Earth station transmission power control system

Claim 2

A transmission power control system for use in each earth station of at least a-part of a plurality of earth stations of a satellite communication network, said each earth station being responsive to a first signal for sending an up link signal to a satellite of said network, responsive to a beacon signal emitted by said satellite and reaching said each earth station with a beacon signal reception power for producing a second signal, and responsive to a return signal sent back by said satellite in response to said up link signal and reaching said each earth station with a return signal reception power for producing a third signal, said transmission power control system comprising controllable amplifying means for amplifying an information signal with a variable gain to produce said first signal and thereby to make said each earth station send said up link signal with a controllable transmission power dependent on said variable gain, beacon power signal producing means responsive to said second signal for producing a beacon power signal representative of said beacon signal reception power, return power signal producing means responsive to said third signal for producing a return power signal representative of said return signal reception power, and controlling means coupled to said amplifying means and responsive to said beacon and said return power signals for controlling said variable gain in consideration of a predetermined relationship between said beacon and said return signal reception powers.

Claim 3

A transmission power control system as claimed in Claim 1, wherein said controlling means controls said variable gain to substantially compensate for a reduction caused by an up link rain attenuation in said return signal reception power.

Claim 4

A transmission power control system as claimed in Claim)2, wherein said controlling means controls said variable gain in response to a ratio between said return signal reception power and said beacon signal reception power.

Claim 5

A transmission power control system as claimed in any of claims 1 to 3, wherein said beacon power signal producing means is responsive to said second signal for producing a first level signal as said beacon power signal, said first level signal being representative of a beacon reception level as said beacon signal reception power, said return power signal producing means being responsive to said third signal for producing a second level signal as said return power signal, said second level signal being representative of a return reception level as said return signal reception power, said controlling means comprising means responsive to a predetermined one of said first and said second level signals for producing a corrected signal representative of a corrected level in which a secondary level difference is compensated for, said secondary level difference being caused by rain between attenuations of said beacon and said return reception levels while said beacon and said return signals reach said each earth station from said satellite; means responsive to said corrected signal for producing a comparison signal representative of a comparison level which becomes equal to one of said beacon and said return reception levels in clear weather that the other of said first and said second level signals is representative of; means responsive to said comparison signal and said . other of the first and the second level signals for producing a difference signal representative of a primary level difference between said comparison level and said one of the beacon and the return reception levels, said primary level difference corresponding to said ratio; and means coupled to said amplifying means and responsive to said difference signal for controlling said variable gain to keep said primary level difference substantially equal to zero irrespective of weather.

Claim 6

A transmission power control system as claimed in in Claims wherein said controlling means controls said variable gain in response to a ratio between a return carrier-to-noise power ratio for said return signal reception power and a beacon carrier-to-noise power ratio for said beacon signal reception power.

Claim 7

A transmission power control system as claimed in Claim 5, wherein said beacon power signal producing means is responsive to said second signal for producing a first power ratio signal as said beacon power signal, said first power ratio signal being representative of said beacon carrier-to-noise power ratio, said return power signal producing means being responsive to said third signal for producing a second power ratio signal as said return power signal, said second power ratio signal being representative of said return carrier-to-noise power ratio, said controlling means comprising: means responsive to a predetermined one of said first and:said second power ratio signals for producing a corrected signal representative of a corrected power ratio in which a secondary power ratio difference is compensated for, said secondary power ratio difference being caused by rain between said beacon and said return carrier-to-noise power ratios while said beacon and said return signals reach said each earth station from said satellite; means responsive to said corrected signal for producing a comparison signal representative of a comparison power ratio which becomes equal to one of said beacon and said return carrier-to-noise power ratios in clear weather that the other of said first and said second power ratio signals is representative of; means responsive to said comparison signal and said other of the first and the second power ratio signals for producing a difference signal representative of a primary. power ratio difference between said comparison power ratio and said other of the beacon and the return carrier-to-noise power ratios, said primary power ratio difference corresponding to the ratio between said return and said beacon carrier-to-noise power ratios; and means coupled to said amplifying means and responsive to said difference signal for controlling said variable gain to keep said primary power ratio difference substantially equal to zero irrespective of weather.

