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DVB-C
 
 
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DVB-C stands for Digital Video Broadcasting - Cable and it is the DVB European consortium standard for the broadcast transmission of digital television
Digital television

Digital television is the sending and receiving of moving images and sound by Discrete signal signals, in contrast to the Analog television used by analog TV....
 over cable
Coaxial cable

Coaxial cable is a cable consisting of an inner conductor, surrounded by a tubular insulating layer typically made from a flexible material with a high dielectric constant, all of which is then surrounded by another conductive layer , and then finally covered again with a thin insulating layer on the outside....
. This system transmits an MPEG-2
MPEG-2

MPEG-2 is a standard for "the generic coding of moving pictures and associated audio information". It describes a combination of Lossy compression video compression and lossy audio data compression methods which permit storage and transmission of movies using currently available storage media and transmission bandwidth....
 or MPEG-4
MPEG-4

MPEG-4 is a collection of methods defining Video compression of audio and visual digital data. It was introduced in late 1998 and designated a standardization for a group of sound and video coding formats and related technology agreed upon by the International Organization for Standardization/International Electrotechnical Commission Moving...
  family digital audio/video stream, using a QAM modulation with channel coding.

DVB-C2
On February 18, 2008 it was announced that a new standard - DVB-C2 - would be developed during 2008.






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DVB-C stands for Digital Video Broadcasting - Cable and it is the DVB European consortium standard for the broadcast transmission of digital television
Digital television

Digital television is the sending and receiving of moving images and sound by Discrete signal signals, in contrast to the Analog television used by analog TV....
 over cable
Coaxial cable

Coaxial cable is a cable consisting of an inner conductor, surrounded by a tubular insulating layer typically made from a flexible material with a high dielectric constant, all of which is then surrounded by another conductive layer , and then finally covered again with a thin insulating layer on the outside....
. This system transmits an MPEG-2
MPEG-2

MPEG-2 is a standard for "the generic coding of moving pictures and associated audio information". It describes a combination of Lossy compression video compression and lossy audio data compression methods which permit storage and transmission of movies using currently available storage media and transmission bandwidth....
 or MPEG-4
MPEG-4

MPEG-4 is a collection of methods defining Video compression of audio and visual digital data. It was introduced in late 1998 and designated a standardization for a group of sound and video coding formats and related technology agreed upon by the International Organization for Standardization/International Electrotechnical Commission Moving...
  family digital audio/video stream, using a QAM modulation with channel coding.

DVB-C2


On February 18, 2008 it was announced that a new standard - DVB-C2 - would be developed during 2008. The new standard should be ready very early in 2009.

The DVB TM-C2 issued on February 18. 2008 a "Call for Technologies" for DVB-C2. Proposals including simulation programs and information on patent rights can be submitted until June 16. 2008. The draft standard should be ready very early 2009.

A very core point is the expectation that DVB-C2 will be the last cable standard ever, i.e. there will never be a -C3 standard.

"The results of the DVB-C2 Study Mission already provided clear indications that technologies are available allowing the performance of the second generation DVB cable transmission system to get so close to the theoretical Shannon Limit that any further improvements in the future would most likely not be able to justify the introduction of a disruptive third generation of cable transmission system." (DVB-C2 CfT)

The new standard may be ready for use late 2009 or more likely sometime during 2010 depending on the individual cable companies.

Technical description of the DVB-C transmitter

With reference to the figure, a short description of the single processing blocks follows.

  • Source coding
    Source coding

    In information theory, Shannon's source coding theorem establishes the limits to possible data compression, and the operational meaning of the Shannon entropy....
     and MPEG-2 multiplexing
    Multiplexing

    In telecommunications and computer networks, multiplexing is a process where multiple analog message signals or digital data streams are combined into one signal over a shared medium....
     (MUX):     video, audio, and data streams are multiplexed into an MPEG-2 Programme Stream
    Program stream

    Program stream is a container format for multiplexing digital audio, video and more. The PS format is specified in MPEG-1 Systems and MPEG-2 Part 1, Systems ....
     (PS). One or more PSs are joined together into a MPEG-2 Transport Stream
    Transport stream

    Transport stream is a communications protocol for Digital audio, Digital video, and Program and System Information Protocol which is specified in MPEG-2 Part 1, Systems ....
     (TS). This is the basic digital stream which is being transmitted and received by home Set Top Boxes (STB). Allowed bitrate
    Bitrate

    In telecommunications and computing, bitrate is the number of bits that are conveyed or processed per unit of time.The bit rate is quantified using the Data rate units unit, often in conjunction with an SI prefix such as kilo- , mega- , giga- or tera- ....
    s for the transported MPEG-2 depend on a number of modulation parameters: it can range from about 6 to about 64 Mbit/s (see the bottom figure for a complete listing).


