SATELLITE BEAM-POINTING ERROR CORRECTION IN DIGITAL BEAM-FORMING ARCHITECTURE
2 Assignments
0 Petitions
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.
-
Citations
80 Claims
-
1-40. -40. (canceled)
-
41. A method of beam-forming for an antenna of a spacecraft, the spacecraft forming part of a system that includes ground stations communicating with an antenna system of the spacecraft by means of uplink signals and downlink signals, each in a respective frequency channel, which antenna system includes a receive antenna having a plurality of antenna elements arranged in an array, each element providing a respective antenna element signal, the method comprising:
-
digitising each said antenna element signal, 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-forming weight values, said uplink signal components in at least one frequency channel, and combining the weighted components to synthesise the uplink signal in said one frequency channel;
wherein at least one of said uplink signals includes a beacon signal, and wherein the method further comprises;digitally weighting, with respective beam-pointing error weight values, components of said beacon signal present in at least some of the antenna element signals, and assessing such weighted beacon signal components such as 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 (43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 59, 60, 61)
-
-
42. A method of beam-forming for an antenna of a spacecraft, the spacecraft forming part of a system that includes ground stations communicating with an antenna system of the spacecraft by means of uplink signals and downlink signals, each in a respective frequency channel, which antenna system includes a receive antenna and a transmit antenna, each said antenna including a plurality of antenna elements arranged in an array, each element having an associated respective antenna element signal, the method comprising:
-
digitising each said 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, providing downlink signals in respective frequency channels and in digital form, which are selectively digitally weighted, with respective beam-forming weight values, to synthesise downlink antenna element signals for the antenna elements of said transmit antenna;
wherein at least one of said uplink signals includes a beacon signal, and wherein the method further comprises;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 such as 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 transmit antenna. - View Dependent Claims (58)
-
-
62. Apparatus for forming a beam of a spacecraft antenna, comprising:
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, uplink signal synthesis means including 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, and beam-forming weighting means for digitally weighting said uplink signal components in at least one frequency channel with respective beam-forming weight values, and combining means for combining such selected components to synthesise at least one uplink signal in a respective frequency channel;
beacon direction assessment means responsive to a beacon signal comprising one of said uplink signals in a respective frequency channel, and including beam-pointing error weighting means for digitally weighting components of said beacon signal present in at least some of the antenna element signals with respective beam-pointing error weights, and 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 (64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80)
-
63. Apparatus for forming a beam of a spacecraft antenna, comprising:
- a receive antenna and a transmit antenna, each antenna including a plurality of antenna elements arranged in an array, and each antenna element providing a respective antenna element signal in response to uplink/downlink signals in respective frequency channels, uplink signal synthesis means including digital processing means for digitising each receive antenna element signal, and for separating uplink signal components in respective frequency channels present in each said antenna element signal, downlink signal synthesis means including digital means for selectively forming downlink signals in respective frequency channels, and beam-forming weighting means for selectively digitally weighting downlink signals in respective frequency channels with respective beam-forming weight values, for providing antenna element signals to said transmit antenna;
beacon direction assessment means responsive to a beacon signal comprising one of said uplink signals in a respective frequency channel, and including beam-pointing error weighting means for digitally weighting components of said beacon signal present in at least some of the receive antenna element signals with respective beam-pointing error weights, and 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.
- a receive antenna and a transmit antenna, each antenna including a plurality of antenna elements arranged in an array, and each antenna element providing a respective antenna element signal in response to uplink/downlink signals in respective frequency channels, uplink signal synthesis means including digital processing means for digitising each receive antenna element signal, and for separating uplink signal components in respective frequency channels present in each said antenna element signal, downlink signal synthesis means including digital means for selectively forming downlink signals in respective frequency channels, and beam-forming weighting means for selectively digitally weighting downlink signals in respective frequency channels with respective beam-forming weight values, for providing antenna element signals to said transmit antenna;
Specification