Digital cable is any type of cable television distribution using digital video compression for USE. 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 format, 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.
In 1990, General Instrument (now owned by ARRIS Group) demonstrated that it was possible to use digital compression to deliver high quality HDTV in a standard 6 MHz television channel. Using the same technology General Instrument (GI) demonstrated the digital transmission of multiple high quality standard definition programs in a 6 MHz cable channel.
In the 1990s cable providers began to invest heavily in this new multi-channel digital TV technology to expand the number of channels and services available to subscribers. Increased competition and programming choices from Direct-broadcast satellite services such as DirecTV, Dish Network, and PrimeStar caused cable providers to seek new ways to provide more programming. Customers were increasingly interested in more channels, pay-per-view programming, digital music services, and high speed internet services. By 2000, most cable providers in the US were offering some form of digital cable TV to their customers.
Digital cable technology has allowed cable providers to compress video channels so that they take up less frequency space and to offer various two-way communication capabilities. This has enabled digital cable providers to offer more channels, video on demand services (without use of a telephone line), telephone services, high speed internet services, and interactive television services. In addition, digital cable technology allows for error correction to ensure the quality of the received signal and uses a secure digital distribution system (i.e. a secure encrypted signal to prevent eavesdropping and theft of service.)
Most digital cable providers use QAM for video services and DOCSIS standards for data services. Some providers have also begun to roll out video services using IPTV or Switched video.
Digital cable technology can allow many TV channels to occupy the frequency space that would normally be occupied by a single analog cable TV channel. The number of channels placed on a single analog frequency depends on the compression used. Many cable providers are able to fit about 10 digital SD channels or 2 digital HD channels on a single analog channel frequency. Some providers are able to squeeze more channels onto a single frequency with higher compression, but often this can cause the video quality of the channel to degrade.
The subchannel is a logical channel of data within the physical channel. Technically there can be up to 1024 subchannels in a physical channel, though in practice only a few are used (as the bandwidth must be divided among all the subchannels).
There are two ways providers try to make this easier for consumers. The first, accomplished through PSIP, is where program and channel information is broadcast along with the video, allowing the consumer's decoder (set-top box or display) to automatically identify the many channels and subchannels.
The second (also accomplished through PSIP) is where, in an effort to hide subchannels entirely, many cable companies map virtual channel numbers to underlying physical and sub-channels. For example, a cable company might call channel 5-1 "channel 732" and channel 5-2 "channel 733". This also allows the cable company to change the frequency of a channel without changing what the customer sees as a channel number. In such arrangements, the physical/sub-channel numbers are called the "QAM channel", and the alternative channel designation is called the "mapped channel", "virtual channel", or simply "channel".
In theory, a set-top box can decode the PSIP information from every channel it receives and use that information to build the mapping between QAM channel and virtual channel. However, cable companies do not always reliably transmit PSIP information. Alternatively, CableCards receive the channel mapping and can communicate that to the set-top box.blogging with google sites blogging without social media bloggingx bloggingx pro bloggingx pro free download xkcd blogging xanga blogging blogging alert xyz explain xkcd blogging blogging your passion blogging youtube blogging your passion podcast blogging youtube channel name blogging your way blogging your way by holly becker blogging your way to the front row blogging your book blogging zones blogging zelda blogging zarada blogging zenith zen cart blogging blogging in zimbabwe blogging in zambia blogging success zone blogging about books blogging about tv shows blogging about food blogging about my life blogging about your personal life blogging about art blogging about pets blogging after retirement bloating after ovulation blogging income after 1 year what after blogging career after blogging retired now what blogs can i retire now blog to blog or not to blog blogging is blogging about blogging blogging as a hobby blogging as a job blogging as a business model blogging as an educational tool blogging as a nurse blogging at medium blogging at work blogging at fl250 blogging at 70 blogging at 40 blogging at 60 blogging at college blogging at the limit before blogging blogging platform before know before blogging tips before blogging considerations before blogging blogging behind the scenes psychology behind blogging secret behind blogging meaning behind blogging difference between blogging and vlogging difference between blogging and microblogging difference between blogging and content writing difference between blogging and website difference between blogging and podcasting difference between blogging and journalism difference between blogging and affiliate marketing difference between blogging and social media blogging beyond the classroom moving beyond blogging beyond blogging blogging by sophia lee blogging by numbers blogging by google blogging by maya bloggings by boz blogging by email blogging by definition blogging step by step blogging during covid 19 blogging during a divorce blogging during weight loss blogging during war travel blogging during covid covid-19 blog topics covid blog ideas blogging quizlet blogging from your phone blogging from paradise blogging from scratch blogging from iphone blogging from ipad blogging from the heart blogging from home blogging from home jobs in blog or on blog in your blog or on your blog blogging in the elementary classroom blogging in education blogging in google blogging in 2022 blogging in wordpress turning blogging into a business turn blogging into career translate blogging into kannada blogging translate into bengali getting into blogging fall into blogging how to make money while blogging blogging like blogging like apps blogging like website blogging like site blogging platforms like medium blogging sites like tumblr blogging sites like medium blogging near philadelphia blogging classes near me blogging course near me blogging workshops near me blogging coaching near me blogging groups near me blogging events near me blogging of photography blogging of e commerce blogging of music blogging of art blogging of cars blogging of computer blogging of a product blogging of future blogging blast off guest blogging off page write off blogging expenses money off blogging blogging takes off traduzione blogging on google opposite of blogging blogging out meaning is blogging out is blogging out of date blogging is dying out what do you mean by blog blogging over thyme blogging over wine blogging over 50 blogging over 40 blogging over advantages of blogging over social media building over blogging over blogging definition blogging past participle blogging in past tense blogging pro jobs bloggingpro reviews bloggingpro wordpress theme bloggingpro theme pro blogging tips pro blogging tips blogspot pro blogging idea blogging through instagram blogging through google blogging through mobile blogging through wordpress blogging through facebook blogging through the fourth dimension blogging through pinterest blogging through squarespace earning thru blogging can i earn from blogging can bloggers make good money blogging to earn money blogging to win course review blogging to make money online blogging to win.com blogging to relieve stress