  • MUX adaptation and energy dispersal: the MPEG-2 TS is identified as a sequence of data packets, of fixed length (188 bytes). With a technique called energy dispersal, the byte sequence is decorrelated
    Correlation

    In probability theory and statistics, correlation indicates the strength and direction of a linear relationship between two random variables....
    .


  • External encoder: a first level of protection is applied to the transmitted data, using a nonbinary block code
    Block code

    In computer science, a block code is a type of channel coding. It adds redundancy to a message so that, at the receiver, one can decode with minimal errors, provided that the information rate would not exceed the channel capacity....
    , a Reed-Solomon RS (204, 188) code, allowing the correction of up to a maximum of 8 wrong bytes for each 188-byte packet.


  • External interleaver
    Interleaving

    Interleaving in computer science is a way to arrange data in a non-contiguous way in order to increase performance.It is used in:* time-division multiplexing in telecommunications...
    :     convolutional interleaving is used to rearrange the transmitted data sequence, such way it becomes more rugged to long sequences of errors.


  • Byte/m-tuple conversion: data bytes are encoded into bit m-tuples (m = 4, 5, 6, 7, or 8).


  • Differential coding: the two most significant bytes in each m-tuple are encoded in order to give some ruggedness to the signal.


  • QAM Mapper: the bit sequence is mapped into a base-band digital sequence of complex symbols. There are 5 allowed modulation
    Modulation

    In telecommunications, modulation is the process of varying a Periodic function waveform, i.e. a tone, in order to use that signal to convey a message, in a similar fashion as a musician may modulate the tone from a musical instrument by varying its volume, timing and Pitch ....
     modes: 16-QAM, 32-QAM, 64-QAM, 128-QAM, 256-QAM.


  • Base-band shaping: the QAM signal is filtered with a raised-cosine shaped filter, in order to remove mutual signal interference at the receiving side.


  • DAC and front-end: the digital signal is transformed into an analog signal, with a digital-to-analog converter
    Digital-to-analog converter

    In electronics, a digital-to-analog converter is a device for converting a digital code to an analog signal .An analog-to-digital converter performs the reverse operation....
     (DAC), and then modulated to radio frequency by the RF
    RF

    Rf or RF is an abbreviation for:* ** Radiative forcing, is an IPCC unit that nominates the global, annual average of radiative imbalance in net heating of the Earth's lower atmosphere as a result of human activities since the beginning of the industrial era....
     front-end
    Front-end and back-end

    Front-end and back-end are generalized terms that refer to the initial and the end stages of a process. The front-end is responsible for collecting input in various forms from the user and processing it to conform to a specification the back-end can use....
    .


Dvbc Eng Rates

Technical description of the receiver

The receiving STB adopts techniques which are dual to those ones used in the transmission.

  • Front-end and ADC: the analog RF signal is converted to base-band and transformed into a digital signal, using an analog-to-digital converter
    Analog-to-digital converter

    An analog-to-digital converter is a device which converts continuous signal to Discrete signal digital numbers. The reverse operation is performed by a digital-to-analog converter ....
     (ADC).


  • QAM Demodulation
  • Equalization
  • Differential decoding
  • Outer deinterleaving
  • Outer decoding
  • MUX adaptation
  • MPEG-2 demultiplexing and source decoding
  • Programmable Transport Stream


See also

  • Digital Video Broadcasting (DVB)
  • DMB
    Digital Multimedia Broadcasting

    Digital Multimedia Broadcasting is a South Korean technology used in digital radio transmission system for sending multimedia to mobile devices such as mobile phones....
     (Digital Multimedia Broadcasting
    Digital Multimedia Broadcasting

    Digital Multimedia Broadcasting is a South Korean technology used in digital radio transmission system for sending multimedia to mobile devices such as mobile phones....
    )
  • Digital television
    Digital television

    Digital television is the sending and receiving of moving images and sound by Discrete signal signals, in contrast to the Analog television used by analog TV....
     (DTV)
  • Digital television in Europe
    Digital television in Europe

    Refer to individual countries wikis for more information...
  • ATSC Standards
  • Redesign project, project set up by cable operators, equipment manufacturers, and research organisations


External links