Digital cable ready
Encyclopedia
Cable-ready is a designation which indicates that a TV set or other television
-receiving device (such as a VCR or DVR
) is capable of receiving cable TV without a set-top box
.
The term originates with analog TV, which uses different frequencies for cable versus over-the-air
. This gives more channels, and at lower frequencies, so that early systems did not have to be so broadband
and were therefore less expensive to build.
In North America
, the VHF channels 2 to 13 are the same, while an extra 51 cable channels exist between there and over-the-air UHF channel 14. Thus, over-the-air channel 14 can be seen on cable channel 65. Conversely, those 51 extra channels (plus an additional five inserted at 95 to 99) cannot be seen at all on a device which is not cable-ready. A "181-channel tuner" receives 125 on cable (1 to 125), plus 10 (126 to 135) more for digital cable ready TVs, plus the 56 (14 to 69) which are not identical in both (2 to 13). Other cable channels, 0, 00 and 1, which along with channels 136-158 are ill-defined and thus rarely used, and often not included in otherwise cable-ready tuners. Those "lowest numbered" channels often reside between VHF channels four and five on HRC (harmonically related carrier) and IRC (incrementally related carrier) systems where the normally four MHz gap is increased to six MHz, wide enough for one NTSC channel. Similar situations exist in the rest of the world as well.
Another use of a cable-ready tuner
is for receiving amateur television
(ATV) in North America, where the main ATV band appears on cable channels 56 to 59, 57 being the most popular. Most repeater
s output on these channels, while input from amateur operators is often in another band.
s which feature built-in technology that allows consumers to receive SDTV
and HDTV
digital cable
programs. Usually this is a QAM tuner
, since over-the-air broadcasts are either COFDM (DVB-T
and ISDB-T) or 8VSB
(ATSC
-T). Some cable TV systems in North America use 16VSB
instead of 256QAM, for which there are no cable-ready devices. Only channels that are left unencrypted can be received using this method, however encrypted channels can be viewed without a set-top-box using systems such as a CableCard
or using a Downloadable Conditional Access System
.
Interactive digital cable ready or iDCR extends DCR. Unlike the DCR standard, iDCR supports interactive
customer features such as electronic program guide
s, pay-per-view
and video on demand
. Consumer devices which support iDCR also support the new OpenCable Application Platform
(OCAP) standard developed by CableLabs
.
Television
Television is a telecommunication medium for transmitting and receiving moving images that can be monochrome or colored, with accompanying sound...
-receiving device (such as a VCR or DVR
DVR
The initialism "DVR", when used by itself, can refer to:* Digital video recorder* Discrete valuation ring* Distance-vector routing* Direct volume rendering* Derwent Valley Railway * Devco Railway...
) is capable of receiving cable TV without a set-top box
Set-top box
A set-top box or set-top unit is an information appliance device that generally contains a tuner and connects to a television set and an external source of signal, turning the signal into content which is then displayed on the television screen or other display device.-History:Before the...
.
The term originates with analog TV, which uses different frequencies for cable versus over-the-air
Over-the-air
Over-the-air has several meanings, depending on context. *Generally, over-the-air is synonymous for wireless.*Specifically, over-the-air can have the following meanings or is used in the following contexts:...
. This gives more channels, and at lower frequencies, so that early systems did not have to be so broadband
Broadband
The term broadband refers to a telecommunications signal or device of greater bandwidth, in some sense, than another standard or usual signal or device . Different criteria for "broad" have been applied in different contexts and at different times...
and were therefore less expensive to build.
In North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
, the VHF channels 2 to 13 are the same, while an extra 51 cable channels exist between there and over-the-air UHF channel 14. Thus, over-the-air channel 14 can be seen on cable channel 65. Conversely, those 51 extra channels (plus an additional five inserted at 95 to 99) cannot be seen at all on a device which is not cable-ready. A "181-channel tuner" receives 125 on cable (1 to 125), plus 10 (126 to 135) more for digital cable ready TVs, plus the 56 (14 to 69) which are not identical in both (2 to 13). Other cable channels, 0, 00 and 1, which along with channels 136-158 are ill-defined and thus rarely used, and often not included in otherwise cable-ready tuners. Those "lowest numbered" channels often reside between VHF channels four and five on HRC (harmonically related carrier) and IRC (incrementally related carrier) systems where the normally four MHz gap is increased to six MHz, wide enough for one NTSC channel. Similar situations exist in the rest of the world as well.
