SOURCEFORGE » RALF » 2014 ACM testing using channel emulation

h1. Overview

The DVB-S standard (Digital Video Broadcasting-Satellite) was released in its first version in 1995 and aimed at normalize the physical link characteristic and framing for satellite television. However, digital satellite transmission technologies have evolved considerably since this first publication as new coding and modulation schemes have been developed, permitting greater flexibility and more efficient use of capacity. Moreover, demands for new services such as HD television, interactive services, VoIP (voice over IP) or internet access have growth exponentially.

This context led to the definition of a new standard defining a new generic transport mechanism that can handle IP packets and MPEG-4 audio video streams. This standard was ratified by ETSI in 2005 and called DVB-S2. The table below summarizes the main differences between DVB-S and DVB-S2:

                                    tableau

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These new features result in a more efficient use of the bandwidth, more flexibility, 

More efficient use of bandwidth, more margin, more flexibility  less satellite cost, less amplifier power

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As DVB-S2 standard introduced a return channel (for ACM features for example), a standard has also been established to specify the characteristics of this channel: DVB-RCS (Return Channel via Satellite). 

A new optional extension of DVB-S2, called DVB-S2X, has just been standardized by DVB project in March 2014. It brings some improvements with, for examples:

    - Higher modulation Schemes (64/128/256 APSK)

    - Smaller Roll-off factors

    - Improved filtering leading to smaller carrier spacing