High-power flexible-polarization in-orbit-calibration satellite payload
A system of architecture, apparatus and calibration method is invented for high-power flexible-polarization payload for satellite communications. The system comprises onboard phase-tracked apparatus, flexible polarization mechanism, and in-orbit calibration method. The power combining and polarization performance of the phase-tracked payload is monitored on ground by measuring the cross-polarization discrimination (XPD) and/or axial ratio (AR). The high performance over the life is achieved by optimization of the XPD or AR on ground and adjusting complex gain of the transponders. The high-power flexible-polarization in-orbit-calibration payload may be applied but not limited to UHF, L, S, C, X, Ku and Ka-band high power satellite systems.
1. A high-power flexible-polarization satellite payload system for satellite communications, the system comprising:
a centralized On-Board Processor (OBP) connecting to a transmit chain having a first and a second transmit paths and a receive chain having a first and a second receive paths, said first transmit and first receive paths connecting to a first transmit/receive duplexer, said second transmit and second receive paths connecting to a second transmit/receive duplexer, said first and second transmit/receive duplexer connecting to a two polarization antenna for transmitting and receiving signals;
said first and second transmit paths transmitting an in-phase and a quadrature phase output signals, respectively, said first and second receive paths receiving an in-phase and a quadrature phase input signals, respectively; and
a phase-tracked apparatus adjusting a respective phase and/or amplitude of said in-phase and quadrature phase output signals in said transmit chain for power combination of said in-phase and quadrature phase output signals at said two-polarization antenna, and a respective phase of said in-phase and quadrature phase input signals in said receive chain.
2. The system of claim 1 , wherein said phase-tracked apparatus includes, in each said first and second receive paths, a fixed phase adjuster connected between a quadrature hybrid coupler and a respective one of said first and second transmit/receive duplexers.
3. The system of claim 2 , wherein:
said transmit chain includes, in each said first and second transmit paths, a phase-tracked up-converter connecting to the OBP and connected to a phase-tracked high-power amplifier connected to a phase-tracked filter connecting to a respective said first and second transmit/receive duplexers, and said receive chain includes either a polarization selection switch connected to a common input filter connected to a common receiver connecting to the OBP or, for each said first and second receive paths, an input filter connected to a receiver connecting to the OBP;
and wherein said phase-tracked apparatus includes a frequency generation unit connecting to the OBP and providing a respective phase-tracked local oscillator signal to each said phase-tracked up-converters and either a local oscillator signal to said common receiver or a respective local oscillator signal to each said receiver, respectively.
4. The system of claim 2 , wherein:
in said transmit chain, said OBP connects to either, in each said first and second transmit paths, an up-converter connecting to, or a common up-converter connecting to a quadrature hybrid connecting to, in each said first and second transmit paths, a gain & phase adjuster connecting to a phase-tracked high-power amplifier connected to a phase-tracked filter connecting to a respective said first and second transmit/receive duplexers;
and wherein, in said receive chain, said quadrature hybrid coupler connects to either a polarization selection switch connected to a common input filter connected to a common receiver connecting to the OBP or, for each said first and second receive paths, an input filter connected to a receiver connecting to the OBP.
5. The system of claim 1 , wherein said OBP determines the polarization of at least one of said in-phase and a quadrature phase output signals of the first and second transmit paths and said in-phase and a quadrature phase input signals of the first and second receive paths.
6. The system of claim 1 , wherein at least one of the transmit and receive chains includes a polarization selection switch.
7. The system of claim 1 , wherein said OBP determines the polarization of one of said in-phase and a quadrature phase output signals of the first and second transmit paths and said in-phase and a quadrature phase input signals of the first and second receive paths, and the other one of the transmit and receive chains includes a polarization selection switch.
8. The system of claim 1 , further including a telecommand satellite link communicating with a ground station receiving said power combination of said in-phase and quadrature phase output signals, said ground station including:
a measurement unit receiving the power combination of said in-phase and quadrature phase output signals and measuring cross-polarization discrimination and/or axial ratio performance of the system;
a ground computing unit receiving and analyzing the measured system performance from the measurement unit by determining if the measured performance is either within a predetermined requirement range or performance optimization reachable to stop calibration, and, if not, generating a command signal with compensation adjustments of respective said phase and/or amplitude of said in-phase and quadrature phase output signals for up-link communication of said command signal via the telecommand satellite link.
9. The system of claim 8 , wherein said performance optimization being reachable is determined using a search method to iteratively optimizing the measured system performance.