Power control system for satellite communications
First Claim
1. In a satellite communication system of the type having a satellite transponder for receiving a plurality of uplink signals transmitted by a set of geographically distributed ground stations on earth and for retransmitting each uplink signal as a corresponding downlink signal, with the signal level of each downlink signal equal to the signal level of the corresponding received uplink signal multiplied by the gain of the satellite transponder, a system for compensating for a change in the received signal level of the satellite of a given local uplink signal comprising:
- a local ground station, being a first one of the ground stations in the set, for transmitting said given local uplink signal, which is retransmitted by the satellite as a local downlink signal, and for receiving the downlink signals retransmitted by the satellite;
a first beacon ground station, being a second one of the ground stations in the set located at a first geographical site having a low probability of an atmospheric attenuation event occurring, for transmitting a first beacon uplink signal which is retransmitted by the satellite as a first beacon downlink signal;
means for estimating the change of the signal level of said first beacon downlink signal received at said local ground station during the occurrence of a specific atmospheric attenuation event at said local ground station;
means for estimating the change of the signal level of the local downlink signal received at said local ground station during said given atmospheric attenuation event;
means for calculating the difference between said estimated signal changes of the local downlink signal and the first beacon signal; and
means for increasing the signal level of the local uplink signal by about the calculated difference to compensate for uplink attenuation due to the given atmospheric attenuation event at the local ground station.
2 Assignments
0 Petitions
Accused Products
Abstract
A system for compensating for varying attenuation of an uplink signal from a local node to a satellite. The system monitors two beacon signals and the local downlink signal to determine fade. An error signal, indicating the uplink fade, is generated and utilized to adjust the gain of the uplink transmitter to compensate for the fade.
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Citations
8 Claims
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1. In a satellite communication system of the type having a satellite transponder for receiving a plurality of uplink signals transmitted by a set of geographically distributed ground stations on earth and for retransmitting each uplink signal as a corresponding downlink signal, with the signal level of each downlink signal equal to the signal level of the corresponding received uplink signal multiplied by the gain of the satellite transponder, a system for compensating for a change in the received signal level of the satellite of a given local uplink signal comprising:
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a local ground station, being a first one of the ground stations in the set, for transmitting said given local uplink signal, which is retransmitted by the satellite as a local downlink signal, and for receiving the downlink signals retransmitted by the satellite; a first beacon ground station, being a second one of the ground stations in the set located at a first geographical site having a low probability of an atmospheric attenuation event occurring, for transmitting a first beacon uplink signal which is retransmitted by the satellite as a first beacon downlink signal; means for estimating the change of the signal level of said first beacon downlink signal received at said local ground station during the occurrence of a specific atmospheric attenuation event at said local ground station; means for estimating the change of the signal level of the local downlink signal received at said local ground station during said given atmospheric attenuation event; means for calculating the difference between said estimated signal changes of the local downlink signal and the first beacon signal; and means for increasing the signal level of the local uplink signal by about the calculated difference to compensate for uplink attenuation due to the given atmospheric attenuation event at the local ground station. - View Dependent Claims (2, 3)
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4. In a satellite communication system of the type having a satellite transponder for receiving a plurality of uplink signals transmitted by a set of geographically distributed ground stations on earth and for retransmitting each uplink signal as a corresponding downlink signal, with the signal level of each downlink signal equal to the signal level of the corresponding received uplink signal multiplied by the gain of the satellite transponder, a system for compensating for a change in the received signal level of the satellite of a given local uplink signal comprising:
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a local ground station, being a first one of the ground stations in the set, for transmitting said given local uplink signal, which is retransmitted by the satellite as a local downlink signal, and for receiving the downlink signals retransmitted by the satellite; a first beacon ground station, being a second one of the ground stations in the set located at a first geographical site having a low probability of an atmospheric attenuation event occurring, for transmitting a first beacon uplink signal which is retransmitted by the satellite as a first beacon downlink signal; means for estimating the change of the signal level of said first beacon downlink signal received at said local ground station during the occurrence of a specific atmospheric attenuation event at said local ground station; means for estimating the change of the signal level of the local downlink signal received at said local ground station during said given atmospheric attenuation event; and means for calculating the difference between said estimated signal changes of the local downlink signal and the first beacon signal.
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5. A method for allocating power in a satellite transmission system comprising the steps of:
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(a) providing a satellite transponder; (b) providing a set of geographically distributed ground stations; (c) designating one of said ground stations as a local node; (d) designating another one of said ground stations, located in a geographical region having a low probability of an atmospheric attenuation event occurring, as a beacon node; (e) transmitting a local uplink signal from said local node; (f) transmitting a beacon uplink signal from said beacon node; (g) receiving said local and beacon uplink signals at said satellite; (h) amplifying the received uplink signals by a fixed gain constant and retransmitting said amplified beacon uplink signal as a beacon downlink signal and said amplified local uplink signal as a local downlink signal; (i) receiving said beacon and local downlink signals at said local node; (j) estimating the non-attenuated average signal level of the received local and beacon downlink signals; (k) estimating the attenuated signal levels of the received local and beacon downlink signals during a given atmospheric attenuation event; and (l) utilizing the estimated non-attenuated and attenuated signal levels of the local and beacon downlink signals to estimate the attenuation of the local uplink signal during the given atmospheric attenuation event. - View Dependent Claims (6, 7)
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8. In a satellite communication system of the type having a satellite transponder for receiving a plurality of uplink signals transmitted by a set of geographically distributed ground stations on earth and for retransmitting each uplink signal as a corresponding downlink signal, with the signal level of each downlink signal equal to the signal level of the corresponding received uplink signal multiplied by the gain of the satellite transponder, where a first one of the ground stations in the set is a local ground station for transmitting a local uplink signal which is retransmitted by the satellite as a local downlink signal and for receiving the downlink signals retransmitted by the satellite, and where a second one of the ground stations in the set, located at a geographical site having a low probability of an atmospheric attenuation event occurring, is a beacon ground station for transmitting a first beacon uplink signal which is retransmitted by the satellite a first beacon downlink signal, a system for compensating for a change in the received signal level, at the satellite, of the local uplink signal comprising:
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means for estimating the change of the signal level of the local downlink signal received at said local ground station during said given atmospheric attenuation event; means for estimating the change of the signal level of first beacon downlink signal received at said local ground station during the occurrence of a specific atmospheric attenuation event at said local ground station; means for calculating the difference between said estimated signal changes of the local downlink signal and the first beacon signal; and means for increasing the signal level of the local uplink signal by about the calculated difference to compensate for uplink attenuation due to the given atmospheric attenuation event at the local ground station.
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Specification