Patent
Uplink cross-polarization interference canceller using correlation calculator and stepwise tracking controller
TLDR
In this article, a correlation calculator is used to estimate uplink cross-polarization interference components from the downlink cross polarization cancelling control signals and adjust the angle settings of the 90° and 180° phase shifters with the estimated components.Abstract:
In a satellite communications system, a rotatable 90° phase shifter and a rotatable 180° phase shifter introduce variable phase shifts to a single pilot signal, which is transmitted to the satellite. Downlink cross-polarization interference cancelling control signals are derived from a beacon signal received from the satellite. A pulse sequence is generated to modulate the amplitude of a carrier to produce an ASK signal as the pilot signal. A correlation calculator provides coarse mode interference cancellation by estimating uplink cross-polarization interference components from the downlink cross-polarization cancelling control signals and adjusting the angle settings of the 90° and 180° phase shifters with the estimated components. The pilot signal is transmitted back to the earth and synchronously detected with the pulse sequence to derive a DC signal which represents an uplink cross-polarization interference. A stepwise tracking controller provides fine mode interference cancellation by stepwisely varying the 90° and 180° phase shifters by predetermined amounts an detecting previous and recent values of the synchronously detected DC signal resulting from the stepwise variations, and repeating the stepwise variations until a difference between the previous and recent values is substantially reduced to a minimum.read more
Citations
More filters
Patent
Methods of ground based beamforming and on-board frequency translation and related systems
TL;DR: In this paper, the authors provide a method to operate a communications system including a satellite and a satellite gateway over a feeder link frequency band for communication of information between the satellite gateway and the satellite.
Patent
Systems and methods for improved high capacity in wireless communication systems
Paul A. Kennard,Sergio Licardie +1 more
TL;DR: In this article, an N-plexer is used to provide the first and second diversity received signals to a first cable in communication with a first modem, where the first cable is configured to receive the first-and second-diversity received signals.
Patent
Method and apparatus for locating and tracking a qpsk carrier
TL;DR: In this article, the tuner is swept in a search for the QPSK carrier at the Power On Reset mode of the receiver and a low OOS signal is sought.
Patent
Systems and methods for signal frequency division in wireless communication systems
TL;DR: In this article, the authors considered a system with at least one antenna for receiving a first receive signal having a first signal diversity property and a second receive signal with a second signal diversity.
Patent
Satellite uplink power control
TL;DR: In this article, a method and system for Uplink power control in a satellite communication system comprising a geostationary satellite communicating with a gateway station and at least two other gateway stations is described.
References
More filters
Patent
System for compensating cross-polarized waves to attenuate crosstalk
Shoji Soma,Ikuro Sato +1 more
TL;DR: In this paper, the phase and amplitude adjustment of variable phase shifter circuits and variable attenuator circuits are adjusted by the control circuits in accordance with the values of the received pilot signals.
Patent
Digital demodulation system having independently operating cross-polarization cancellers
TL;DR: In this article, a digital radio transmission in which first and second-channel radio frequency digital signals are transmitted respectively on othogonally polarized radiowaves and the first-and second-IF signals are derived respectively from the first and the second-and third-channel RF signals are proportioned in response to a control signal and subtractively combined with the first IF signal.
Patent
System for compensating for cross polarization coupling
TL;DR: In this paper, the same polarized wave components of the two signals received by a communication satellite are sent back to the earth station, so that the sent back signal is received by the ground station.
Patent
Cross polarization compensation system
TL;DR: In this article, a cross polarization compensation system is proposed, in which an input elliptically polarized wave is converted, by a first rotatable differential phase shifter having a phase shift of 90° or less than 90°, into an elliptically polarised wave defined by |α|=|cot.sup.-1 γ| (where α is the tilt angle of an ellipse indicative of the elliptical polarized wave relative to a predetermined reference direction and γ is the axial ratio for the ellipsse), and then the phase delay or advance plane of