Multi-carrier transmission systems
First Claim
1. A receiver, for use with a multi-carrier transmission system using orthogonal carriers, in which a receiver sampling clock is synchronized with a transmitter sampling clock by phase locking said receiver sampling clock to a pilot carrier, said receiver comprising:
- a feedback loop configured to control an oscillator means, said feedback loop using a feedback signal representative of an argument estimate of said pilot carrier, wherein said feedback signal is derived from an approximation of an argument of a complex number representative of said pilot carrier, said approximation retaining a full resolution of said complex number, and wherein said feedback loop controls said oscillator means so that said pilot argument tends to zero.
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Accused Products
Abstract
A multi-carrier transmission system using DMT. It is known to recover a receiver sample and clock from a reserved carrier, a pilot carrier having a fixed phase. A sampling clock oscillator in a receiver is then phase locked to the pilot carrier. Multi-carrier receivers, such as DMT receivers, are normally equipped with an FFT processor. A complex number representing the pilot carrier is then available from the FFT processor output. If an FFT processor is not available, a one frequency DFT processor can be provided to produce a complex estimate of the pilot carrier. In a DMT system, frame synchronization is handled separately from sampling clock synchronization, although the two processes are intimately related and frame synchronization must be acquired before sampling clock synchronization.
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Citations
30 Claims
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1. A receiver, for use with a multi-carrier transmission system using orthogonal carriers, in which a receiver sampling clock is synchronized with a transmitter sampling clock by phase locking said receiver sampling clock to a pilot carrier, said receiver comprising:
a feedback loop configured to control an oscillator means, said feedback loop using a feedback signal representative of an argument estimate of said pilot carrier, wherein said feedback signal is derived from an approximation of an argument of a complex number representative of said pilot carrier, said approximation retaining a full resolution of said complex number, and wherein said feedback loop controls said oscillator means so that said pilot argument tends to zero. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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14. A receiver as claimed in claim 13, wherein K=2.
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15. A transceiver comprising:
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a transmitter; and
a receiver, for use with a multi-carrier transmission system using orthogonal carriers, in which a receiver sampling clock is synchronized with a transmitter sampling clock by phase locking said receiver sampling clock to a pilot carrier, said receiver including a feedback loop configured to control an oscillator means, said feedback loop using a feedback signal representative of an argument estimate of said pilot carrier, wherein said feedback signal is derived from an approximation of an argument of a complex number representative of said pilot carrier, said approximation retaining a full resolution of said complex number, and wherein said feedback loop controls said oscillator means so that said pilot argument tends to zero. - View Dependent Claims (18, 19)
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16. A multi-carrier transmission system using orthogonal carriers, in which a receiver sampling clock is phase locked to a pilot carrier, wherein said multi-carrier transmission system comprises:
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two transceivers, wherein each one of said two transceivers includes a transmitter, and a receiver, including a feedback loop configured to control an oscillator means, said feedback loop using a feedback signal representative of an argument estimate of said pilot carrier, wherein said feedback signal is derived from an approximation of an argument of a complex number representative of said pilot carrier, said approximation retaining a full resolution of said complex number, and wherein said feedback loop controls said oscillator means so that said pilot argument tends to zero.
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17. A method for synchronizing a receiver clock with a transmitter clock, in which the transmitter transmits a pilot signal in a multi-carrier transmission system, said method comprising the steps of;
controlling a sampling clock in said receiver so that an argument of said pilot carrier converges to zero, and said pilot carrier argument is approximated by arithmetic operation on a complex number representative of said pilot signal.
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20. A method for synchronizing a receiver sampling clock to a transmitter sampling clock in a multi-carrier transmission system using orthogonal carriers, in which said receiver sampling clock is synchronized with said transmitter sampling clock by phase locking said receiver sampling clock to a pilot carrier transmitted by said transmitter, said method comprising the steps of:
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deriving a complex number representative of said pilot carrier;
deriving from said complex number an approximation of an argument of said pilot carrier;
using said approximation of said argument as a feedback signal to control said receiver sampling clock, so that said feedback signal tends to zero. - View Dependent Claims (21, 23, 24, 25, 26, 27, 28, 29, 30)
using an approximation, A, to said pilot carrier estimation, wherein;
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30. A method as claimed in claim 29, wherein K=2.
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22. A method as claimed in 20, wherein said multi-carrier transmission system comprises a DMT based VDSL system.
Specification