Characteristics of fading and fade countermeasures on a satellite-Earth link operating in an equatorial climate. with reference to broadcast applications

摘要

Measurements of 12 GHz attenuation, using a satellite beacon receiver, are reported for a station in Malaysia, in one of the most extreme climates with regard to rainfall intensity. The data are analysed. with particular reference to broadcast applications, including data broadcast, multi-media, and time-repeated video applications. Of particular interest is the performance of time diversity, which is characterised with delays between 1 and 60 min. An empirical relationship is proposed, enabling time-diversity gain to be determined as a function of delay. Consideration is given to diurnal variations of attenuation and the additional margin necessary if good performance is to be maintained in peak broadcast hours. The relationship between the annual cumulative statistics of attenuation and the worst month attenuation is also investigated. In such an equatorial climate, with frequent fading throughout the year, it is seen that the worst-month criterion may not be such a useful or necessary measure as in other climates. The problem of prediction of attenuation is addressed using locally collected rain intensity data, and it is seen that further knowledge of rain structure is necessary to improve the quality of predictions.