Very small aperture terminal for satellite communication with direct conversion and electronic polarization orientation control

An outdoor unit (ODU) of a very small aperture terminal (VSAT) comprising:

• a modem configured to communicate with an indoor unit (IDU) to receive a baseband (BB) transmit signal;
• 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 satellite-RF transmit signal;
• and
• a transmit polarization amplifier coupled with the DUC to convert the satellite-RF transmit signal to the uplink signal by applying circular polarization;
• and
• an embedded computer, wherein the modem communicates with the IDU via the embedded computer.

A method of characterizing an outdoor unit (ODU) for a very small aperture terminal (VSAT), 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 satellite-RF transmit signal by direct up-conversion, to convert the satellite-RF transmit signal to an uplink signal by applying circular polarization, 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 subjecting 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.

A method of operating an outdoor (ODU) unit of a very small aperture terminal (VSAT), 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 satellite-RF transmit signal;
• amplifying the satellite-RF transmit signal through a transmit polarization amplifier 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;
• driving an antenna with the uplink signal for transmission of the uplink signal to the satellite;
• receiving a downlink signal from the satellite;
• converting the downlink signal to an 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.