Calibration of satellite beamforming channels
First Claim
1. A system, comprising:
- one or more input ports;
a plurality of output ports;
one or more beamforming circuits connected to the one or more input ports and the plurality of output ports, configured to receive signals from the one or more input ports and generate therefrom a plurality of output signals, the output signals configured to form a beam when transmitted from a corresponding plurality of the output ports; and
one or more calibration circuits connected to the beamforming circuits, the calibration circuits configured to generate a calibration signal and inject the calibration signal into the beamforming circuits concurrently with the beamforming circuits receiving from a first input port a user signal and generating therefrom output signals, the calibration signal being a spread spectrum signal with a power level lower than a noise floor of the user signal, the one or more calibration circuits further configured to receive the injected calibration signal after propagation through a portion of the beamforming circuits and, based on a comparison of the injected calibration signal to the calibration signal after propagating through the portion of the beamforming circuit, performing a calibration operation on the beamforming circuits.
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Accused Products
Abstract
Beamforming channels of a satellite are calibrated using a low power, spread spectrum calibration signal. The power of the calibration signal is below the noise level of a user signal in an active channel, allowing channels to be calibrated while active. When calibrating the transmit side circuitry, a two-stage calibration can be used, first calibrating the output hybrid matrix, then calibrating the whole of the transmit side. To improve performance, the dwell time spend calibrating a channel can be based on the power of the user signal in the channel. A transmit probe can be used to inject a calibration signal into the receive antennae and a receive probe can be used to extract the calibration signal from the transmit antennae. To reduce frequency of calibrations, the calibrations can be based on path-to-path differences.
26 Citations
20 Claims
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1. A system, comprising:
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one or more input ports; a plurality of output ports; one or more beamforming circuits connected to the one or more input ports and the plurality of output ports, configured to receive signals from the one or more input ports and generate therefrom a plurality of output signals, the output signals configured to form a beam when transmitted from a corresponding plurality of the output ports; and one or more calibration circuits connected to the beamforming circuits, the calibration circuits configured to generate a calibration signal and inject the calibration signal into the beamforming circuits concurrently with the beamforming circuits receiving from a first input port a user signal and generating therefrom output signals, the calibration signal being a spread spectrum signal with a power level lower than a noise floor of the user signal, the one or more calibration circuits further configured to receive the injected calibration signal after propagation through a portion of the beamforming circuits and, based on a comparison of the injected calibration signal to the calibration signal after propagating through the portion of the beamforming circuit, performing a calibration operation on the beamforming circuits. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A satellite, comprising:
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a plurality of receive antennae; a plurality of transmit antennae; one or more output signal generating circuits connected to the receive antennae and the transmit antennae, configured to receive signals from the receive antennae and generate therefrom output signals for the transmit antennae, the output signals configured to form a beam when transmitted from a corresponding plurality of the transmit antennae; and one or more calibration circuits connected to the output signal generating circuits, the calibration circuits configured to generate a calibration signal and inject the calibration signal into the output signal generating circuits concurrently with the output signal generating circuits receiving from the input antennae a user signal and generating therefrom output signals, the calibration signal being a spread spectrum signal with a power level lower than a noise floor of the user signal, the one or more calibration circuits further configured to receive the injected calibration signal after propagating through a portion of the output signal generating circuits and, based on a comparison of the injected calibration signal to the calibration signal after propagating through the portion of the output signal generating circuits, performing a calibration operation on the output signal generating circuits, wherein the output signal generating circuits are beamforming circuits. - View Dependent Claims (10, 11, 12, 13, 14)
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15. A method, comprising:
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receiving a user signal at a receive antenna of a satellite; transmitting a plurality output signals from a plurality transmit antenna; generating by one or more beamforming circuits a plurality of output signals from the user signal, the output signals configured to form a beam when transmitted from the plurality transmit antenna; and concurrently with generating the plurality of output signals, performing a calibration operation on the one or more beamforming circuits, the calibration operation including; generating a spread spectrum calibration signal having a power level lower than a noise floor of the user signal; injecting the calibration signal into the one or more beamforming circuits; receiving the injected calibration signal after propagating through a portion of the beamforming circuits; performing a comparison of the injected calibration signal to the calibration signal after propagating through the portion of the beamforming circuit; and performing a calibration operation on the beamforming circuits based on the comparison. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification