RESULTADO DE LOS TESTS DE TV DIGITAL TERRESTRE, BRASIL AÑO 2000

Chapter VI – Conclusions
Considering:
• That the COFDM modulation presents a better performance in severe
multipath situations verified in areas densely peopled;
• That the COFDM modulation allows the implementation of transmission
in High Definition with adequate robustness;
• That there are solutions in the COFDM modulations that out perform the 8VSB modulation in the impulsive noise immunity;
• That only the COFDM modulation allowed a 100% reception of the spots within the 10 Km radius. This radius was a function of the used ERP; bigger ERPs will correspond to bigger radiuses with 100% reception;
• That the results of the lab tests suggest that only the COFDM modulation allows the reception in areas not reached by any system, through the use of Single Frequency Networks;
• That the 4dB advantage in the signal-noise ratio of the 8VSB modulation did not turn out to cause better coverage;
• That the disadvantageous results of the relation between the peak power and the average power have a low relevance, once they are costly only for the broadcasters, not the population;
• That the noted disadvantage observed in the COFDM modulation to the
protection relation for adjacent channels can be eliminated by introducing filters with better rejection characteristics in the receivers;
• That all the results of co-channel interference are not significant to the
planning of any of the tested modulations;
• That when a point of reflection is moving, the COFDM modulation shows better performance enabling even mobile reception;
• That the 8VSB receivers developed during the 2nd semester of 1999 and made available to the tests, until now, in despite of the use of
sophisticated equalizing techinique, did not show real improvements in
practical situations;
• That the COFDM modulation presents flexibility in the solving of
coverage problems;
• The objective of optimizing the reception, duplicating or improving the
current analog systems coverage ;
• That it is indispensable the use of a modulation that maximize the free off air reception;

We conclude that the COFDM modulation, besides being technically superior, is more adequate to the Brazilian conditions than the 8VSB modulation and, therefore, we suggest to Anatel that it determines that the Digital Television system to be adopted in Brazil must use the COFDM modulation.
We can observe that the disadvantages shown by the COFDM modulation systems are solvable, even though it implies additional cost to the broadcasters.
However, the mentioned disadvantages shown by the systems with 8VSB
modulation picture the boundaries inherent to the modulation itself. Only the consumer, who will need reception systems – antenna and receiver – more sophisticated, in the same proportion that his location may require, shoulders the onus of the flaws in the 8VSB modulation. On the other hand, only the broadcaster who, in certain situations, will have to implement transmission systems morepowerful or sophisticated shoulders the onus of the difficulties in the COFDM
modulation, all solvable.
Among the possible systems that use the COFDM modulation, we believe that it is still necessary the accomplishment of further and complimentary tests, besides the market issue consideration, such as the evaluation of the impact that adopting on of the available systems will have on the national industry, and the timing of commercial availability of each system, so to make the final decision on
the standard to be considered.
Therefore, we will use the additional period that Anatel has conceded, that will be until the end of April, so we can develop the activities, the experiments and the necessary studies to reach a final positioning about which Digital TV system we consider more adequate to be adopted in Brazil