System and method of adaptive timing estimation for horizontal overscan data

• US 6,704,058 B2
• Filed: 12/30/1999
• Issued: 03/09/2004
• Est. Priority Date: 12/30/1999
• Status: Expired due to Fees

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Ranta, Craig S.
• Primary Examiner(s): Miller, John
• Assistant Examiner(s): DESIR, JEAN WICEL
• Application Number:
  US09/476,177
• Publication Number:
  US 20030169367A1
• Time in Patent Office: 1,531 Days
• Field of Search: 348/465, 348/473, 348/476, 348/479, 348/468, 348/461, 348/460, 348/477, 348/478, 348/558
• US Class Current: 348/465
• CPC Class Codes: H04N 7/035 Circuits for the digital non-picture data signal, e.g. for slicing of the data signal, for regeneration of the data-clock signal, for error detection or correction of the data signal
• CPC Class Codes: H04N 7/085 the inserted signal being digital

Abstract

The adaptive timing module is configured for recovering data encoded in a field of a video signal, and further configured for counteracting horizontal phase or picture shift. An adaptive timing processor defines a timing window where the expected prescan portion video signal is expected to be in an encoded video signal. The timing window is divided into sub-portions with a set of sampling points. The adaptive timing processor conducts a sweeping operation over each sub-portion of the prescan portion of the encoded video signal for the presence of a pre-data encoding zone. When a pre-data encoding zone is detected, the adaptive timing processor stores the position of the sub-portion with the pre-data encoding zone, or sets a flag to indicate the presence of a pre-data encoding zone for that particular sub-portion in a particular field. After scanning one or more fields for the presence of a pre-data encoding zone, the adaptive timing processor uses the stored positions of pre-data encoding zones, or uses the flags indicating the pre-data encoding zones to determine a selected sampling point. The adaptive timing processor uses the selected sampling point to lock on to a location for decoding subsequent data in the encoded video signal.

Claims

1. A computer-readable medium having computer-executable instructions for carrying out a plurality of functions, including:

providing an adaptive timing processor for extracting digital data encoded in a horizontal overscan portion of a video signal, said adaptive timing processor performing the steps of;

conducting a sweeping operation through a timing search range within a plurality of scan lines over multiple fields of the video signal to detect a horizontal position within the scan lines associated with the digital data, the timing search range defining a plurality of sampling points within the horizontal overscan portion of the scan lines of the video signal, the sampling points corresponding to at least a first horizontal position at which the digital data are expected to be found based on a particular encoding scheme, and at least one additional horizontal position at which the digital data could be found due to a horizontal phase shift;

based on the sweeping operation, determining a desired horizontal detection position within the scan lines; and

detecting digital data encoded at the desired horizontal detection position of subsequent fields of the video signal.

2. The computer-readable medium of claim 1, wherein the timing search range comprises a range between about 8.8 and about 11.0 microseconds from a horizontal synchronization pulse or a timing signal that indicates the beginning of a scan line.

3. The computer-readable medium of claim 1, wherein the digital data encoded in the horizontal overscan portion of the video signal comprises a specific data sequence that indicates the beginning of a field of digital data.

4. The computer-readable medium of claim 1, wherein the digital data encoded in the horizontal overscan portion of the video signal comprise an intelligent signal detect word (ISDW).

5. The computer-readable medium of claim 3, wherein the step of determining a desired horizontal detection position within the scan lines comprises the step of comparing the desired horizontal position to a measured horizontal position.

6. The computer-readable medium of claim 4, wherein the step of determining a desired horizontal detection position within the scan lines comprises the step of comparing the digital data encoded in the horizontal overscan portion of the video signal to the ISDW.

7. The computer-readable medium of claim 1, wherein the step of conducting a sweeping operation through a timing search range within a plurality of scan lines over multiple fields of the video signal comprises the steps of:

dividing the timing search range into a plurality of equal portions, such that each portion includes at least one sampling point;

scanning each portion of the timing search range for digital data within the scan lines associated with the portion;

storing an indication of whether valid digital data was detected within each portion; and

determining a center point of the portions where valid data are detected.

8. The computer-readable medium of claim 7, wherein the step of determining a desired horizontal detection position within the scan lines comprises the step of locking onto the center point of the portions where valid data are detected.

9. The computer-readable medium of claim 1, wherein said adaptive timing processor repeats the step of detecting digital data encoded at the desired horizontal detection position of subsequent fields of the video signal until a reset condition is enabled.

10. The computer-readable medium of claim 9, wherein said adaptive timing processor further performs the step of responding to a reset condition, by repeating the steps of claim 1.

