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EP-4736347-A1 - VERY SMALL APERTURE TERMINAL FOR SATELLITE COMMUNICATION WITH DIRECT CONVERSION AND ELECTRONIC POLARIZATION ORIENTATION CONTROL

EP4736347A1EP 4736347 A1EP4736347 A1EP 4736347A1EP-4736347-A1

Abstract

Techniques are described for direct conversion and dynamic polarization control in a very small aperture terminal (VSAT) outdoor unit (ODU). The ODU includes a direct up-converter and/or a direct down-converter for converting in a single stage between a baseband frequency and a satellite radiofrequency band (e.g., Ka band). The ODU also includes a polarization amplifier that integrates high-power amplification with circular polarization orientation control. For example, the direct up-converter directly converts a baseband signal to a low-power satellite-RF transmit signal, and the polarization amplifier converts the low-power satellite-RF transmit signal to an uplink signal having high gain and selected circular polarization. The ODU can further include an integrated embedded computer and modem.

Inventors

  • CHONG, JOSEPH
  • EAPEN, GEORGE
  • JOSHI, RAJESH

Assignees

  • Hughes Network Systems, LLC

Dates

Publication Date
20260506
Application Date
20240611

Claims (20)

  1. 1. An outdoor unit (ODU) of a very small aperture terminal (VS AT) comprising: a modem configured to communicate with an indoor unit (IDU) to receive a baseband (BB) transmit signal; and a transmit path to output an uplink signal to a satellite, the transmit path comprising: a direct up-converter (DUC) coupled with the modem to convert the BB transmit signal to a low-power satellite-RF transmit signal; and a transmit polarization amplifier coupled with the DUC to convert the low-power satellite-RF transmit signal to the uplink signal by applying circular polarization and high gain.
  2. 2. The outdoor unit of claim 1 wherein the transmit polarization amplifier applies a high gain of at least 29 dB.
  3. 3. The outdoor unit of claim 1 wherein the DUC is implemented on a first monolithic IC and the transmit polarization amplifier is implemented on a second monolithic IC separate from the first monolithic IC.
  4. 4. The outdoor unit of claim 1 further comprising: a receive path to receive a downlink signal from the satellite, the receive path comprising: an receive polarization amplifier to convert the downlink signal to a amplified satellite-RF receive signal; and a direct down-converter (DDC) coupled with receive polarization amplifier to convert the amplified satelhte-RF receive signal to a BB receive signal and to output the BB receive signal to the modem.
  5. 5. The outdoor unit of claim 4 further comprising: an orthomode transducer (OMT) to integrate the transmit polarization amplifier and the receive polarization amplifier.
  6. 6. The outdoor unit of claim 4 wherein the DUC and DDC are implemented on a same monolithic IC.
  7. 7. The outdoor unit of claim 1 wherein the DUC converts based on calibration information previously generated by a characterization process and stored at the modem.
  8. 8. The outdoor unit of claim 1 further comprising: an embedded computer, wherein the modem communicates with the IDU via the embedded computer.
  9. 9. The outdoor unit of claim 8 wherein: the modem provides the BB transmit signal to the DUC; and the embedded computer provides transmit control signals to the DUC.
  10. 10. The outdoor unit of claim 1 wherein the transmit polarization amplifier is to apply the circular polarization by selecting a circular polarization orientation based on transmit control signals.
  11. 11. The outdoor unit of claim 1 wherein the transmit polarization amplifier compnses: a first Lange coupler that steers a signal through one of two series of gain stages; and a second Lange coupler to steer the output of the one of two series of gain stages to one of two polarization outputs.
  12. 12. The outdoor unit of claim 1 wherein the uplink signal is at Ka band signal.
  13. 13. A method of characterizing an outdoor unit (ODU) for a very small aperture terminal (V SAT), the ODU configured to operate in a calibration mode or in an operational mode, to convert a baseband transmit signal received via a transmit input of the ODU into a low-power satellite-RF transmit signal by direct up-conversion, to convert the low-power satellite-RF transmit signal to an uplink signal by applying circular polarization and high gain, and to output the uplink signal via a transmit output, the method comprising: connecting the ODU to a test fixture by coupling a controller of the test fixture to the transmit input of the ODU and coupling a dummy load of the test fixture to the transmit output of the ODU; and iteratively, for each of a sequence of P * Q test conditions, each iteration test condition corresponding to a unique combination of an iteration frequency selected by the controller from a range of P frequencies and an iteration temperature selected by the controller from a range of Q temperatures: commanding the ODU, by the controller, to output an iteration power output responsive to subjecting the ODU, by the test fixture, to the iteration frequency and the iteration temperature: commanding the ODU, by the controller, to output an iteration amplitude responsive to subj ecting the ODU, by the test fixture, to the iteration frequency and the iteration temperature; and storing the iteration power output and the iteration amplitude in a database in association with the iteration frequency and the iteration temperature.
  14. 14. The method of claim 13 wherein: the storing comprises loading the database in a modem of the ODU; and the modem is configured, during operation of the ODU in the operational mode, to dynamically derive an optimal power setting based on the database and responsive to detecting an operating frequency and operating temperature.
  15. 15. The method of claim 13 wherein: the storing comprises loading the database in a modem of the ODU; and the modem is configured, during operation of the ODU in the operational mode, to dynamically derive an optimal predistortion setting based on the database and responsive to detecting an operating frequency and operating temperature.
  16. 16. A method of operating an outdoor (ODU) unit of a very 7 small aperture terminal (VS AT), the method comprising: receiving, from an indoor unit (IDU). a digital information signal to be transmitted by the ODU to a satellite; separating the digital information signal into control data and a baseband (BB) signal; up-converting the BB signal with a single-stage up-converter operating at a low power level to produce a low-power satellite-RF transmit signal; amplifying the low-power satellite-RF transmit signal through a transmit polarization amplifier with a high gain to generate an uplink signal, the uplink signal having a circular polarization selected based on applying a control signal to the transmit polarization amplifier to select one of two outputs of the transmit polarization amplifier wherein each output of the transmit polarization amplifier corresponds to a respective complementary polarization orientation; and driving an antenna with the uplink signal for transmission of the uplink signal to a satellite.
  17. 17. The method of claim 16 wherein the high gain of the transmit polarization amplifier is greater than 29 dB.
  18. 18. The method of claim 16 wherein: the selecting the one of two outputs of the transmit polarization amplifier drives a respective one of two inputs of a polarizing orthomode transducer (OMT); and the driving the antenna comprises driving the antenna with an output of the polarizing OMT.
  19. 19. The method of claim 18 wherein: driving a first of the two inputs of the polarizing OMT causes the circular polarization orientation to be left hand circular polarization (LHCP); and driving a second of the two inputs of the polarizing OMT causes the circular polarization orientation to be right hand circular polarization (RHCP).
  20. 20. The method of claim 16 further comprising: receiving a downlink signal from the satellite; converting the downlink signal to a amplified satellite-RF receive signal by a receive polarization amplifier; down-converting the amplified satellite-RF receive signal directly to a BB receive signal; and outputting the BB receive signal to the IDU.

