ACCESSING CP CHANNELS WITH LP TERMINALS VIA WAVEFRONT MULTIPLEXING

摘要

Presented are methods that utilize wavefront multiplexing for enabling linearly-polarized terminals to access circularly-polarized satellite transponders. The methods disclosed herein feature (1) polarization formation capability that renders transmitted signal conditioned on circularly-polarized channels through multiple linearly-polarized feeds, and (2) polarization-conversion capability that compensate path differentials introduced by electromagnetic wave propagation channels. Data streams to be transmitted are pre-processed by a wavefront multiplexer into multiple wavefront components in linear polarization formats, where signals from respective data streams are replicated into linearly-polarized sub-channels. These replicated data streams are linked via a unique complex weighting vector (amplitude and phase or their equivalents), or “wavefront”, which are also linked by various spatially independent wavefronts. Additionally, a probing signal is sent on the transmitting side and linked via some of the independent wavefronts. Aggregated signals in linearly-polarized sub-channels are unique linear combinations of all input data streams. Aggregated signals in turn appear in circularly-polarized formats and propagate through circularly-polarized channels including circularly-polarized satellite transponders and a circularly-polarized teleport on the receiving side. Correlation between the circularly-polarized signal and the probing signal is sent back to the transmitting side that drives the polarization-conversion function toward the optimal state such that this correlation is lower than a pre-defined level. Accordingly, an optimally configured satellite communication system either (1) enables the linearly-polarized terminal on the transmitting side to access right-hand circularly-polarized satellite transponder without interfering the left-hand circularly-polarized satellite transponder, or (2) enables the linearly-polarized terminal on the transmitting side to access left-hand circularly-polarized satellite transponder without interfering the right-hand circularly-polarized satellite transponder.

主权项

1. Methods for a communications system comprising
a linearly-polarized (LP) transmitting terminal transmitting a horizontally polarized (HP) signal through a HP port and a vertically polarized (VP) signal through a VP port at a common frequency slot through circularly-polarized (CP) channels; a polarization-conversion element at said transmitting LP terminal modifying the relative amplitude and phase of said HP and said VP signals; and a circularly-polarized (CP) feedback unit receiving feedback signals from said CP channels.