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The First DVB-T2 Single Frequency Network (SFN) in Vietnam


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The First DVB-T2 Single Frequency Network (SFN) in Vietnam


by Dr Ngo Thai Tri, MS Nguyen Chien Thang, Hoang Thanh Tung Vietnanm


1. About DVB-T2


DVB-T is a digital terrestrial television standard which has been successfully implemented in many countries world-wide. First released in 1995, it has been adopted by more than one hundred countries and regions. In parallel with implementing the DVB-T standard, researchers made continuous efforts to improve digital transmission and broadcasting technology. Moreover, the demand for broadcasting frequency spectrum has been increasing raised the question of how to maximise frequency spectrum efficiency. In response, the DVB Project developed the second-generation digital terrestrial television (DVB-T2) standard. The specification, first published by the DVB Project in June 2008 was standardised by the European Telecommunication Standards Institute (ETSI) in September 2009. Implementation and product development using this new standard has already begun.


The possibility of increasing the capacity within a digital terrestrial television (DTT) multiplex is one of the key benefits of the DVB-T2 standard. In comparison with the earlier DVB-T standard, the second-generation standard, DVB-T2, provides an increase in capacity of at least 30% in equivalent reception conditions, using existing receiving antennas. In particular the DVB-T2 specification allows for the possibility of maximising performance in SFN applications. Compared with the DVB-T standard, new carrier modes have been added to improve the performance of SFNs and increase the symbol period.


Many countries, such as the United Kingdom, Italy, Sweden, Finland,…have adopted and successfully deployed DTT systems according to the criteria of the DVB-T2 standard. Following the above trend, Audio Visual Global JSC., (AVG Vietnam) has conducted tests and deployed a DTT broadcasting network using the DVB-T2 standard for SFN technology, which helps save frequency resource.


2. SFN design based on DVB-T2 Standard


2.1 SFN Technology


When setting up SFN, all transmitters in network transmit on the same channel, which is convenient for planning and saving frequency resource.


Three requirements for all transmitters in one SFN as below:


(1) The same transport stream (TS) (2) The same frequency (3) At the same time


To set up and adjust the synchronisation between the transmitters in SFN network, AVG use T2 Gateway blocks, GPS receiver to transmit the synchronous signal to transmitters through 1pps and 10 MHz signal from the satellite.


Figure 1: General Structure of over-air distribution of the T2-MIP to a SFN Sub-network Source: ETSI TS 102 773 V1.2.1 (2010-12)


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