A Polarization Control System for Satellite Communications with Multiple Uplinks

Orthogonal polarizations will be more and more widely used in satellite communications in the near future because of their efficiency in utilizing the spectrum, but the currently designed compensation control systems can compensate for signals coming from only one uplink station. This paper therefore discusses generally the control schemes feasible to solve the multiple Uplink problem, in which there are many stations transmitting uplink signals simultaneously. The general approach proposed is that for each uplink station two Compensators can be used to compensate for the uplink and, downlink separately. This will require the station to transmit its own pilot signals and receive them back from the satellite as the control reference. Two basic techniques can be used to realize this approach. The first, correlation technique, is based on the assumption that an obtainable correlation between uplink and downlink cross-polarizations exists, and tries to compensate for uplink and downlink separately using this correlation. The second, separate link technique, uses an additional pair of pilotsignals to obtain seiJarate control references and decouples the compensations of uplink and downlink. The discussions indicate that the separate downlink technique, whose design considerations and system performance are examined carefully is most attractive.

[1]  A. F. Culmone.  Polarization diversity with adaptive channel decoupling , 1975 .

[2]  T. Oguchi.  Attenuation and phase rotation of radio waves due to rain: Calculations at 19.3 and 34.8 GHz , 1973 .

[3]  S. Lin,et al.  An Occurrence of Very Heavy Rain on a 42-km Path , 1974, IEEE Trans. Commun..

[4]  P. A. Watson,et al.  Rainfall crosspolarisation of linearly and circularly polarised waves at microwave frequencies , 1972 .

[5]  A. J. Gianatasio,et al.  Spectrum-reuse by adaptive polarization separation , 1975 .

[6]  H. Kannowade.  An Automatic Control System for Compensating Cross-Polarization Coupling in Frequency-Reuse Communication Systems , 1976, IEEE Trans. Commun..

[7]  P. A. Watson,et al.  Rainfall corosspolarisation at microwave frequencies , 1973 .

[8]  T. S. Chu,et al.  B.S.T.J. brief: Rain-induced differential attenuation and differential phase shift at microwave frequencies , 1973 .

[9]  R. A. Semplak,et al.  The effect of rain on circular polarization at 18 GHz , 1973 .

[10]  M. Cross,et al.  Scattering of a plane electromagnetic wave by axisymmetric raindrops , 1974 .

[11]  R. A. Semplak,et al.  Dual frequency measurements of rain-induced microwave attenuation on a 2.6-kilometer propagation path , 1971 .

[12]  David T. Thomas.  Cross‐Polarization Distortion in Microwave Radio Transmission Due to Rain , 1971 .

[13]  W. Trachtman,et al.  Adaptive polarization control for satellite frequency reuse systems , 1975 .

[14]  R. Taur,et al.  Rain depolarization measurements on a satellite-earth propagation path at 4 GHz , 1975 .

[15]  M. Saunders,et al.  Cross polarization at 18 and 30 GHz due to rain , 1971 .

[16]  R. A. Semplak,et al.  Simultaneous measurements of depolarization by rain using linear and circular polarizations at 18 Ghz , 1974 .

[17]  T. Chu,et al.  B.S.T.J. Brief: Perturbation calculations of rain-induced differential attenuation and differential phase shift at microwave frequencies , 1973 .

[18]  T. Chu.  Restoring the orthogonality of two polarizations in Radio communication systems, II , 1971 .

[19]  T. Oguchi,et al.  Attenuation of electromagnetic wave due to rain with distorted raindrops,2. , 1964 .

[20]  T. S. Chu,et al.  Rain-induced cross-polarization at centimeter and millimeter wavelengths , 1974 .

[21]  R. A. Semplak,et al.  Measurements of rain‐induced polarization rotation at 30.9 GHz , 1974 .