Accurate Detection of Satellite Beacon Polarization States Using Cascaded Heterodyne Phase-Locked Loops

The use of orthogonal polarizations sharing the same frequency is attractive in satellite communications due to its efficiency in utilizing the spectrum. The main problem remaining to be solved is that of the various cross polarization effects which cause interference between the orthogonal channels. The technique using cascaded heterodyne phase-locked loops (PLLs) to accurately detect the phase as well as amplitude of both copolarized and cross-polarized satellite beacon carriers under poor carrier-to-noise ratio conditions is developed and presented in this paper. Such a technique is very useful not only in satellite beacon measurements and cross polarization experiments, but also in the implementation of cross polarization restoration networks currently developed for satellite communication systems.