11. The computer-readable medium of claim 9, wherein the reset condition comprises the lapse of a predefined length of time.

12. The computer-readable medium of claim 9, wherein the reset condition comprises manually triggering a reset button.

13. In a display device for recovering data from a video signal divided into frames, wherein each frame comprises a plurality of horizontal scan lines consecutively illuminated on the display device, each scan line having a prescan portion including a pre-data encoding zone, a method for detecting encoded data in the pre-data encoding zone over a plurality of subsequent frames, comprising the steps of:

determining a set of sampling points within the prescan portion, the set of sampling points corresponding to at least a first sampling point at which the data are expected to be found based on a particular encoding scheme, and at least one additional sampling point at which the data could be found due to a horizontal phase shift;

sweeping over the set of sampling points within the prescan portion to identify encoded data; and

detecting the encoded data within the prescan portion.

14. In the display device of claim 13, said method further comprising the steps of:

determining a center point of the sampling points at which encoded data are identified;

locking onto the center point of the sampling points at which encoded data are identified; and

using the center point of the sampling points at which encoded data are identified for recovering the encoded data from the video signal.

15. In the display device of claim 13, the method wherein the encoded data comprises a predefined intelligent signal detect word (ISDW).

16. In the display device of claim 13, the method wherein the prescan portion comprises a range between about 8.8 and about 11.0 microseconds from a horizontal synchronization pulse or a timing signal that indicates the beginning of a scan line.

17. In the display device of claim 14, the method'"'"'s step of determining a center point of the sampling points comprising the steps of:

dividing the prescan portion into a plurality of equally sized sub-portions;

scanning each sub-portion to detect the presence of encoded data; and

storing a sampling position associated with the encoded data detected in each sub-portion.

18. In the display device of claim 13, said method further comprising the step of triggering a reset condition.

19. In the display device of claim 13, said method further comprising the step of repeating the step of detecting the encoded data within the prescan portion, until a reset condition is enabled.

20. In the display device of claim 19, said method further comprising the steps of repeating the steps of claim 19 in response to a reset condition.

21. In the display device of claim 18, the method wherein the reset condition comprises the lapse of a predefined length of time.

22. The display device of claim 18, wherein the reset condition comprises manually triggering a reset button.

23. A method for adjusting a decoder for horizontal phase shift while recovering digital data encoded in a horizontal overscan portion of a video signal, comprising the steps of:

conducting a sweeping operation through a timing search range within a plurality of scan lines over multiple fields of the video signal to detect encoded data within scan lines, the timing search range defining a plurality of sampling points within the horizontal overscan portion of the scan lines of the video signal, the sampling points corresponding to at least a first horizontal position at which the digital data are expected to be found based on a particular encoding scheme, and at least one additional horizontal position at which the digital data could be found due to horizontal phase shift;

based on results obtained from the sweeping operation, determining a desired horizontal detection position within the scan lines; and

detecting digital data encoded at the desired horizontal detection position of subsequent fields of the video signal.

24. The method of claim 23, wherein the timing search range comprises a range between about 8.8 and about 11.0 microseconds from a horizontal synchronization pulse or a timing signal that indicates a beginning of a scan line.

25. The method of claim 23, wherein the encoded data comprise a specific data sequence indicating a beginning of a field of digital data.

26. The method of claim 23, wherein the encoded data comprise an intelligent signal detect word (ISDW).

27. The method of claim 23, wherein the step of determining a desired horizontal detection position within the scan lines comprises the step of comparing a desired data sequence to a data sequence within the scan lines.

28. The method of claim 27, wherein the desired data sequence comprises an intelligent signal detect word (ISDW).

29. The method of claim 23, wherein the step of conducting a sweeping operation through a timing search range within a plurality of scan lines over multiple fields of the video signal further comprises the steps of:

dividing the timing search range into a plurality of equal portions such that each portion includes at least one sampling point;

scanning each portion of the timing search range for a horizontal position within the scan lines associated with the digital data;

storing an indication as to whether valid data were detected within each portion; and

determining a center point of the portions where valid data are detected.

30. The method of claim 29, wherein the step of determining a desired horizontal detection position within the scan lines comprises the step of locking onto the center point of the portions where the valid data are detected.

31. The method of claim 23, further comprising the step of repeating the step of detecting digital data encoded at the desired horizontal detection position of subsequent fields of the video signal, until a reset condition is enabled.

32. The method of claim 23, further comprising the step of repeating the steps of claim 23 in response to a reset signal.

33. The method of claim 31, wherein the reset condition comprises the lapse of a predetermined length of time.

34. The method of claim 31, wherein the reset condition comprises manually triggering a reset button.