Multi-channel satellite calibration
View Patent ↗This disclosure provides systems, methods and apparatus for multi-channel satellite calibration. In one aspect, a calibration system can provide a transmit calibration signal based on a reference calibration signal to a satellite. The satellite can transmit back a receive calibration signal that can be obtained by the calibration system. Sub-carriers of the receive calibration signal can be compared with sub-carriers of the reference signal to determine adjustments to transmission properties of antennas of the satellite.
1. A system comprising:
a calibration system communicatively coupled with a spacecraft, the calibration system configured to:
provide a transmit calibration signal to a plurality of channels of the spacecraft, the transmit calibration signal including a first plurality of sub-carrier signals corresponding to non-overlapping frequency components, each of the channels associated with a corresponding antenna;
obtain from the spacecraft, concurrently for all of the channels, a receive calibration signal including a second plurality of sub-carrier signals derived from the first plurality of sub-carrier signals;
determine a first set of differences between the first plurality of sub-carrier signals and the second plurality of sub-carrier signals; and
use the determined first set of differences to adjust one or more transmission properties of the antennas.
2. The system of claim 1 , wherein the one or more transmission properties include signal phases and amplitudes, and the system is further configured to calculate, using the determined first set of differences, equalization adjustments to the signal phases and amplitudes.
3. The system of claim 1 , wherein the one or more transmission properties include one or more of a signal phase, amplitude, group delay, or power level.
4. The system of claim 1 , wherein the first plurality of sub-carriers are derived from a third plurality of sub-carriers of a reference signal, the reference signal being an orthogonal frequency-division multiplexed (OFDM) signal.
5. The system of claim 4 , wherein the third plurality of sub-carriers are compared with the second plurality of sub-carriers to determine a second set of differences between the first plurality of sub-carriers and the second plurality of sub-carriers.
6. The system of claim 5 , wherein a first frequency range of the third plurality of sub-carriers is wider than a second frequency range of the second plurality of sub-carriers.
7. The system of claim 6 , wherein frequency components corresponding to the third plurality of sub-carriers are frequency shifted to generate the transmit calibration signal.
8. The system of claim 7 , wherein the frequency components corresponding to the third plurality of sub-carriers are frequency shifted to be within the frequency range of the second plurality of sub-carriers.
9. A calibration sub-system configured to calibrate transmission properties of one or more antennas of a spacecraft by providing an orthogonal frequency-division multiplexed (OFDM) transmit calibration signal having sub-carriers corresponding to non-overlapping frequency components to the spacecraft, and receiving an OFDM receive calibration signal from the spacecraft and having sub-carriers corresponding to non-overlapping frequency components, and providing an adjustment signal representing adjustments to the transmission properties of the one or more antennas, the adjustments corresponding to changes to one or more of a phase, amplitude, group delay, or power level of signals provided by the one or more of the antennas based on a comparison of the sub-carriers of the transmit calibration signal with the sub-carriers of the receive calibration signal.
10. The calibration sub-system of claim 9 , wherein the adjustments correspond to equalization adjustments representing differences between the sub-carriers of the sub-carriers of the transmit calibration signal with the sub-carriers of the receive calibration signal.
11. The calibration sub-system of claim 9 , wherein the calibration sub-system system is further configured to generate a reference calibration signal, wherein the sub-carriers of the transmit calibration signal are based on sub-carriers of the reference signal, the reference signal also being an OFDM signal.
12. The calibration sub-system of claim 9 , wherein the adjustments are based on differences between the sub-carriers of the transmit calibration signal and the receive calibration signal are based on sub-carriers of a reference calibration signal used to generate the transmit calibration signal.
13. The calibration sub-system of claim 12 , wherein the sub-carriers of the reference signal are compared with the sub-carriers of the receive calibration signal to determine the differences between the sub-carriers of the transmit calibration signal and the receive calibration signal.
14. The calibration sub-system of claim 13 , wherein a frequency range of the sub-carriers of the reference calibration signal is wider than a frequency range of the sub-carriers of the receive calibration signal.
15. The calibration sub-system of claim 14 , wherein frequency components corresponding to the sub-carriers of the reference calibration signal are frequency shifted to generate the transmit calibration signal.
16. The calibration sub-system of claim 15 , wherein the frequency components corresponding to the sub-carriers of the reference calibration signal are frequency shifted to be within the frequency range of the sub-carriers of the receive calibration signal.
17. A method comprising:
providing, by a calibration system, a transmit calibration signal having sub-carriers with non-overlapping frequency components;
receiving, by the calibration system, a receive calibration signal having sub-carriers with non-overlapping frequency components from a spacecraft;
generating, by the calibration system, adjustment data representing differences between sub-carriers of the transmit calibration signal and the sub-carriers of the receive calibration signal; and
providing, by the calibration system, an adjustment signal providing the adjustment data to adjust transmission properties of one or more antennas of the spacecraft.
18. The method of claim 17 , wherein said adjusting the transmission properties includes changes to one or more of a phase, amplitude, group delay, or power level of signals provided by the one or more antennas.
19. The method of claim 17 , wherein the transmit calibration signal is based on a reference calibration signal having sub-carriers at a wider frequency range than the sub-carriers of the transmit calibration signal.
20. The method of claim 17 , wherein the transmit calibration signal is an orthogonal frequency-division multiplexed (OFDM) signal.