Granted Patent B2

US 7,940,861 · App. 12/000,027 · Granted May 10, 2011

Abstract

Claims (37)

1. A method of reducing cycle slips in a carrier recovery loop for a phase detector, the method comprising:

receiving an input signal including a plurality of samples, each received sample having an in-phase (I) and quadrature-phase (Q) component;

providing the received input signal to a phase error estimator configured to determine a phase error estimate;

providing the determined phase error estimate to a loop filter, and

forming an output signal from the carrier recovery loop by subtracting an output of the loop filter from the received input signal, the method further including:

determining the phase error estimate based on a combination of an amplitude and a phase of the received samples and a probability measure for a specifically transmitted symbol, the phase error estimate improving phase tracking performance of the carrier recovery loop,

determining the phase error estimate based on a reliability of the sample, and

determining the phase error estimate (E ij 0 ) according to:

E ij 0 =( P ij •Φ ij )· A ij

wherein P ij represents the vector of probabilities of transmission of a specific sample in relation to each constellation point for the phase detector, Φ ij represents the vector of hard phase error estimates, and A ij represents the amplitude for the received sample.

2. The method according to claim 1 , wherein the phase detector is a QAM phase detector.

3. The method according to claim 1 , wherein the determination of the phase error estimate is optimized based on a desired signal-to-noise ratio for the input signal.

4. A phase detector, including a carrier recovery loop configured to reduce cycle slips, the phase detector comprising:

means for receiving an input signal including a plurality of samples, each received sample having an in-phase (I) and quadrature-phase (Q) component;

means for providing the received input signal to a phase error estimator;

means for determining a phase error estimate;

a loop filter;

means for providing the determined phase error estimate to the loop filter, and

means for forming an output signal from the carrier recovery loop by subtracting an output off the loop filter from the input signal, wherein

the phase error estimate is determined based on a combination of an amplitude and a phase of the received samples and a probability measure for a specifically transmitted symbol, the phase error estimate improving phase tracking performance of the carrier recovery loop,

the means for determining the phase error estimate is further configured to determine the phase error estimate based on a reliability of the sample, and

the means for determining the phase error estimate (E ij 0 ) is further configured to calculate the phase error estimate in accordance with:

E ij 0 =( P ij •Φ ij )· A ij

wherein P 1 represents the vector of probabilities of transmission of a specific sample in relation to each constellation point for the phase detector, Φ ij represents the vector of hard phase error estimates, and A ij represents the amplitude for the received sample.

5. The phase detector according to claim 4 , wherein the phase detector is a QAM phase detector.

6. The phase detector according to claim 4 , wherein the means for determining the phase error estimate is optimized based on a desired signal-to-noise ratio for the input signal.

7. The phase detector according to claim 4 , wherein the phase detector is used as a component in at least one of digital cable television system, cable modem application, a digital telecommunication system, a satellite television system and satellite communication system.

8. A computer program product comprising a non-transitory computer readable medium having stored thereon computer program means for causing a control unit to control phase detecting means for reducing cycle slips in a carrier recovery loop, wherein the computer program product comprises:

code for receiving an input signal including a plurality of samples, each received sample having an in-phase (I) and quadrature-phase (Q) component;

code for providing the received input signal to a phase error estimator configured to determine a phase error estimate;

code for providing the determined phase error estimate to a loop filter; and

code for forming an output signal from the carrier recovery loop by subtracting an output off the loop filter from the received input signal, wherein

the phase error estimate is determined based on a combination of an amplitude and a phase of the received samples and a probability measure for a specifically transmitted symbol,

the phase error estimate is further determined based on a reliability of the sample, and

the phase error estimate (E ij 0 ) is determined according to:

E ij 0 =( P ij •Φ ij )· A ij

wherein P ij represents the vector of probabilities of transmission of a specific sample in relation to each constellation point for the phase detector, Φ ij represents the vector of hard phase error estimates, and A ij represents the amplitude for the received sample.

Assignments (9)