In 1994, the world's first digital satellite TV services were launched in Thailand and South Africa. They utilized the newly developed Digital Video Broadcasting Satellite (DVB-S) system.
Over time, DVB-S became the most popular system for delivering digital TV broadcasts. Technology has advanced and spread tremendously since then, which lead to an increased need for advances to the DVB-S system. Thus, the DVB-S2 and DVB-S2X systems were born!
Let's take a look at both DVB-S2 and DVB-S2X and the main differences between them.
One of the biggest reasons for the second generation of digital video broadcasting was to enable the ability for the commercial launch of HDTV services. More specifically, some major benefits of DVB-S2 compared to DVB-S include
- Low Density Parity Check (LDPC) Forward Error Correction
- Variable Code Modulation (VCM)
- Adaptive Code Modulation (ACM)
- Enhanced Modulation Schemes up to 32 APSK
- Support for MPEG-2 TS Based Systems and MPEG-4 Audio-video streams.
DVB-S2 is able to achieve about a 30% increase in spectral performance compared to the original DVB-S. This allows for an increase in bit rate over the same DVB-S frequency bandwidth. In fact, it comes close to the Shannon Limit, the theoretical maximum information transfer rate in a channel for a given noise level.
DVB-S2 was formally published as an ETSI standard in 2005. Since then, there are now a number of major satellite broadcasters in both Europe and the USA that adopted the service.
DVB-S2 is still evolving with our constantly changing technology. In 2012, the DVB Project approved a new version of the specification that adds the reception of wideband signals (for example 200 MHz or 500 MHz). Upgrades and enhancements are still being made to the service.
The DVB-S2X system is not necessarily another model up of the DVB-S2, but an extension. The DVB-S2X was specified in the mid 2000s and provides additional technologies and features for the core applications of the DVB-S2. Applications include Direct to Home (DTH), Contribution, VSAT, and DSNG. It also covers an extended operating range with a focus on providing to emerging markets such as cellular devices and 5G.
DVB-S2X supports very low C/N down to -10 dB for mobile applications such as marine, aerospace, trains, etc. Like DVB-S2, DVB-S2X uses LDPC Forward Error Correction schemes and BCH FEC as an outer code.
DVB-S2X adds additional features and technologies such as
- More granularity of modulation and coding modes
- Smaller filter roll-off options of 5%, 10%, 20%, and 35%
- New constellation options for linear and non-linear channels
- Channel Bonding up to 3 channels
- More scrambling options for critical co-channel interference situations
- Very low SNR operation supporting C/N of down to -10dB
- Super Frame option
Technology upgrades and improvements also enable DVB-S2X to use smaller antennas and future broadband interactive networks for VSAT applications (intra-system interference mitigation, beam-hopping, and multi-format transmissions).
What other advances to DVB-S systems will need to be made in the near future with upcoming advances in technology? Comment your thoughts below!