Claim 8

A transmission power control system for use in each earth station of at least a part of specific stations among a plurality of earth stations of. a satellite communication network in which at least one particular station among said plurality of earth stations makes a satellite of said network radiate a radiation signal with an effective isotropically radiated power kept substantially constant irrespective of a rain loss to which an up link signal is subjected while being sent from said particular station to said satellite to be radiated as said radiation signal, said specific stations being those of said plurality of earth stations which are other than said at least one particular station, said each earth station being responsive to a first signal for sending a transmission signal to said satellite through an up link path, responsive to the radiation signal reaching said each earth station with a radiation signal reception power for producing a second signal, and responsive to a return signal sent back by said satellite in response to said transmission signal and reaching said each earth station with a return signal reception power for producing said a third signal,/ transmission power control system comprising controllable amplifying means for amplifying an information signal with a variable gain to produce said first signal and thereby to make said each earth station-send-said transmission signal with a controllable transmission power dependent on said variable gain, radiation power signal producing means responsive to said second signal for producing a radiation power signal representative of said radiation signal reception power, return power signal producing means responsive to said third signal for producing a return power signal representative of said return signal reception power, and controlling means coupled to said amplifying means and responsive to said radiation and said return power signals for controlling said variable gain in consideration of a predetermined relationship between said radiation and said return signal reception powers.

Claim 9

A transmission power control system for use in each earth station of at least a part of specific stations among a plurality of earth stations of. a satellite communication network in which at least one particular station among said plurality of earth stations makes a satellite of said network radiate a radiation signal with an effective isotropically radiated power kept substantially constant irrespective of a rain loss to which an up link signal is subjected while being sent from said particular station to said satellite to be radiated as said radiation signal, said specific stations being those of said plurality of earth stations which are other than said at least one particular station, said each earth station being responsive to a first signal for sending a transmission signal to said satellite through an up link path, responsive to the radiation signal reaching said each earth station with a radiation signal reception power for producing a second signal, and responsive to a return signal sent back by said satellite in response to said transmission signal and reaching said each earth station with a return signal reception power for producing said a third signal,/ transmission power control system comprising controllable amplifying means for amplifying an information signal with a variable gain to produce said first signal and thereby to make said each earth station-send-said transmission signal with a controllable transmission power dependent on said variable gain, radiation power signal producing means responsive to said second signal for producing a radiation power signal representative of said radiation signal reception power, return power signal producing means responsive to said third signal for producing a return power signal representative of said return signal reception power, and controlling means coupled to said amplifying means and responsive to said radiation and said return power signals for controlling said variable gain in consideration of a predetermined relationship between said radiation and said return signal reception powers.

Claim 10

A transmission power control system as claimed in Claim 7, wherein said controlling means controls said variable gain to substantially compensate for a reduction caused by an up link rain attenuation in said return signal reception power.

Claim 11

A transmission power control system as claimed 7 or in Claim/8, wherein said controlling means controls said variable gain in response to a ratio between said return signal reception power and said radiation signal reception power.

Claim 12

A transmission power control system as claimed in any of Claims 7 to 9, wherein said radiation power signal producing means is responsive to said second signal for producing a first level signal as said radiation power signal, said first level signal being representative of a first power level _ as said radiation signal reception power, said return power signal producing means being responsive to said third signal for producing a second level signal as said return power signal, said second level signal being representative of a second power level as said return signal reception level, said controlling means comprising: means responsive to a predetermined one of said first and said second level signals for producing a corrected signal representative of a corrected level in which a secondary level difference is compensated for, said secondary level difference being caused by rain between attenuations of said first and said second power levels while said radiation and said return signals reach said each earth station from said satellite; means responsive to said corrected signal for producing a comparison signal representative of a comparison level which becomes equal to one of said first and said second power levels in clear weather that the other of said first and said second level signal is representative of; means responsive to said comparison signal and said other of the first and the second level signals for producing a difference signal representative of a primary level difference between said comparison level and that one of said first and said second power levels which is represented by said other of the first and the second level signals, said primary level difference corresponding to said ratio; and means coupled to said amplifying means and responsive to said difference signal for controlling said variable gain to keep said primary level difference substantially equal to zero irrespective of weather.

