System and method for communicating via a satellite in an inclined geosynchronous orbit
First Claim
1. A method of communicating via a satellite, the method comprising:
- locating a target satellite in an inclined geosynchronous orbit;
pointing an antenna at an aiming point offset from a geostationary arc, the antenna having a radiation pattern;
estimating a maximum boresite Equivalent Isotropic Radiated Power (EIRP) Spectral Density (SD) that complies with a predetermined maximum off-axis EIRP SD mask along the geostationary arc based on the antenna radiation pattern and the aiming point;
encoding information into a radio frequency signal based on an information rate, coding parameters, and modulation parameters; and
transmitting the radio frequency signal to the target satellite at a transmitted boresite EIRP SD based on the maximum boresite EIRP SD.
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Abstract
A hub terminal and remote client communicate via a target satellite in an inclined geosynchronous orbit. As the target satellite ascends or descends away from the geostationary arc, the signal strength of the uplink channel is increased without increasing the level of interference with adjacent geostationary satellites. The increased angular separation from adjacent satellites also decreases downlink interference. The resulting increase in signal to interference ratio permits adjustment of the modulation and coding parameters to increase spectral efficiency. The antenna gain pattern is modeled based on antenna characteristics and the model may be supplemented with measurements of a signal relayed by adjacent satellites. The method permits intermittent communication from locations where the geostationary arc is blocked or using disadvantaged antennas that would be impractical for use with geostationary satellites. In some circumstances, it is desirable to deliberately mis-steer the antenna slightly away from the target satellite.
28 Citations
20 Claims
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1. A method of communicating via a satellite, the method comprising:
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locating a target satellite in an inclined geosynchronous orbit; pointing an antenna at an aiming point offset from a geostationary arc, the antenna having a radiation pattern; estimating a maximum boresite Equivalent Isotropic Radiated Power (EIRP) Spectral Density (SD) that complies with a predetermined maximum off-axis EIRP SD mask along the geostationary arc based on the antenna radiation pattern and the aiming point; encoding information into a radio frequency signal based on an information rate, coding parameters, and modulation parameters; and transmitting the radio frequency signal to the target satellite at a transmitted boresite EIRP SD based on the maximum boresite EIRP SD. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A communications transmitter comprising:
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a directional antenna having a radiation pattern; an antenna pointing control configured to point the antenna at an aiming point offset from a geostationary arc; and a modulator configured to convert information into a radio frequency signal at an information rate using encoding parameters; an amplifier configured to amplify the radio frequency signal such that the signal is transmitted from the antenna with a transmitted boresite EIRP SD; and a processor programmed to determine a maximum boresite EIRP SD that complies with a predetermined maximum off-axis EIRP SD mask along the geostationary arc based on the antenna radiation pattern and the aiming point and to control the amplifier based on the maximum boresite EIRP SD. - View Dependent Claims (11, 12, 13, 14, 15)
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16. A communications receiver comprising:
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a directional antenna configured to receive a radio frequency signal from a target satellite in an inclined geosynchronous orbit; a demodulator configured to convert the radio frequency signal into information at a spectral efficiency; and a processor programmed to vary demodulator settings to increase the spectral efficiency as a declination of the target satellite increases. - View Dependent Claims (17, 18, 19, 20)
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Specification