Co-channel and adjacent channel interference in actual terrestrial TV scenarios--Part I: field measurements

The results of an extensive study on analog PAL signals interfered with by digital DVB-T signals are presented in this paper. The research work covers field measurements, laboratory measurements, a theoretical evaluation of the interference problems, and even a national survey among TV installation companies. The main objective is the identification and explanation of the interference problems reported at several towns since the start of DVB-T broadcasting. This paper is organized in two parts. Part I includes the description of the field measurements, whereas the laboratory measurements and the poll results are described in Part II. It has been found that the frequency plan is part of the source of the interference problems, particularly in the case of co-channel interference. Another source for the problems is that different radiation elements are used, at the same site, for broadcasting DVB-T and analog TV signals. As it is stated in ETSI documents [1], the use of a different antenna dedicated to DVB-T may require ERP restrictions to protect existing analog services. The power ratios between digital and analog TV signals at the broadcasting station should be adjusted in order to meet the protection ratios at every point within the coverage area. The required power ratio would depend on the specific shape of the radiation pattern of each antenna. Finally, it has been found that an important part of the interference problems are due to the amplifiers of the Master Antenna Television (MATV) systems in buildings. The results of the laboratory tests and the theoretical analysis conducted to determine the increment of the protection ratio required by the presence of these amplifiers are presented in Part H of the paper. Index Terms--Adjacent-channel, co-channel, digital television, DVB-T, field measurement, interference.