Digital cable in the context of Cable converter box

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 fibre-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, or satellite television, in which the television signal is transmitted over-the-air by radio waves from a communications satellite 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.

A cable channel (sometimes known as a cable network) is a television network available via cable television. Many of the same channels are distributed through satellite television. Alternative terms include non-broadcast channel or programming service, the latter being mainly used in legal contexts. The abbreviation CATV is used in the US for cable television and originally stood for community antenna television, from cable television's origins in 1948; in areas where over-the-air TV reception was limited by distance from transmitters or mountainous terrain, large community antennas were constructed, and cable was run from them to individual homes.

QAM is a digital television standard using quadrature amplitude modulation. It is the format by which digital cable channels are encoded and transmitted via cable television providers. QAM is used in a variety of communications systems such as Dial-up modems and Wi-Fi. In cable systems, a QAM tuner is linked to the cable in a manner that is equivalent to an ATSC tuner which is required to receive over-the-air (OTA) digital channels broadcast by local television stations when attached to an antenna. Most new HDTV digital televisions support both of these standards. QAM uses the same 6 MHz bandwidth as ATSC, using a standard known as ITU-T Recommendation J.83 Annex B ("J.83b").

The digital television transition, also called the digital switchover (DSO), the analogue switch/sign-off (ASO), the digital migration, or the analogue shutdown, is the process in which older analogue television broadcasting technology is converted to and replaced by digital television. Conducted by individual nations on different schedules, this primarily involves the conversion of analogue terrestrial television broadcasting infrastructure to Digital terrestrial television (DTT), a major benefit being extra frequencies on the radio spectrum and lower broadcasting costs, as well as improved viewing qualities for consumers.

The transition may also involve analogue cable conversion to digital cable or Internet Protocol television, as well as analogue to digital satellite television. Transition of land based broadcasting had begun in some countries around 2000. By contrast, transition of satellite television systems was well underway or completed in many countries by this time. It is an involved process because the existing analogue television receivers owned by viewers cannot receive digital broadcasts; viewers must either purchase new digital TVs, or digital converter boxes which have a digital tuner and change the digital signal to an analogue signal or some other form of a digital signal (i.e. HDMI) which can be received on the older TV. Usually during a transition, a simulcast service is operated where a broadcast is made available to viewers in both analogue and digital at the same time. As digital becomes more popular, it is expected that the existing analogue services will be removed. In most places this has already happened, where a broadcaster has offered incentives to viewers to encourage them to switch to digital. Government intervention usually involves providing some funding for broadcasters and, in some cases, monetary relief to viewers, to enable a switchover to happen by a given deadline. In addition, governments can also have a say with the broadcasters as to what digital standard to adopt – either DVB-T2 ATSC Governments can also require all receiving equipment sold in a country to support the necessary digital 'tuner'.

Advanced Television Systems Committee (ATSC) standards are an international set of standards for broadcast and digital television transmission over terrestrial, cable and satellite networks. It is largely a replacement for the analog NTSC standard. Like NTSC, ATSC is used mostly in the United States, Mexico, Canada, South Korea, and Trinidad and Tobago. Several former NTSC users like Japan have not used ATSC during their digital television transition, because they adopted other systems like ISDB developed by Japan and DVB developed in Europe, for example.

The ATSC standards were developed in the early 1990s by the 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 standard. Key among these is the 8VSB modulation system used for over-the-air broadcasts. ATSC 1.0 technology was primarily developed with patent contributions from LG Electronics, which held most of the patents for the ATSC standard.