SYSTEM AND METHOD OF ADAPTIVE TIMING ESTIMATION FOR HORIZONTAL OVERSCAN DATA

• US 20030169367A1
• Filed: 12/30/1999
• Published: 09/11/2003
• Est. Priority Date: 12/30/1999
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: RANTA, CRAIG
• Granted Patent: US 6,704,058 B2
• Time in Patent Office: Days
• 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 comprising:

an adaptive timing processor for extracting digital data encoded in a horizontal overscan portion of a video signal operable to perform the steps;

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;

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 8.8 and 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 horizontal overscan encoded data 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 horizontal overscan encoded data comprises 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 further comprises 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 further comprises comparing the decoded data to a predefined intelligent signal detect word (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 further comprises:

dividing the timing search range into a plurality of equal portions;

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

storing whether data was detected within each portion; and

determining a center point of the portions where valid datais detected.

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

9. The computer-readable medium of claim 1, 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.

10. The computer-readable medium of claim 9, further comprising the step of in response to a reset condition, the decoder will repeat the steps of claim 1.

11. The computer-readable medium of claim 7, wherein the reset condition comprises the elapse of a predefined length of time.

12. The computer-readable medium of claim 7, wherein the reset condition comprises manually triggering a reset button.

24. The method of claim 1, wherein the timing search range comprises a range between 8.8 and 11.0 microseconds from a horizontal synchronization pulse or a timing signal that indicates the beginning of a scan line.

25. The computer-readable medium of claim 1, wherein the encoded data comprises a specific data sequence that indicates the beginning of a field of digital data.

26. The computer-readable medium of claim 1, wherein the encoded data comprises an intelligent signal detect word (ISDW).

29. 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 further comprises:

dividing the timing search range into a plurality of equal portions;

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

storing whether valid data was detected within each portion; and

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

31. The computer-readable medium of claim 1, 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 computer-readable medium of claim 21, further comprising the step of in response to a reset condition, the decoder will repeat the steps of claim 1.

13. 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, wherein each scan line comprises a prescan portion comprising a pre-data encoding zone, wherein the display device scans the prescan portion for the presence of encoded data in the pre-data encoding zone over a plurality of subsequent frames, operable to perform the steps:

determining a set of sampling sub-portions within a prescan portion;

sweeping over the set of sampling points for the presence of encoded data; and

detecting encoded data within the prescan portion.

14. The display device of claim 13, further comprising the steps:

determining a center point of the sampling points;

locking onto the center point of the sampling points; and

using the center point of the sampling points for recovering subsequent data from the video signal.

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

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

17. The display device of claim 14, further comprising the steps, wherein the step of determining a center point of the sampling points further comprises:

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

scanning each sub-portion for the presence of encoded data;

detecting encoded data in a sub-portion; and

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

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

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

20. The display device of claim 19, further comprising the step of in response to a reset condition, the decoder will repeat the steps of claim 13.

21. The display device of claim 18, wherein the reset condition comprises the elapse of a predefined length of time.

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

27. The computer-readable medium of claim 15, wherein the step of determining a desired horizontal detection position within the scan lines further comprises comparing the desired data sequence to data sequence.

28. The computer-readable medium of claim 16, wherein the step of determining a desired horizontal detection position within the scan lines further comprises comparing the received data sequence to a stored intelligent signal detect word (ISDW).

30. The computer-readable medium of claim 19, wherein the step of determining a desired horizontal detection position within the scan lines further comprises locking onto the center point of the portions where valid data is detected.

33. The computer-readable medium of claim 21, wherein the reset condition comprises the elapse of a predetermined length of time.

34. The computer-readable medium of claim 21, wherein the reset condition comprises manually triggering a reset button.

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

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 the scan lines associated with the digital data;

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.