DVB-C stands for "Digital Video Broadcasting - Cable" and it is the DVB European consortium standard for the broadcast transmission of digital television over cable. This system transmits an MPEG-2 or MPEG-4 family digital audio/digital video stream, using a QAM modulation with channel coding. The standard was first published by the ETSI in 1994, and subsequently became the most widely used transmission system for digital cable television in Europe, Asia and South America. It is deployed worldwide in systems ranging from the larger cable television networks (CATV) down to smaller satellite master antenna TV (SMATV) systems.
With reference to the figure, a short description of the single processing blocks follows.
The receiving STB adopts techniques which are dual to those ones used in the transmission.
On February 18, 2008 it was announced that a new standard - DVB-C2 - would be developed during 2008, and a "Call for Technologies" was issued. Proposals including simulation programs and information on patent rights could be submitted until June 16, 2008.
"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)
By using state of the art coding and modulation techniques, DVB-C2 should offer greater than 30% higher spectrum efficiency under the same conditions, and the gains in downstream channel capacity will be greater than 60% for optimized HFC networks.
The final DVB-C2 specification was approved by the DVB Steering Board in April 2009.
DVB-C2 allows bitrates up to 83.1 Mbit/s on an 8 MHz channel bandwidth when using 4096-QAM modulation; future extensions will allow up to 97 Mbit/s and 110.8 Mbit/s per channel using 16384-QAM and 65536-AQAM modulation.
Modes and features of DVB-C2 in comparison to DVB-C:
|Input Interface||Single Transport Stream (TS)||Multiple Transport Stream and Generic Stream Encapsulation (GSE)|
|Modes||Constant Coding & Modulation||Variable Coding & Modulation and Adaptive Coding & Modulation|
|FEC||Reed Solomon (RS)||LDPC + BCH 1/2, 2/3, 3/4, 3/5, 4/5, 5/6, 6/7, 7/8, 8/9, 9/10|
|Modulation||Single Carrier QAM||absolute OFDM|
|Modulation Schemes||16- to 256-QAM||16- to 4096-QAM|
|Guard Interval||Not Applicable||1/64 or 1/128|
|Inverse Fast Fourier transform (IFFT) size||Not Applicable||4k|
|Interleaving||Bit-Interleaving||Bit- Time- and Frequency-Interleaving|
|Pilots||Not Applicable||Scattered and Continual Pilots|