Fast resynchronization system for high-speed data transmission
First Claim
1. A system for estimating a timing phase and a carrier phase offset of a received signal corresponding to a known transmitted signal for resuming high-speed data reception of transmitted data signals that were previously interrupted, the system comprising:
- means for modifying the received signal to produce a modified signal;
means for determining a discrete Fourier transform (DTF) of the modified signal;
means for determining a DFT of the known transmitted signal;
means for determining a complex conjugate of the DFT of the known transmitted signal;
a multiplier for calculating a product of the DFT of the modified signal and the complex conjugate of the DFT of the known transmitted signal;
a phase estimator for obtaining a phase function based upon the product of the multiplier, the phase function being a linear function of the carrier phase offset and timing phase offset; and
means for estimating the timing phase offset and carrier phase offset according to the phase function.
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Accused Products
Abstract
A system for resynchronizing the timing and carrier phases of a modem receiver signal to enable the receiver to quickly reacquire the timing phase and the carrier phase, and thereby restart the demodulation process. The system provides accurate estimates of the timing and carrier phases, as well as a gain correction factor to provide for proper alignment for decoding. The discrete Fourier transform of the received signal is multiplied by the complex conjugate of the discrete Fourier transform of the transmitted signal to produce estimates of the desired phases. Gain control and carrier phase control are performed to determine corresponding error signals to adapt the resultant estimated timing and carrier phases, and gain correction.
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Citations
28 Claims
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1. A system for estimating a timing phase and a carrier phase offset of a received signal corresponding to a known transmitted signal for resuming high-speed data reception of transmitted data signals that were previously interrupted, the system comprising:
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means for modifying the received signal to produce a modified signal; means for determining a discrete Fourier transform (DTF) of the modified signal; means for determining a DFT of the known transmitted signal; means for determining a complex conjugate of the DFT of the known transmitted signal; a multiplier for calculating a product of the DFT of the modified signal and the complex conjugate of the DFT of the known transmitted signal; a phase estimator for obtaining a phase function based upon the product of the multiplier, the phase function being a linear function of the carrier phase offset and timing phase offset; and means for estimating the timing phase offset and carrier phase offset according to the phase function. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A system for resynchronizing timing and carrier phase by estimating a timing phase offset and a carrier phase offset of a received signal y(n) corresponding to a known transmitted signal x(n) for resuming high-speed data reception of transmitted signals that were previously interrupted, the system comprising:
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means for modifying the received signal y(n) to produce a modified signal x"'"'"'(n); means for determining a discrete Fourier transform (DFT) X"'"'"'(k) of the modified signal x"'"'"'(n) at more than one value of k, the DFT having plural input samples; means for determining a DFT X(k) of the known transmitted signal at more than one value of k; means for determining a complex conjugate X*(K) of the DFT of the known transmitted signal; a multiplier for multiplying X"'"'"'(k) by X*(k); a phase estimator for obtaining an estimate of a phase function;
space="preserve" listing-type="equation">ψ
(k)=φ
-2π
τ
K/Nthe phase function being a linear function of k with a value φ
at k=0 representing carrier phase offset and a slope 2π
τ
/N representing timing phase offset; andmeans for estimating the timing phase offset τ and
carrier phase offset φ
according to the phase function. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. A method for resynchronizing timing and carrier phases by estimating a timing phase offset and a carrier phase offset of a received signal y(n) corresponding to a known transmitted signal x(n) for resuming high-speed data reception of transmitted signals that were previously interrupted, the method comprising the steps of:
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modifying the received signal y(n) to produce a modified signal x"'"'"'(n); determining a discrete Fourier transform (DFT) X"'"'"'(k) of the modified signal x"'"'"'(n) at more than one value of k; determining a DFT X(k) of the known transmitted signal; calculating a complex conjugate X*(k) of the DFT of the known transmitted signal; multiplying X"'"'"'(k) by X*(k); obtaining an estimate of the phase function;
space="preserve" listing-type="equation">ψ
(k)=φ
-2π
τ
k/Nthe phase function being a linear function of k with a value φ
at k=0 representing carrier phase offset and a slope 2π
τ
/N representing timing phase offset; andestimating the timing phase offset τ and
carrier phase offset φ
according to the phase function. - View Dependent Claims (25, 26, 27, 28)
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Specification