Claim 13

A transmission power control system as claimed in any of Claims 7 to 10, wherein said radiation power signal producing means is responsive to said second signal for producing a first level signal as said radiation power signal, said first level signal being representative of a first power level as said radiation signal reception power, said return power signal producing means being responsive to said third signal for producing a second level signal as said return power signal, said second level signal being representative of a second power level as said return signal reception power, said controlling means comprising: memory means responsive to said first level signal for memorizing an initial level which said first level signal has in a predetermined initial state, said memory means producing an initial level signal representative of said initial level; means responsive to said first level signal and said initial level signal for producing a first difference signal representative of a first level difference between said first power level and said initial level; means responsive to said first difference signal for producing a corrected signal representative of a corrected level into which said first level difference is corrected in consideration of a celestial noise; means responsive to said corrected signal for producing an estimated signal representative of an estimated level difference which is estimated as said up link rain attenuation from a presumed correlationship between said corrected level and said up link rain attenuation; means responsive to said second level signal for producing a comparison signal representative of a comparison level which becomes equal to said first power level in said initial state; means responsive to said first level signal and said comparison signal for producing a second difference signal representative of a second level difference between said first power level and said comparison level; switch means selectively put in one of a first and a second state and responsive to said second difference signal for producing a compensation signal representative of a compensation level, said switch means rendering said compensation level equal to said second level difference when put in said first state, said switch means rendering, when put in said second state, said compensation level equal to the second level difference which said second difference signal represents in said initial state; and means coupled to said amplifying means and responsive to said estimated signal and said compensation signal for controlling said variable gain in relation to a sum of said estimated level difference and said compensation level so as to substantially compensate for said up link rain attenuation.

Claim 14

A transmission power control system as claimed any of) in any of Claims 7 to 11, wherein said controlling means controls said variable gain in response to a ratio between a return carrier-to-noise power ratio for said return signal reception power and a radiation carrier-to-noise power ratio for said radiation signal reception power.

Claim 15

A transmission power control system as claimed in Claim 12, wherein said radiation power signal producing means is responsive to said second signal for producing a first power ratio signal as said radiation power signal, said first power ratio signal being representative of a first power ratio as said radiation carrier-to-noise power ratio, said return signal producing means being responsive to said third signal for producing a second power ratio signal as said return power signal, said second power ratio signal being representative of a second power ratio as said return carrier-to-noise power ratio, said controlling means comprising: means responsive to a predetermined one of said first and said second power ratio signals for producing a corrected signal representative of a corrected power ratio in which a secondary power ratio difference is compensated for, said secondary power ratio difference being caused by rain between said first and said second power ratios while said radiation and said return signals reach said each earth station from said satellite; means responsive to said corrected signal for producing a comparison signal representative of a comparison power ratio which becomes equal to one of said first and said second power ratios in clear weather that the other of said first and said second power ratio signals is representative of; means responsive to said comparison signal and said other of the first and the second power ratio signals for producing a difference signal representative of a primary power ratio difference between said comparison power ratio and said other of the first and the second power ratios, said primary power ratio difference corresponding to the ratio between said return carrier-to-noise power ratio and said radiation carrier-to-noise power ratio; and means coupled to said amplifying means and responsive to said difference signal for controlling said variable gain to keep said primary power ratio difference substantially equal to zero irrespective of weather.

Claim 16

A transmission power control system as claimed in Claim 12, wherein said radiation power signal producing means is responsive to said second signal for producing a first power ratio signal as said radiation power signal, said first power ratio signal being representative of a first power ratio as said radiation carrier-to-noise power ratio, said return power signal producing means being responsive to said third signal for producing a second power ratio signal as said return power signal, said second power ratio signal being representative of a second power ratio as said return carrier-to-noise power ratio, said controlling means comprisingi memory means responsive to said first power ratio signal for memorizing an initial power ratio which said first power ratio signal has in a predetermined initial state, said memory means producing an initial power ratio signal representative of said initial power ratio; means responsive to said first power ratio signal and said initial power ratio signal for producing a first difference signal representative of a first power ratio difference between said first power ratio and said initial power ratio; means responsive to said first difference signal for producing a corrected signal representative of a corrected power ratio into which said first power ratio difference is corrected in consideration of a celestial noise; means responsive to said corrected signal for producing an estimated signal representative of an estimated power ratio difference which is estimated as said up link rain attenuation from a presumed correlationship between said corrected power ratio and said up link rain attenuation; means responsive to said second power ratio signal for producing a comparison signal representative of a comparison power ratio which becomes equal to said first power-ratio in said initial state; means responsive to said first power ratio signal and said comparison signal for producing a second difference signal representative of a second power ratio difference between said first power ratio and said comparison power ratio; switch means selectively put in one of a first and a second state and responsive to said second difference signal for producing a compensation signal representative of a compensation power ratio, said switch means rendering said compensation power ratio equal to said second power ratio difference when put in said first state, said switch means rendering, when put in said second state, said compensation power ratio equal to the second power ratio difference which said second difference signal represents in said initial state; and means coupled to said amplifying means and responsive to said estimated signal and said compensation signal for controlling said variable gain in relation to a sum of said estimated power ratio difference and said compensation power ratio so as to substantially compensate for said up link rain attenuation.

