Noise reduction system and method thereof
First Claim
1. A method for reducing echo noise in satellite communications in which a hub communicates with multiple remote stations via a satellite having a nonlinear satellite transponder, the method comprising the steps of:
- transmitting a transmit signal from the hub to the multiple remote stations, where the transmit signal contains at least one carrier;
providing, at the hub, a replica of the transmit signal to a buffer that provides an integer sample delay;
distorting, at the hub, the replica of the transmit signal according to nonlinearities of the satellite transponder to provide a distorted replica of the transmit signal;
determining, at the hub, a scaled, fractional-sample time-delayed, frequency-shifted, and attenuated version of the distorted replica of the transmit signal to provide a compensated distorted replica of the transmit signal; and
using, at the hub, the compensated distorted replica to represent the nonlinearities of the satellite transponder and reduce echo noise from a received aggregate signal received by the hub from the multiple remote stations via the satellite transponder;
wherein the distorting step further comprises applying a block conversion to the transmit signal to form the distorted replica occupying a predetermined frequency range and the determining step further comprises tracking the integer sample closest to a weight vector centroid of an adaptive filter to provide fractional-sample delay of the distorted replica.
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Accused Products
Abstract
The reduction of echo noise in satellite communications includes receiving an aggregate signal from multiple remote stations, where the aggregate signal includes a transmit signal, whose bandwidth is in the range of 0.1 MHz to 66 MHz, is previously sent from a hub to the multiple receiving stations, computing a scaled, delayed and distorted replica of the transmit signal and using the replica to compensate for satellite transponder nonlinearities and reduce echo noise interference from a received aggregate signal received by the hub from the multiple remote stations.
60 Citations
20 Claims
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1. A method for reducing echo noise in satellite communications in which a hub communicates with multiple remote stations via a satellite having a nonlinear satellite transponder, the method comprising the steps of:
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transmitting a transmit signal from the hub to the multiple remote stations, where the transmit signal contains at least one carrier; providing, at the hub, a replica of the transmit signal to a buffer that provides an integer sample delay; distorting, at the hub, the replica of the transmit signal according to nonlinearities of the satellite transponder to provide a distorted replica of the transmit signal; determining, at the hub, a scaled, fractional-sample time-delayed, frequency-shifted, and attenuated version of the distorted replica of the transmit signal to provide a compensated distorted replica of the transmit signal; and using, at the hub, the compensated distorted replica to represent the nonlinearities of the satellite transponder and reduce echo noise from a received aggregate signal received by the hub from the multiple remote stations via the satellite transponder; wherein the distorting step further comprises applying a block conversion to the transmit signal to form the distorted replica occupying a predetermined frequency range and the determining step further comprises tracking the integer sample closest to a weight vector centroid of an adaptive filter to provide fractional-sample delay of the distorted replica. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A system for reducing echo noise in satellite communications in which a hub communicates with multiple remote stations via a satellite having a nonlinear satellite transponder, the system comprising:
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transmitting a transmit signal from the hub to the multiple remote stations, where the transmit signal contains at least one carrier; a buffer at the hub for storing a replica of the transmit signal sent from the hub to the multiple receiving stations, the buffer having an integer sample delay; distorting means at the hub for distorting the replica of the transmit signal according to nonlinearities of the satellite transponder to provide a distorted replica of the transmit signal; receiving means for receiving an aggregate signal from the multiple remote stations, where the aggregate signal includes a distorted version of the transmit signal previously sent from the hub to the multiple receiving stations; determining means at the hub for determining a scaled, fractional-sample time-delayed, frequency-shifted, and attenuated version of the distorted replica of the transmit signal to provide a compensated distorted replica of the transmit signal; and echo noise reduction means for using the compensated distorted replica to represent the nonlinearities of the satellite transponder and reduce echo noise from a received aggregate signal received by the hub from the multiple remote stations via the satellite transponder; wherein the distorting means further comprises means for applying a block conversion to the transmit signal to form the distorted replica occupying a predetermined frequency range and the determining means further tracks the integer sample closest to a weight vector centroid of an adaptive filter to provide factional-sample delay of the distorted replica. - View Dependent Claims (10, 11, 12, 13, 14)
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15. An article of manufacture, comprising a computer-readable medium having stored thereon instructions for echo noise in satellite communications in which a hub communicates with multiple remote stations via a satellite having a nonlinear satellite transponder, said instructions which, when performed by a processor, cause the processor to execute the steps comprising the steps of:
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transmitting a transmit signal from the hub to the multiple remote stations, where the transmit signal contains at least one carrier; storing in a buffer at the hub, a replica of the transmit signal sent from the hub to the multiple receiving stations, the buffer having an integer sample delay; distorting, at the hub, the replica of the transmit signal according to nonlinearities of the satellite transponder to provide a distorted replica of the transmit signal; receiving an aggregate signal from multiple remote stations, where the aggregate signal includes a distorted version of the transmit signal previously sent from the hub to the multiple receiving stations; determining, at the hub, a scaled, fractional-sample time-delayed, frequency-shifted, and attenuated version of the distorted replica of the transmit signal to provide a compensated distorted replica of the transmit signal; and using, at the hub, the compensated distorted replica to represent the nonlinearities of the satellite transponder and reduce echo noise from a received aggregate signal received by the hub from the multiple remote stations via the satellite transponder; wherein the distorting step further comprises applying a block conversion to the transmit signal to form the distorted replica occupying a predetermined frequency range and the determining step further comprises tracking the integer sample closest to a weight vector centroid of an adaptive filter to provide a fractional-sample delay of the distorted replica. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification