DVB-S2 is version 2 of the satellite delivered Digital Video Broadcast (DVB) standard. Introduced in 2003, DVB-S2 offers an increased data rate compared to the preceding standard DVB-S. This increased power and spectral efficiency, in combination of more efficient compression techniques such as MPEG-4, facilitated the takeup of satellite-delivered HDTV.
Television viewers with older set top boxes cannot receive the new standard and this means that broadcasters often transmit the same content in standard definition (SD) and High Definition (HD). This is known as simulcasting. However, transmitting the same thing twice is not optimal from the broadcasters’ point of view due to the need for more satellite capacity.
DVB-S2 Variable Coding and Modulation (VCM) mode in combination with scalable video coding (SVC) may provide an answer, as proven in this series of experiments. In this scenario, a base layer consisting of the SD video stream is complemented with delta information that allows the HD picture to be formed. The information transmitted in the SD layer is re-used. Also the SD layer can be given stronger protection against fade events, thanks to the combination of SVC and DVB-S2 VCM technologies.
This means that transmissions can elegantly continue, albeit with a lower resolution, even during a heavy rainfall. For the viewer that means there is no longer the chance of missing the best part of a film or the winning goal of a sporting match. It also means that more data can be transmitted with the same satellite power and bandwidth, resulting in even more services for users at a more affordable cost.
Although this technique could be valuable with today’s Ku-band transmissions which covers the frequencies of 10.7 to 12.75GHz, it will become even more important in the future. Due to the frequency congestion at Ku-band and the need for more bandwidth, the use of satellite broadcasting at Ka-band, which covers the frequencies of 20 to 30 GHz, may become more common. ESA is also investigating the use of even higher frequencies at the Q/V band. A link to this project is located in the column to the right. The problem of adverse weather conditions at these frequencies can be diminished according to the test results.
These activities have been performed by EADS Astrium (Toulouse, France) and Fraunhofer HHI (Berlin, Germany). To view the presentations which outline all of the tests and results conducted in the ARTES 5 DVB-S2 Experiment project, and for more information, visit the links in the column to the right.