Claim 17

A transmission power control system for use in each earth station of at least a part of specific stations among a plurality of earth stations of a satellite communication network in which at least one particular station among said plurality of earth stations makes a satellite of said network radiate a radiation signal with an effective isotropically radiated power kept substantially constant irrespective of a rain loss to which an up link signal, is subjected while being sent from said particular station to said satellite to be radiated as said radiation signal, said specific stations being those of said plurality of earth stations which are other than said at least one particular station, said each earth station being responsive to a first signal for sending a transmission signal to said satellite through an up link path, responsive to the radiation signal reaching said each earth station with a radiation signal reception power for producing a second signal, and responsive to a return signal sent back by said satellite in response to said transmission signal and reaching said each earth station with a return signal reception power for producing said a third signal, / transmission power control system comprising controllable amplifying means for amplifying an information signal with a variable gain to produce said first signal and thereby to make said each earth station send said transmission signal with a controllable transmission power dependent on said variable gain, radiation power signal producing means responsive to said second signal for producing a radiation power signal representative of said radiation signal reception power, and return power signal producing means selectively put into and out of operation, said return power signal producing means, when put into operation, being responsive to said third signal for producing a return power signal representative of said return signal reception power, said transmission power control system further comprising controlling means coupled to said amplifying means and, when said return power signal producing means is put into operation, being responsive to said radiation and said return power signals for controlling said variable gain in consideration of a predetermined relationship between said radiation and said return signal reception powers, said controlling means, when said return power signal producing means is put out of operation, being responsive to only said radiation power signal for controlling said variable gain in consideration of said radiation signal reception power to substantially compensate for an up link rain attenuation.

Claim 18

A transmission power control system for use in each earth station of at least a part of specific stations among a plurality of earth stations of a satellite communication network in which at least one particular station among said plurality of earth stations makes a satellite of said network radiate a radiation signal with an effective isotropically radiated power kept substantially constant irrespective of a rain loss to which an up link signal, is subjected while being sent from said particular station to said satellite to be radiated as said radiation signal, said specific stations being those of said plurality of earth stations which are other than said at least one particular station, said each earth station being responsive to a first signal for sending a transmission signal to said satellite through an up link path, responsive to the radiation signal reaching said each earth station with a radiation signal reception power for producing a second signal, and responsive to a return signal sent back by said satellite in response to said transmission signal and reaching said each earth station with a return signal reception power for producing said a third signal, / transmission power control system comprising controllable amplifying means for amplifying an information signal with a variable gain to produce said first signal and thereby to make said each earth station send said transmission signal with a controllable transmission power dependent on said variable gain, radiation power signal producing means responsive to said second signal for producing a radiation power signal representative of said radiation signal reception power, and return power signal producing means selectively put into and out of operation, said return power signal producing means, when put into operation, being responsive to said third signal for producing a return power signal representative of said return signal reception power, said transmission power control system further comprising controlling means coupled to said amplifying means and, when said return power signal producing means is put into operation, being responsive to said radiation and said return power signals for controlling said variable gain in consideration of a predetermined relationship between said radiation and said return signal reception powers, said controlling means, when said return power signal producing means is put out of operation, being responsive to only said radiation power signal for controlling said variable gain in consideration of said radiation signal reception power to substantially compensate for an up link rain attenuation.

Claim 19

A transmission power control system for use in each earth station of at least a part of specific stations among a plurality of earth stations of a satellite communication network in which at least one particular station among said plurality of earth stations makes a satellite of said network radiate a radiation signal with an effective isotropically radiated power kept substantially constant irrespective of a rain loss to which an up link signal is subjected while being sent from said particular station to said satellite to be radiated as said radiation signal, said specific stations being those of said plurality of earth stations which are other than said at least one particular station, said each earth station being responsive to a first signal for sending a transmission signal to said satellite through an up link path and responsive to the radiation signal reaching said each earth station with a radiation signal reception power for producing a second signal,said transmission power control system comprising controllable amplifying means for amplifying an information signal with a variable gain to p roauce said first signal and thereby to make said each earth station send said transmission signal with a controllable transmission power dependent on said variable gain, radiation power signal producing means responsive to said second signal for producing a radiation power signal representative of said radiation signal reception power, and controlling means coupled to said amplifying means and responsive to said radiation power signal for controlling said variable gain in consideration of said radiation signal reception power.to substantially compensate for an up link rain attenuation to which said transmission signal is subjected when it rains at least at a part of said up link path.

