DVB-S, DVB-S2, and DVB-S2X are all satellite transmission standards used for delivering digital TV content over satellite. A set-top box that supports these standards is required to receive and decode the digital signal from the satellite.
To understand DVB-S/DVB-S2/DVB-S2X or other generations of this technology, first of all, understand what is DVB. DVB stands for Digital Video Broadcasting which is a set of standards used by satellite, cable, and terrestrial broadcasting infrastructure. It has been made under DVB Project. Today the DVB Project includes more than 220 organizations from more than 29 countries around the world. The types of DVB-compatible digital broadcast and equipment widely available are distinguished by the DVB logo. DVB-S means Digital Video Broadcasting via Satellite. Here S stands for Satellite.
DVB uses a Conditional Access (CA) system to prevent external piracy. The CA system provides a security module that scrambles and encrypts data.
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DVB-S-:
DVB-S is the oldest of the three standards, and it is designed for standard-definition (SD) TV channels. DVB-S uses QPSK (Quadrature Phase Shift Keying) modulation and offers a maximum data rate of around 36 Mbps.
It is the first generation used in digital video broadcasting via satellite. In this, MPEG-2 TV channels were broadcast by satellite. Even now the use of this technology is seen occasionally. For example, DD Free Dish operated by Doordarshan still broadcasts satellite TV channels using this technology. MPEG-2 uses a lossy compression method which means that the digital signal sent to the television gets compressed and some data is lost in it. However, this lost data does not affect how the human eye sees a picture.
The two digital TV formats used by MPEG-2 compression are –
- Standard-definition television (SDTV)
- High-definition (HDTV)
DVB-S2-:
DVB-S2 is a newer and more advanced standard than DVB-S, designed for both standard and high-definition (HD) TV channels. DVB-S2 uses more advanced modulation schemes, such as 8PSK and 16APSK, to offer higher data rates than DVB-S. It also features improved error correction and channel coding, resulting in better performance and signal quality. DVB-S2 offers a maximum data rate of around 120 Mbps.
DVB-S2 evolved with the introduction of HDTV and the H. 264 (MPEG-4 AVC) video codecs. DVB-S2 has been widely adopted since its introduction in 2005 and DVB-S2X is expected to remain relevant for many years with additional features. We understand DVB-S2X a little more.
DVB-S2X – (Extension of DVB-S2) –
DVB-S2X is the latest satellite transmission standard, which was developed to provide even higher data rates and improved efficiency. DVB-S2X uses even more advanced modulation schemes, such as 64APSK and 256APSK, to offer higher data rates than DVB-S2. It also features more efficient channel bonding and improved error correction techniques. DVB-S2X offers a maximum data rate of around 500 Mbps.
It is an extended standard of the Second Generation of Digital Video Broadcasting-Satellite which enhances the support provided for DVB-S2 applications and improves the overall efficiency of communication through satellite links. DVB-S2 and DVB-S2X take advantage of recent hardware improvements and provide higher spectrum efficiency. DVB-S2 is able to achieve an increase of about 30% in spectral performance compared to the original DVB-S. With this, H.265 ie HEVC codec is used. Which has better picture quality and better compression.
DVB-S2X standard supports these additional features, it has developed many features such as –
- The greater granularity of modulation and code rates
- Smaller filter roll-off option for better bandwidth utilization
- Higher-order modulation schemes (64APSK, 128APSK, 256APSK)
- Very low signal-to-noise ratio (VLSNR) mode for mobile applications.
More recently, this DVB-S2X technology has been adopted in Freesat, a free satellite TV service operating in Sri Lanka. DVB-S2x satellite receiver is now also available in India.
When choosing an FTA (Free-to-Air) satellite set-top box, it’s important to consider the transmission standard used by the channels you plan to receive. If you plan to receive mostly SD channels, a set-top box that supports DVB-S would be sufficient. If you plan to receive a mix of SD and HD channels, a set-top box that supports DVB-S2 would be more appropriate. If you plan to receive a lot of HD channels or channels with high data rates, then a set-top box that supports DVB-S2X would be the best choice. It’s important to note that not all channels support the newer standards, so it’s best to check with your satellite provider before purchasing a set-top box.
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