Digital cable and Related Topics

Cable television

System of delivering television programming to consumers via radio frequency signals transmitted through coaxial cables, or in more recent systems, light pulses through fibre-optic cables.

A set-top box, an electronic device which cable subscribers use to connect the cable signal to their television sets. Presented unit is a Cisco RNG200N for QAM digital cable television system used in North America.

A cable television distribution box (left) in the basement of a building in Germany (Kabel BW network, now Vodafone), with a splitter (right) which supplies the signal to separate cables which go to different rooms

Diagram of a modern hybrid fiber-coaxial cable television system. At the regional headend, the TV channels are sent multiplexed on a light beam which travels through optical fiber trunklines, which fan out from distribution hubs to optical nodes in local communities. Here the light signal from the fiber is translated to a radio frequency electrical signal, which is distributed through coaxial cable to individual subscriber homes.

Analog television was standard in the 20th century, but since the 2000s, cable systems have been upgraded to digital cable operation.

Analog QAM: measured PAL color bar signal on a vector analyzer screen.

QAM (television)

Digital television standard using quadrature amplitude modulation.

It is also common for cable providers to falsely insist that a set-top box from the cable company is required to watch all digital cable channels, including unencrypted channels, even though QAM channels may be distributed via their system.

ATSC standards

American set of standards for digital television transmission over terrestrial, cable and satellite networks.

Digital terrestrial television broadcasting systems. Countries using ATSC are shown in orange.

In recent years, cable operators have become accustomed to compressing standard-resolution video for digital cable systems, making it harder to find duplicate 6 MHz channels for local broadcasters on uncompressed "basic" cable.

Digital video recorder

Electronic device that records video in a digital format to a disk drive, USB flash drive, SD memory card, SSD or other local or networked mass storage device.

V+, a combined digital video recorder and cable TV receiver.

Back view of a TiVo Series2 5xx-generation unit

Side view of an LCD monitor with built-in DVR

Embeddable DVR with incremental encoder interface for position tracking

Lorex 4K NVR, a security digital video recorder

Recording satellite television or digital cable signals on a digital video recorder can be more complex than recording analog signals or broadcast digital signals.

Quadrature amplitude modulation

Name of a family of digital modulation methods and a related family of analog modulation methods widely used in modern telecommunications to transmit information.

Digital 16-QAM with example constellation points

Constellation points for 4-QAM, 16-QAM, 32-QAM, and 64-QAM overlapped

Bit-loading (bits per QAM constellation) on an ADSL line

64-QAM and 256-QAM are often used in digital cable television and cable modem applications.

A commercial IP telephone, with keypad, control keys, and screen functions to perform configuration and user features.

Cable telephony

Form of digital telephony over cable TV networks.

The biggest advantage to digital cable telephone service is similar to the advantage of digital cable television, namely that data can be compressed, resulting in much less bandwidth used than a dedicated analog circuit-switched service.

Electronic programming guide interface in MythTV.

Pay-per-view

Type of pay television or webcast service that enables a viewer to pay to watch individual events via private telecast.

In the past, PPV was often used to distribute telecasts of feature films, as well as adult content such as pornographic films, but the growth of digital cable and streaming media caused these uses to be subsumed by video on demand systems (which allow viewers to purchase and view pre-recorded content at any time) instead, leaving PPV to focus primarily on live event programs and combat sports.

Categorization for signal modulation based on data and carrier types

8VSB

Modulation method used for broadcast in the ATSC digital television standard.

16VSB was notably intended to be used for ATSC digital cable, but quadrature amplitude modulation (QAM) has become the de facto industry standard instead as it is cheap and readily available.

MPEG-2 is used in Digital Video Broadcast and DVDs. The MPEG transport stream, TS, and MPEG program stream, PS, are container formats.

Virtual channel

Method of remapping the program number as used in H.222 Program Association Tables and Program Mapping Tables to a channel number that can be entered via digits on a receiver's remote control.

This is true of digital cable and satellite radio services, as well.

Comparison of frequency band designations

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.

Operating in a sector traditionally lacking subchannels, digital cable television provider Music Choice packages its nearly 50 music channels (including Music Choice Play) as digital subchannels of one channel.