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Background

Variable Coding and Modulation (VCM) and Adaptive Coding and Modulation (ACM) are techniques that are strongly associated with the DVB-S2 standard. VCM can be used to provide different levels of error protection to different components within the service. It does this by allowing different combinations of modulation and FEC rate to be applied to different parts of the data stream. ACM extends VCM by providing a feedback path from the receiver to the transmitter to allow the level of error protection to be varied dynamically in accordance with varying propagation conditions. Claims of performance improvements exceeding 100% have been made for ACM in terms of satellite capacity gain. (continue reading…)

TBS6925 test report from TELE-satellite magazine 1201

With the change from DVB-S to DVBS2, a more efficient method was created that permits more channels to be carried over one and the same transponder. This increase in efficiency is due in large part to the significant improvement in error correction so that fewer error correction bits need to be transmitted. From a mathematical point of view the increase in efficiency compared to DVB-S is roughly 30%, a value that in reality isn’t quite reached, but it is definitely showing potential. (continue reading…)

DVB-S to DVB-S2 Migration

DVB-S defines support for one modulation format (QPSK) and five FEC codes 1/2, 2/3, 3/4, 5/6 and 7/8, but DVB-S2 defines support for 28 combinations of modulation and codes (MODCODs) ranging from 1/4 QPSK to 9/10 32-APSK. (continue reading…)

TBS 6925 is known as a professional PCI-E DVB-S2 TV Tuner Card, featuring VCM, CCM and ACM mode support and Multiple Transport Stream Receiving.

Here are the procedures of how to use the TSRecorder tool to receive DVB-S2 VCM, CCM and ACM signals. (continue reading…)

To watch satellite TV on your PC with XBMC and MythTV, you’ll need at least one satellite TV tuner card or a satellite provider that offers satellite IPTV access. That Linux TV card hardware doesn’t have to be installed on the same computer on which you want to watch HDTV. We’ll call the computer with the tuner hardware the backend. The computer used to view TV will be called the frontend. The backend and frontend can be one and the same machine. XBMC will be run on the frontend on linux (continue reading…)