Another use of a cable-ready tuner
Tuner
Tuner may refer to someone or something which adjusts or configures a mechanical, electronic, or musical device.- Electronic :* Antenna tuner, a device to adjust the resonance frequency of an antenna or transmission line...
is for receiving amateur television
Amateur television
Amateur television is the transmission of Broadcast quality video and audio over the wide range of frequencies of allocated for Radio amateur use. ATV is used for non-commercial experimentation, pleasure and public service events...
(ATV) in North America, where the main ATV band appears on cable channels 56 to 59, 57 being the most popular. Most repeater
Repeater
A repeater is an electronic device that receives asignal and retransmits it at a higher level and/or higher power, or onto the other side of an obstruction, so that the signal can cover longer distances.-Description:...
s output on these channels, while input from amateur operators is often in another band.
Digital cable
Digital cable-ready or DCR is a label used by manufacturers on new televisionTelevision
Television is a telecommunication medium for transmitting and receiving moving images that can be monochrome or colored, with accompanying sound...
s which feature built-in technology that allows consumers to receive SDTV
Standard-definition television
Sorete-definition television is a television system that uses a resolution that is not considered to be either enhanced-definition television or high-definition television . The term is usually used in reference to digital television, in particular when broadcasting at the same resolution as...
and HDTV
High-definition television
High-definition television is video that has resolution substantially higher than that of traditional television systems . HDTV has one or two million pixels per frame, roughly five times that of SD...
digital cable
Digital cable
Digital cable is a generic term for any type of cable television distribution using digital video compression or distribution. The technology was originally developed by Motorola.-Background:...
programs. Usually this is a QAM tuner
QAM tuner
QAM stands for quadrature amplitude modulation, the format by which digital cable channels are encoded and transmitted via cable television providers...
, since over-the-air broadcasts are either COFDM (DVB-T
DVB-T
DVB-T is an abbreviation for Digital Video Broadcasting — Terrestrial; it is the DVB European-based consortium standard for the broadcast transmission of digital terrestrial television that was first published in 1997 and first broadcast in the UK in 1998...
and ISDB-T) or 8VSB
8VSB
8VSB is the modulation method used for broadcast in the ATSC digital television standard. ATSC and 8VSB modulation is used primarily in North America; in contrast, the DVB-T standard uses COFDM....
(ATSC
ATSC
ATSC standards are a set of standards developed by the Advanced Television Systems Committee for digital television transmission over terrestrial, cable, and satellite networks....
-T). Some cable TV systems in North America use 16VSB
16VSB
16VSB is an abbreviation for 16-level vestigial sideband modulation, capable of transmitting four bits at a time.-How it works:Other slower but more rugged forms of VSB include 2VSB, 4VSB, and 8VSB...
instead of 256QAM, for which there are no cable-ready devices. Only channels that are left unencrypted can be received using this method, however encrypted channels can be viewed without a set-top-box using systems such as a CableCard
CableCARD
CableCARD is a special-use PCMCIA card that allows consumers in the United States to view and record digital cable television channels on digital video recorders, personal computers and television sets without the use of other equipment such as a set top box provided by a cable television company...
or using a Downloadable Conditional Access System
Downloadable Conditional Access System
Downloadable Conditional Access System or DCAS is a proposal advanced by CableLabs for secure software download of a specific Conditional Access client which controls digital rights management into an OCAP-compliant host consumer media device...
.
Interactive digital cable ready or iDCR extends DCR. Unlike the DCR standard, iDCR supports interactive
Interactive television
Interactive television describes a number of techniques that allow viewers to interact with television content as they view it.- Definitions :...
customer features such as electronic program guide
Electronic program guide
Electronic program guides and interactive program guides provide users of television, radio, and other media applications with continuously updated menus displaying broadcast programming or scheduling information for current and upcoming programming...
s, pay-per-view
Pay-per-view
Pay-per-view provides a service by which a television audience can purchase events to view via private telecast. The broadcaster shows the event at the same time to everyone ordering it...
and video on demand
Video on demand
Video on Demand or Audio and Video On Demand are systems which allow users to select and watch/listen to video or audio content on demand...
. Consumer devices which support iDCR also support the new OpenCable Application Platform
OpenCable Application Platform
The OpenCable Application Platform, or OCAP, is an operating system layer designed for consumer electronics that connect to a cable television system, the Java-based middleware portion of the platform. Unlike operating systems on a personal computer, the cable company controls what OCAP programs...
(OCAP) standard developed by CableLabs
CableLabs
Founded in 1988 by cable television operating companies, Cable Television Laboratories, Inc. is a not-for-profit research and development consortium that has cable operators as its members. System operators from around the world are eligible to be members. Members dues are based on revenue...
.