Method and apparatus for correcting symbol timing

1. A method for correcting a symbol timing of a receiver, the receiver receiving a signal transmitted from a transmitter according to a symbol period, the method comprising:

sampling the signal according to a sampling period to generate N sampled data, wherein the sampling period is half the symbol period, wherein N is a positive integer;

selecting M data from the N sampled data to be a first data set according to a timing recovery algorithm (TR algorithm);

calculating the first data set to generate a first timing metric according to the TR algorithm;

selecting M data from the N sampled data to be a second data set according to the TR algorithm;

calculating the second data set to generate a second timing metric according to the TR algorithm;

changing the sign of the first timing metric; and

correcting the symbol timing according to the sign changed first timing metric and the second timing metric;

wherein the first data set comprises a K th data and a K th +2) data, the second data set comprising a (K th +1) data and a K th +3) data; K and M are positive integers; and M is equal to or greater than 2.

2. The method of claim 1 , further comprising:

performing an operation on the sign changed first timing metric and the second timing metric to generating an operating result, and

correcting the symbol timing according to the operating result.

3. The method of claim 1 , further comprising:

adding the sign changed first timing metric from the second timing metric to generate a third timing metric;

wherein the step of correcting the symbol timing utilizes the third timing metric.

4. The method of claim 1 , further comprising:

adding the second timing metric from the sign changed first timing metric to generate a third timing metric;

wherein the step of correcting the symbol timing utilizes the third timing metric.

5. The method of claim 1 , wherein the TR algorithm is a Mueller and Muller method.

6. An apparatus for correcting a symbol timing of a receiver, the receiver receiving a signal transmitted from a transmitter based on a symbol period, the apparatus comprising:

a sampling circuit for sampling the signal based on a sampling period to generate N sampled data, wherein the sampling period is half the symbol period, wherein N is a positive integer;

a timing error detector, coupled to the sampling circuit, for

selecting M data from the N sampled data to be a first data set according to a timing recovery algorithm (TR algorithm);

calculating the first data set to generate a first timing metric according to the TR algorithm;

selecting M data from the N sampled data to be a second data set according to the TR algorithm; and

calculating the second data set to generate a second timing metric according to the TR algorithm;

a timing metric processing circuit, coupled to the timing error detector and the symbol timing correction circuit, for changing the sign of the first timing metric; and

a symbol timing correction circuit, coupled to the timing error detector, for correcting the symbol timing according to the sign changed first timing metric and the second timing metric;

wherein the first data set comprises a K th data and a K th +2) data, the second data set comprising a (K th +1) data and a K th +3) data; K and M are positive integers; and M is equal to or greater than 2.

7. The apparatus of claim 6 ,

wherein the timing metric processing circuit performs an operation on the sign changed first timing metric and the second timing metric to generating an operating result and the symbol timing correction circuit corrects the symbol timing according to the operating result.

8. The apparatus of claim 6 , wherein the timing metric processing circuit adds the sign changed first timing metric from the second timing metric to generate a third timing metric; and the symbol timing correction circuit corrects the symbol timing according to the third timing metric.

9. The apparatus of claim 6 , wherein the timing metric processing circuit adds the second timing metric from the sign changed first timing metric to generate a third timing metric; and the symbol timing correction circuit corrects the symbol timing according to the third timing metric.

10. The apparatus of claim 6 wherein the TR algorithm is a Mueller and Muller method.

11. A method for correcting a symbol timing, the method being utilized to make a receiver receive a signal transmitted from a transmitter according to a symbol timing, and the signal corresponding to a symbol period, the method comprising:

sampling the signal based on a sampling period to generate N sampled data in sequence, wherein the sampling period is less than the symbol period and N is a positive integer;

selecting M data out of the N sampled data and generating a plurality of timing metrics according to the M data, M is less than N, and the step of generating a plurality of timing metrics further comprises:

selecting P data out of the N sampled data to generate at least a first timing metric, the P data comprising a K th data and a K th +2) data; and

selecting Q data out of the N sampled data to generate at least a second timing metric the Q data comprising a (K th +1) data and a K th +3) data;

wherein P, Q, K, and M are positive integers, and M is equal to or greater than 2;

changing the sign of the first timing metric; and

correcting the symbol timing according to the sign changed first timing metric and the second timing metric;

wherein a symbol period averagely corresponds to more than one timing metric.

12. The method of claim 11 , further comprising:

performing an operation on the sign changed first timing metric and the second timing metric to generating an operating result, and

correcting the symbol timing according to the operating result.