Satellite up-link fade control
First Claim
1. A method of providing up-link fade control to a satellite not having AGC, said up-link having a modulator in a transmitting station, including the steps of:
- (a) determining plural characteristics for correcting channel non-linearity, each characteristic being determined for a different value of up-link fade, (b) determining a signal representative of up-link fade by beacon receiver means, (c) associating said signal with a correction characteristic for said up-link fade, (d) applying said correction characteristic associated with said sign to corrector means of said modulator, wherein said corrector means changes the modulator characteristics to modify constellation parameters at a satellite receiver.
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Accused Products
Abstract
A method up-link fade control for a satellite not having AGC, includes the steps of determining characteristics for correcting channel non-linearity, each characteristic being determined for a different value of up-link fade. A signal representative of up-link fade is determined by a beacon receiver and the signal is associated with a correction characteristic for the up-link fade. The correction characteristic associated with the signal is applied to a corrector of a modulator such that the corrector changes the modulator characteristics to modify constellation parameters at a satellite receiver.
54 Citations
62 Claims
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1. A method of providing up-link fade control to a satellite not having AGC, said up-link having a modulator in a transmitting station, including the steps of:
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(a) determining plural characteristics for correcting channel non-linearity, each characteristic being determined for a different value of up-link fade, (b) determining a signal representative of up-link fade by beacon receiver means, (c) associating said signal with a correction characteristic for said up-link fade, (d) applying said correction characteristic associated with said sign to corrector means of said modulator, wherein said corrector means changes the modulator characteristics to modify constellation parameters at a satellite receiver. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A method of providing up-link fade control to a satellite not having AGC, said up-link having a modulator in a transmitting station, including the steps of determining plural characteristics for correcting channel non-linearity, each characteristic being determined for a different value of up-link fade, determining a signal representative of up-link fade by beacon receiver means, associating said signal with a correction characteristic for said up-link fade, applying said correction characteristic associated with said signal to corrector means of said modulator, wherein said corrector means changes the modulator characteristics to modify constellation parameters at a satellite receiver, and said corrector means performs dynamic pre-correction by pre-distorting a signal which has been modulated to carry signals representative of digital data so as to reduce non-linear distortion in a signal channel containing root Nyquist bandpass filters in transmission and reception portions of said channel, there being provided a series connection of a static pre-distortion section configured to represent an inverse function of magnitude and phase distortion estimated to occur in said channel, and at least one dynamic pre-distortion section, the or each dynamic pre-distorting section including a forward model configured to represent magnitude and phase distortion in said channel, said signal being passed through cascaded sections whereby each successive dynamic pre-distorting section receives input from an output of a preceding dynamic pre-distorting section so that distortion in said channel is successively reduced to zero with each successive dynamic pre-distorting section.
- 16. A system for providing up-link fade control to a satellite not having AGC, said system including a modulator in a transmitting station of said up-link, means for determining plural characteristics for correcting channel non-linearity, each characteristic being determined for a different value of up-link fade, means for determining signal representative of up-link fade by beacon receiver means, means for associating said signal with a correction characteristic for said up-link fade, and means for applying said correction characteristic associated with said signal to corrector means of said modulator, wherein said corrector means changes the modulator characteristics to modify constellation parameters at a satellite receiver.
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30. A system for providing up-link fade control to a satellite not having AGC, said system including a modulator in a transmitting station of said up-link, means for determining plural characteristics for correcting channel non-linearity, each characteristic being determined for a different value of up-link fade, means for determining a signal representative of up-link fade by beacon receiver means, means for associating said signal with a correction characteristic for said up-link fade, means for applying said correction characteristic associated with said signal to corrector means of said modulator, wherein said corrector means changes the modulator characteristics to modify constellation parameters at a satellite receiver, and said corrector means performs dynamic pre-correction by pre-distorting a signal which has been modulated to carry signals representative of digital data so as to reduce non-linear distortion in a signal channel containing root Nyquist bandpass filters in transmission and reception portions of said channel, there being provided a series connection of static pre-distortion section configured to represent an inverse function of magnitude and phase distortion estimated to occur in said channel, and at least one dynamic pre-distortion section, the or each dynamic pre-distorting section including a forward model configured to represent magnitude and phase distortion in said channel, said signal being passed through cascaded sections whereby each successive dynamic pre-distorting section receives input from an output of a preceding dynamic pre-distorting section so that distortion in said channel is successively reduced to zero with each successive dynamic pre-distorting section.
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31. A method of providing up-link fade control to a satellite not having AGC, said up-link having a modulator in a transmitting station, including the steps of:
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(a) determining plural characteristics for correcting channel non-linearity, each characteristic being determined for a different value of up-link fade, (b) determining a signal representative of up-link fade by beacon receiver means, (c) associating said signal with a correction characteristic for said up-link fade, (d) applying said correction characteristic associated with said sign to corrector means of said modulator, wherein the beacon receiver means is polled such that, as the up-link fades, so a revised correction characteristic is used to modify the modulator so that the constellation parameters at a satellite receiver are maintained substantially undistorted.
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32. A system for providing up-link fade control to a satellite not having AGO, said system including a modulator in a transmitting station of said up-link, means for determining plural characteristics for correcting channel non-linearity, each characteristic being determined for a different value of up-link fade, means for determining a signal of up-link fade by beacon receiver means, means for association said signal with a correction characteristic for said up-link fade, and means for applying said correction characteristic associated with said signal to corrector means of said modulator, wherein the signal representative of up-link fade is determined by beacon receiver means which is polled such that, as the up-link fades, so a revised characteristic is used to modify the modulator so that the constellation parameters at the receiver are maintained substantially undistorted.
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33. A method of compensating up-link fade in a system having a modulator in a transmitting station, an up-link to a satellite having a transponder not having a AGC, and a down-link from a beacon of the satellite to a receiving station having a beacon receiver, the method including the steps of:
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determining a plurality of characteristics representative of up-link fade values indicated by a signal transmitted from the beacon transmitter of the satellite to the receiving station beacon receiver;
storing said plurality of characteristics to provide correction parameters for said modulator;
determining an up-link fade value by said beacon receiver and in dependence thereon selecting a stored characteristic, and applying the selected characteristic to a corrector means of said modulator, wherein the modulation of a transmitted signal from the transmitting station is pre-corrected such that the signal received by the receiving station has a constellation pattern that is substantially undistorted by channel non-linearities and up-link fading. - View Dependent Claims (34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47)
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48. A satellite communication system to compensate up-link fade, said system including:
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a modulator in a transmitting station, an up-link to a satellite having a transponder not having a AGC, a down-link from a beacon of the satellite to a receiving station having beacon receiver, determining means to provide a plurality of characteristics representative of up-link fade values indicated by a signal transmitted from the beacon transmitter of the satellite to the receiving station beacon receiver, storing means to store said plurality of characteristics to provide correction parameters for said modulator, wherein said beacon receiver determines an up-link fade value and in dependence thereon selects a stored characteristic, and applies the selected characteristic to a corrector means of said modulator, and the modulation of a transmitted signal from the transmitting station is pre-corrected such that the signal received by the receiving station has a constellation pattern that is substantially undistorted by channel non-linearities and up-link fading. - View Dependent Claims (49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62)
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Specification