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0486-2013

DTT recption and fading efects in the coast

Description: 

The phenomenon consisting in the power variation of TV signals due to the alteration of the propagation conditions in any section other path between the transmitter and reception site is called "fading " This is a typical effect in the coast where ter1lJEmture, humidity and tides generate different propagation conditions in terrestrial and marine sections, especially during the summer due to the higher evaporation in the trajectories over the water
Adding the overlapping of signals coming from multiple transmitters (multipath effect), the quality and stability of the signal become very poor. This is the reason why it is very importantt to find solutions that minimize both effects, The report on which is based this article shows the facing md echoes phenomena suffered by the population of San Pedro de Alcántara Marbella (Over 700 peope in summertime) that receive 1'1 signal from San Roque, Marbella, Mijas and Sierra Lújar transmitters, almost aligned and transmitting in the same frequencies (SFN network), The figures below show the day evolution of the signal in the location marked in red, samples of one SFN channel taken approximately every hour, from 10 am. The irregular behavior of the signal coming from the different transmitters is cleat1y shown.

 

 


The figures show how when nights falls, the temperatures drop and the signal recovers its stability, However the better propagation condition, increase the multipath (echoes) effect and the receivers continue having seriously problems, the DATHD Boss, designed to reduce the impact of echoes and to maintain the output signal stable independently from the input variations, is the antenna with the best features to minimize both effects.
Measurements
The measurements taken in the 

 

test site with a an antenna well positioned in the market, and the DAT HD BOSS with the BOSS Tech not activated and activated, were:



If the results with the BOSS Tech not activated are already good, with its activation the signal quality is clearly improved.
Power levels equalization,
Stable and strong signal
MER improvement.
Echoes discrimination improvement. The impact other signals from San Roque dissapears
Conclusions
Measurements made with the DATHD BOSS show its high capacity to minimize the impact of echoes and to absorb large fluctuations caused by fading, thereby improving signal quality significantly.

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