Description

VERY SMALL APERTURE TERMINAL FOR SATELLITE COMMUNICATION WITH DIRECT CONVERSION AND ELECTRONIC POLARIZATION ORIENTATION CONTROL CROSS REFERENCE TO RELATED APPLICATION [0001] This application claims priority to U.S. Patent Application No. 18/345,434, filed June 30, 2023, entitled “VERY SMALL APERTURE TERMINAL FOR SATELLITE COMMUNICATION WITH DIRECT CONVERSION AND ELECTRONIC POLARIZATION ORIENTATION CONTROL,” which is hereby incorporated by reference in its entirety. BACKGROUND [0002] Satellite communication services are typically delivered to a customer premises via a very small aperture terminal (VSAT) installed at the premises. Conventionally, the VSAT has transmit path and receive path electronics that are separated between an indoor unit (IDU) and an outdoor unit (ODU). For example, an embedded computer and modem tend to be implemented in the IDU, while radio functions (e.g., components for modulation, conversion, filtering, amplification, polarization, etc.) tend to be implemented in the ODU. Because of this separation, control signals typically need to travel through an interconnect cable, which can involve modulating and multiplexing the control signals, thereby limiting control capabilities and increasing response time. [0003] Further, this conventional separation and/or other conventional constraints have tended to drive certain ODU radio function designs. As one example, conventional ODUs tend to have a radio function that relies on multiple conversion stages, including conversion through an intermediate frequency between baseband and satellite band. For example, ODUs tend to be designed for superheterodyne conversion. As another example, conventional ODUs tend to have a hard-wired polarization orientation. For example, changing polarization orientation of the transmit and/or receive path typically requires an installer to physically change the orientation of components, or otherwise manually reconfigure the ODU. SUMMARY [0004] Systems and methods are described for direct conversion and dynamic polarization control in a very small aperture terminal (VS AT) outdoor unit (ODU). The VS AT can include an embedded computer and an integrated modem. The ODU includes a direct up- converter and/or a direct down-converter for converting in a single stage between a baseband frequency and a satellite radiofrequency band (e.g., Ka band). The ODU also includes a polarization amplifier that integrates high-power amplification with circular polarization orientation control. For example, the direct up-converter directly converts a baseband signal to a low -power satellite-RF transmit signal, and the polarization amplifier converts the low - pow er satellite-RF transmit signal to an uplink signal having high gain and selected circular polarization. The ODU can further include an integrated embedded computer and modem. BRIEF DESCRIPTION OF THE DRAWINGS [0005] A further understanding of the nature and advantages of various embodiments may be realized by reference to the following figures. In the appended figures, similar components or features may have the same reference label. Further, various components of the same type may be distinguished by following the reference label by a dash and a second label that distinguishes among the similar components. If only the first reference label is used in the specification, the description is applicable to any one of the similar components having the same first reference label irrespective of the second reference label. [0006] FIG. 1 is a block diagram of a very' small aperture terminal (VS AT); [0007] FIG. 2 Is a block diagram of a polarization control unit; [0008] FIG. 3 is a schematic of a transmit polarization amplifier; [0009] FIG. 4 illustrates the power flow that drives the right-hand circular polarization (RHCP) output to the orthomode transducer (OMT) left-hand circular polarization (LHCP) input; [0010] FIG. 5 illustrates the power flow that drives the LHCP output to the OMT RHCP input; [0011] FIG. 6 is a block diagram of a conventional two stage up-converter also known as a superheterodyne transmitter; [0012] FIG. 7 is a conventional block diagram of a superheterodyne receiver; [0013] FIG. 8 shows a block diagram of a direct up-converter; [0014] FIG. 9 is a block diagram of a direct down-converter; [0015] FIG. 10 is a conventional spectral graph of multiple frequency transition stages relied on by a superheterodyne transmitter; [0016] FIG. 11 is a graph of direct baseband-to-radiofrequency transition in a direct up- converter; [0017] FIG. 12 is a flow diagram of an illustrative method for characterizing an outdoor unit (ODU) for a VS AT; and [0018] FIG. 13 is a flow diagram of an illustrative method for operating an ODU of a VSAT. DETAILED DESCRIPTION [0019] Disclosed embodiments relate to a very small aperture terminal (VSAT), a smallsized earth station used in the transmission and reception of data, voice, and video signals over a satellite communication networ