Satellite beam-pointing error correction in digital beam-forming architecture
First Claim
1. A method for adjusting the pointing direction of a beam provided by an antenna system of a spacecraft, the spacecraft forming part of a system that includes ground stations communicating with the antenna system of the spacecraft using uplink signals and downlink signals, each in a respective frequency channel, the antenna system including a receive antenna having a plurality of antenna elements arranged in an array, each element providing a respective antenna element signal and at least one of said uplink signals including a beacon signal, the method comprising:
- digitising each said antenna element signal from said receive antenna, and processing each digitised antenna element signal to separate uplink signal components in respective frequency channels present in the element signal;
digitally weighting, with respective beam-pointing error weight values, components of said beacon signal present in at least some of the receive antenna element signals, and assessing such weighted beacon signal components to derive a beam-pointing error signal; and
employing said error signal to adjust the pointing direction of at least one communications signal beam provided by said antenna system.
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Accused Products
Abstract
A digital method of determining and correcting beam-pointing for a communications spacecraft that has a digital beam-forming architecture for defining multiple spot transmit and receive beams, the antenna system of the spacecraft including a receive antenna (DRA, AFR) having antenna elements providing respective antenna element signals, and wherein at least one of the uplink signals to the spacecraft includes a beacon signal, and wherein the method comprises digitally weighting components of said beacon signal present in antenna element signals, combining such weighted beacon signal components such as to derive beam-pointing error signals, and employing the error signals to adjust beam-forming weight values of the receive antenna, in order to adjust the pointing direction of at least one signal beam. The digital weights for the beacon signal define difference radiation patterns for x, y axes of the antenna which vary rapidly in a range corresponding to the pointing errors most commonly occurring.
19 Citations
43 Claims
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1. A method for adjusting the pointing direction of a beam provided by an antenna system of a spacecraft, the spacecraft forming part of a system that includes ground stations communicating with the antenna system of the spacecraft using uplink signals and downlink signals, each in a respective frequency channel, the antenna system including a receive antenna having a plurality of antenna elements arranged in an array, each element providing a respective antenna element signal and at least one of said uplink signals including a beacon signal, the method comprising:
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digitising each said antenna element signal from said receive antenna, and processing each digitised antenna element signal to separate uplink signal components in respective frequency channels present in the element signal; digitally weighting, with respective beam-pointing error weight values, components of said beacon signal present in at least some of the receive antenna element signals, and assessing such weighted beacon signal components to derive a beam-pointing error signal; and employing said error signal to adjust the pointing direction of at least one communications signal beam provided by said antenna system. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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23. Apparatus for a spacecraft, comprising:
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a receive antenna including a plurality of antenna elements arranged in an array, each antenna element providing a respective antenna element signal in response to received uplink signals in respective frequency channels; digital processing means for digitising each said antenna element signal and for separating uplink signal components in respective frequency channels present in each said antenna element signal; beam-pointing error weighting means for digitally weighting components of a beacon signal comprising one of said uplink signals in a respective frequency channel, and being present in at least some of the antenna element signals, with respective beam-pointing error weights; assessment means for assessing the weighted beacon signal components to derive a beam-pointing error signal; and adjustment means for employing said error signal to adjust the pointing direction of at least one communications signal beam provided by the spacecraft. - View Dependent Claims (24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42)
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43. Apparatus for a spacecraft, comprising:
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a receive antenna including a plurality of antenna elements arranged in an array, each antenna element providing a respective antenna element signal in response to received uplink signals in respective frequency channels; an uplink signal synthesiser for digitising each antenna element signal and separating uplink signal components in respective frequency channels present in each antenna element signal; a beacon direction assessment processor responsive to a beacon signal comprising one of said uplink signals in a respective frequency channel and configured to digitally weight components of said beacon signal present in at least some of the antenna element signals with respective beam-pointing error weights, and assess the weighted beacon signal components to derive a beam-pointing error signal; and a controller for employing said error signal to adjust the pointing direction of at least one communications signal beam provided by the spacecraft.
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Specification