Claim 20

A transmission power control system for use in each earth station of at least a part of specific stations among a plurality of earth stations of a satellite communication network in which at least one particular station among said plurality of earth stations makes a satellite of said network radiate a radiation signal with an effective isotropically radiated power kept substantially constant irrespective of a rain loss to which an up link signal is subjected while being sent from said particular station to said satellite to be radiated as said radiation signal, said specific stations being those of said plurality of earth stations which are other than said at least one particular station, said each earth station being responsive to a first signal for sending a transmission signal to said satellite through an up link path and responsive to the radiation signal reaching said each earth station with a radiation signal reception power for producing a second signal,said transmission power control system comprising controllable amplifying means for amplifying an information signal with a variable gain to p roauce said first signal and thereby to make said each earth station send said transmission signal with a controllable transmission power dependent on said variable gain, radiation power signal producing means responsive to said second signal for producing a radiation power signal representative of said radiation signal reception power, and controlling means coupled to said amplifying means and responsive to said radiation power signal for controlling said variable gain in consideration of said radiation signal reception power.to substantially compensate for an up link rain attenuation to which said transmission signal is subjected when it rains at least at a part of said up link path.

Claim 21

A transmission power control system as claimed in Claim l6, wherein said controlling means controls said variable gain in response to a reception power level of said radiation signal reception power.

Claim 22

A transmission power control system as claimed 16 or in Claim/17, wherein said radiation power signal producing means is responsive to said second signal for producing a power level signal as said radiation power signal, said power level signal being representative of said reception power level, said controlling means comprising: memory means responsive to said power level signal for memorizing an initial level which said power level signal has in a predetermined initial state, said memory means producing an initial level signal representative of said initial level; means responsive to said power level signal and said initial level signal for producing a difference signal representative of a level difference between said reception power level and said initial level; means responsive to said difference signal for producing a corrected signal representative of a corrected level into which said level difference is corrected in consideration of a celestial noise; means responsive to said corrected signal for producing an estimated signal representative of an estimated level difference which is estimated as said up link rain attenuation with reference to a presumed correlationship between said corrected level and said up link rain attenuation; and means coupled to said amplifying means and responsive to said estimated signal for controlling said variable gain in relation to said estimated level difference so as to substantially compensate for said up link rain attenuation.

Claim 23

A transmission power control system as claimed in Claim 16, wherein said controlling means controls said variable gain in response to a carrier-to-noise power ratio for said radiation signal reception power.

Claim 24

A transmission power control system as claimed in Claim 19, wherein said radiation power signal producing means is responsive to said second signal for producing a reception power ratio signal as said radiation power signal, said reception power ratio signal being representative of a reception power ratio as said carrier-to-noise power ratio, said controlling means comprising: memory means responsive to said reception power ratio signal for memorizing an initial power ratio which said reception power ratio signal has in a predetermined initial state,_said memory means producing an initial power ratio signal representative of said initial power ratio; means responsive to said reception power ratio signal and said initial power ratio signal for producing a difference signal representative of a difference power ratio between said reception power ratio and said initial power ratio; means responsive to said difference signal for producing a corrected signal representative of a corrected power ratio into which said power ratio difference is corrected in consideration of a celestial noise; means responsive to said corrected signal for producing an estimated signal representative of an estimated power ratio difference which is estimated as said up link rain attenuation with reference to a presumed correlationship between said corrected power ratio and said up link rain attenuation; and means coupled to said amplifying means and responsive to said estimated signal for controlling said variable gain in relation to said estimated power ratio difference so as to substantially compensate for said up link rain attenuation.

Claim 25

A transmission power control system as claimed in any one of Claims 1 through 6, wherein said information signal is a pilot information signal.

Claim 26

A transmission power control system as claimed in any one of Claims 1 through 20, wherein said information signal is a transmission information signal.

Claim 27

A transmission power control system as claimed in any one of Claims 1 through 20, wherein said information signal is a test information signal.

Claim 28

A transmission power control system as claimed in any one of Claims 1 through 20, wherein said information signal is a carrier.