Measurements of the Time Statistics of FMTV Spectra and Tv Interference Into FDM/Fm Carriers

Abstract

When computing the amount of interference from FMTV signals in satellite systems, it is customary to consider that the only effective TV modulation is the energy dispersal signal (EDS). This leads to a sufficient but highly conservative system design, since for most of the time the wanted demodulated signal may experience interference levels well below that computed using this approach. If the time statistics of the interference can be determined through measurement, then a grade‐of‐service approach can be taken in which interference can be guaranteed not to exceed a certain level for more than a prescribed fraction of the time. This approach will lead to more efficient use of orbit/spectrum resources as a result of the implementation of less conservative system designs. This paper presents a simulation approach used to ‘measure’ FMTV power spectra with and without EDS and the corresponding interference powers into the basebands of FDM/FM carriers. Time statistics in the form of FMTV spectral masks and FDM baseband interference power time distributions have been derived from the measured data of 1000 off‐air TV frames for co‐channel TV and standard FDM/FM carrier sets (12 to 1200 channels) deployed by INTELSAT. Sample results are given.