Study of the required crosspolar protection ratio in G-PAL TV FM satellite transmissions planning

摘要

A study including simulation and a measurement campaign using live TV broadcast satellite signals and receiving commercial equipment has been carried out to investigate the required cross-polar protection ratio at the terrestrial receiving antenna for satellite transmission planning. This experiment provides useful and realistic results for efficient channel allocation in the spectrum band of broadcast satellite systems. Among them is the frequency offset required between cross-polar channels, depending on the cross-polar rejection at the receiving antenna, for a certain degree of video signal impairment due to the cross-polar channel interference effect, and taking into account the noise contribution to the signal. A worst case in frequency offset value, i.e., larger subjective impairment of the picture at equal carrier to noise ratio (CNR), has been detected around 5 MHz (near the chroma carrier in G-PAL system 4.43 MHz) only for high values of CNR. Different subjective degradation of the image due to cross-polar channel interference and noise has been observed, and their particular contributions to impairment have been evaluated.