COMMUNICATION RECEIVER AND A RECEIVING METHOD

• US 20120170693A1
• Filed: 01/05/2011
• Published: 07/05/2012
• Est. Priority Date: 01/05/2011
• Status: Active Grant

• Current Assignee: Himax Media Solutions, Inc. (Himax Technologies Incorporated)
• Original Assignee: Himax Media Solutions, Inc. (Himax Technologies Incorporated)
• Inventors: HUNG, Cheng-Hsi, Kao, Shiang-Lun
• Granted Patent: US 8,488,732 B2
• Time in Patent Office: Days
• US Class Current: 375/342
• CPC Class Codes: H04L 25/069 by detecting edges or zero crossings
• CPC Class Codes: H04L 7/0334 Processing of samples having at least three levels, e.g. soft decisions
• CPC Class Codes: H04L 7/046 using a dotting sequence

Abstract

A communication receiver and a receiving method are disclosed. An analog front-end device samples a receiving signal and generates a sampled signal. A signal detector detects presence of the receiving signal according to the sampled signal. A symbol timing recovery (STR) unit determines an optimal symbol sampling point according to a zero-crossing point of the sampled signal when the receiving signal is present, and then generates a recovered symbol based on an optimally chosen sampled value according to the optimal symbol sampling point.

Claims

1. A communication receiver, comprising:

an analog front-end device configured to sample a receiving signal and generate a sampled signal;

a signal detector configured to detect presence of the receiving signal according to the sampled signal; and

a symbol timing recovery (STR) unit configured to determine an optimal symbol sampling point according to a zero-crossing point of the sampled signal when the receiving signal is present, the STR unit generating a recovered symbol based on an optimally chosen sampled value according to the optimal symbol sampling point.

2. The communication receiver of claim 1, wherein the analog front-end device is a slicer configured to map a sampled value of the receiving signal greater than a positive threshold to “

1”

, the sampled value less than a negative threshold to “

−

1”

, and to “

0”

otherwise.

3. The communication receiver of claim 1, wherein the signal detector generates an asserted flag when the receiving signal is present, otherwise generates a non-asserted flag.

4. The communication receiver of claim 3, wherein the signal detector initiates an auto-negotiation session when the flag toggles between assertion and non-assertion at a frequency exceeding a predetermined value.

5. The communication receiver of claim 3, wherein the signal detector outputs the asserted flag when both a positive pulse and a negative pulse are detected.

6. The communication receiver of claim 5, wherein the positive pulse is either a positive wide pulse having a width of a symbol period or a positive narrow pulse having a width of a half symbol period;

and the negative pulse is either a negative wide pulse having a width of the symbol period or a negative narrow pulse having a width of the half symbol period.

7. The communication receiver of claim 1, further comprising:

a decoder configured to decode the recovered symbol into a decoded symbol.

8. The communication receiver of claim 7, wherein the decoder is a Manchester decoder that adopts Manchester coding, in which each data bit has at least one transition.

9. The communication receiver of claim 1, wherein the STR unit comprises a free-run counter configured to denote sequence of the sampled signal in order within a half symbol duration.

10. The communication receiver of claim 1, further comprising a storage device configured to store the sampled signal.

11. A communication receiving method, comprising:

sampling a receiving signal to generate a sampled signal;

detecting presence of the receiving signal according to the sampled signal;

determining an optimal symbol sampling point according to a zero-crossing point of the sampled signal when the receiving signal is present; and

generating a recovered symbol based on an optimally chosen sampled value according to the optimal symbol sampling point.

12. The method of claim 11, wherein the sampled signal is generated by mapping a sampled value of the receiving signal greater than a positive threshold to “

1”

, the sampled value less than a negative threshold to “

−

1”

, and to “

0”

otherwise.

13. The method of claim 11, further comprising a step of generating an asserted flag when the receiving signal is present, otherwise generating a non-asserted flag.

14. The method of claim 13, further comprising a step of performing an auto-negotiation session when the flag toggles between assertion and non-assertion at a frequency exceeding a predetermined value.

15. The method of claim 13, wherein the flag is asserted when both a positive pulse and a negative pulse are detected.

16. The method of claim 15, wherein the positive pulse is either a positive wide pulse having a width of a symbol period or a positive narrow pulse having a width of a half symbol period;

and the negative pulse is either a negative wide pulse having a width of the symbol period or a negative narrow pulse having a width of the half symbol period.

17. The method of claim 11, further comprising a step of decoding the recovered symbol into a decoded symbol.

18. The method of claim 17, wherein the decoding step adopts Manchester coding, in which each data bit has at least one transition.

19. The method of claim 11, further comprising a step of storing the sampled signal.

20. The method of claim 11, wherein the optimal sampling point is determined, when a zero-crossing point is detected, according to difference between a free-run counting value and an index, wherein the free-run counting value denotes sequence of the sampled signal in order within a half symbol duration, and the index denotes the optimal symbol sampling point associated with the free-run counting value.

21. The method of claim 20, wherein the step of generating the recovered symbol comprises:

summing up at least one preceding sample value and at least one succeeding sample value of the sampled signal with a current sample value when the free-run counting value is equal to the index, thereby resulting in a sum value;

outputting “

0”

as the recovered symbol when the sum value is less than zero;

outputting “

1”

as the recovered symbol when the sum value is greater than zero; and

outputting a reversed recovered symbol that is reversed to the previous recovered symbol when the sum value is equal to zero.