards:
In electronics and telecommunications, modulation is the process of varying one or more properties of a periodic waveform, called the carrier signal, with a modulating signal that typically contains information to be transmitted. Most radio systems in the 20th century used frequency modulation (FM) or amplitude modulation (AM) for radio broadcast.
A set-top box (STB) or set-top unit (STU) is an information appliance device that generally contains a TV-tuner input and displays output to a television set and an external source of signal, turning the source signal into content in a form that then be displayed on the television screen or other display device. They are used in cable television, satellite television, and over-the-air television systems, as well as other uses.
Data transmission is the transfer of data over a point-to-point or point-to-multipoint communication channel. Examples of such channels are copper wires, optical fibers, wireless communication channels, storage media and computer buses. The data are represented as an electromagnetic signal, such as an electrical voltage, radiowave, microwave, or infrared signal.
Digital audio is sound that has been recorded in, or converted into, digital form. In digital audio, the sound wave of the audio signal is encoded as numerical samples in continuous sequence. For example, in CD audio, samples are taken 44100 times per second each with 16 bit sample depth. Digital audio is also the name for the entire technology of sound recording and reproduction using audio signals that have been encoded in digital form. Following significant advances in digital audio technology during the 1970s, it gradually replaced analog audio technology in many areas of audio engineering and telecommunications in the 1990s and 2000s.
Digital Visual Interface (DVI) is a video display interface developed by the Digital Display Working Group (DDWG). The digital interface is used to connect a video source, such as a video display controller, to a display device, such as a computer monitor. It was developed with the intention of creating an industry standard for the transfer of digital video content.
Digital cable is the distribution of cable television using digital video compression for distribution. The technology was originally developed by General Instrument before being acquired by Motorola and subsequently acquired by ARRIS Group. Cable companies converted to digital systems during the 2000s, around the time that television signals were converted to the digital HDTV standard, which was not compatible with earlier analog cable systems. In addition to providing higher resolution HD video, digital cable systems provide expanded services such as pay-per-view programming, cable internet access and cable telephone services. Most digital cable signals are encrypted, which reduced the high incidence of cable theft which occurred in analog systems.
Alabama Public Television is a state network of PBS member television stations serving the U.S. state of Alabama. It is operated by the Alabama Educational Television Commission, which holds the licenses for all the PBS member stations licensed in the state. The broadcast signals of the nine stations cover almost all of the state, as well as parts of Florida, Georgia, Mississippi and Tennessee. The network produces public affairs and documentary programming; broadcast and online education programs for classroom use and teacher professional development; and electronic field trips serving K-12 students.
WFNA, virtual channel 55, is a CW-affiliated television station serving Mobile, Alabama and Pensacola, Florida, United States that is licensed to Gulf Shores, Alabama. The station is owned by the Nexstar Media Group, as part of a duopoly with Mobile-licensed CBS affiliate WKRG-TV. The two stations share studios with several radio stations owned by iHeartMedia on Broadcast Drive in southwest Mobile; WFNA's transmitter is located near Robertsdale.
KSCE, virtual channel 38, is a religious independent television station licensed to El Paso, Texas, United States and also serving Las Cruces, New Mexico. The station is owned by Channel 38 Christian Television. KSCE's studios are located on Wyoming Avenue in northeast El Paso, and its transmitter is located atop the Franklin Mountains on the El Paso city limits.
South Dakota Public Broadcasting (SDPB) is a state network of non-commercial educational television and radio stations serving the U.S. state of South Dakota. The stations are operated by the South Dakota Bureau of Information and Telecommunication, an agency of the state government which holds the licenses for all of the Public Broadcasting Service (PBS) and National Public Radio (NPR) member stations licensed in South Dakota except KRSD in Sioux Falls, which is owned and run by Minnesota Public Radio, and KAUR in Sioux Falls, which is owned by Augustana University and operated by MPR. SDPB's studios and offices are located in the Al Neuharth Media Center at 500 N. Dakota Avenue on the University of South Dakota campus in Vermillion.
The Arkansas Educational Television Network (AETN) is a state network of Public Broadcasting Service (PBS) member television stations serving the U.S. state of Arkansas. It is operated by the Arkansas Educational Television Commission, an agency of the Arkansas state government that holds the licenses for all the PBS member stations licensed in the state. The broadcast signals of the six stations that are part of the public television network cover almost all of the state, as well as portions of Mississippi, Tennessee, Missouri, Oklahoma, Texas and Louisiana.
KYES-TV, virtual channel 5, is a MyNetworkTV-affiliated television station licensed to Anchorage, Alaska, United States. The station is owned by Gray Television, as part of a duopoly with NBC affiliate KTUU-TV. The two stations share studios on East 40th Avenue in Anchorage; KYES-TV's transmitter is located in Knik, Alaska. On cable, the station is available on GCI channel 5. It is also carried on DirecTV and Dish Network in the Anchorage television market.
Nebraska Educational Telecommunications (NET) is a state network of public radio and television stations in the U.S. state of Nebraska and is based in Lincoln. It is operated by the Nebraska Educational Telecommunications Commission. The television stations are all members of PBS, while the radio stations are members of NPR.
Mississippi Public Broadcasting is the public broadcasting state network in Mississippi, United States. It is owned by the Mississippi Authority for Educational Television, an agency of the Mississippi state government that holds the licenses for all of the PBS and NPR member stations in the state.
A digital television adapter (DTA), commonly known as a converter 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. 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).
Analog passthrough is a feature found on some digital-to-analog television converter boxes. Boxes without analog passthrough only allow digital TV to be viewed on older, analog-only TVs. Those with analog passthrough allow both digital and analog television to be viewed on older TVs.
