Composite color frame identifier system and method

1. A color frame identifier circuit, comprising:

a pseudo-subcarrier generator circuit configured to receive a reference clock and a first reference signal and generate a pseudo-subcarrier signal at a pseudo-subcarrier frequency based on the reference clock and at a set phase relative to the first reference signal;

a color burst slicer circuit configured to slice a color burst signal of a composite video signal at a reference voltage and generate a sliced burst signal;

a correlation circuit configured to receive the sliced burst signal and the pseudo-subcarrier signal and generate a burst comparison value for each sliced burst signal; and

a processing circuit configured to receive the burst comparison value for each sliced burst signal and generate a color frame identifier signal based on the sliced burst signals;

wherein the first reference signal comprises a horizontal sync pulse of a composite video signal comprising a plurality of lines defining a video frame, and the pseudo-subcarrier generator circuit generates the pseudo-subcarrier signal at the set phase relative to the horizontal sync pulse.

2. The color frame identifier circuit of claim 1 , further comprising:

a window generator circuit configured to receive the reference clock and the first reference signal and generate a window signal relative to the first reference signal.

3. The color frame identifier circuit of claim 2 , wherein the window generator circuit is further configured to receive a second reference signal and generate the window signal additionally relative to the second reference signal.

4. The color frame identifier circuit of claim 3 , wherein the first reference signal comprises a horizontal sync pulse of a composite video signal comprising a plurality of lines that define a video frame, and the second reference signal comprises a vertical sync pulse of the composite video signal.

5. The color frame identifier circuit of claim 4 , wherein the window generator is further configured to generate the window signal for at least one selected line in each video frame.

6. The color frame identifier circuit of claim 5 , wherein the composite video signal comprises an NTSC television signal.

7. The color frame identifier circuit of claim 5 , wherein the composite video signal comprises a PAL television signal.

8. The color frame identifier circuit of claim 1 , wherein the pseudo-subcarrier generator circuit is further configured to select the pseudo-subcarrier frequency by setting the pseudo-subcarrier frequency to an approximate frequency of the color burst signal.

9. The color frame identifier circuit of claim 8 , wherein the pseudo-subcarrier generator circuit comprises a ring oscillator.

10. The color frame identifier circuit of claim 1 , wherein the correlation circuit comprises an exclusive OR gate configured to receive the pseudo-subcarrier signal and the sliced burst signal as input.

11. The color frame identifier circuit of claim 10 , wherein the correlation circuit further comprises an accumulator configured to receive the output of the exclusive OR gate and generate a corresponding output.

12. The color frame identifier circuit of claim 1 , wherein the pseudo-subcarrier generator circuit generates the pseudo-subcarrier signal at the set phase relative to the horizontal sync pulse by selecting a first set phase a first line in the video frame and a second set phase for a second line in the video frame.

13. The color frame identifier circuit of claim 4 , wherein the pseudo-subcarrier generator circuit generates the pseudo-subcarrier signal at the set phase relative to the horizontal sync pulse by selecting a first set phase for a first line in the video frame and a second set phase for a second line in the video frame.

14. The color frame identifier circuit of claim 1 , wherein the reference clock is a 27 MHz reference clock.

15. A method of processing a television video signal, comprising:

generating a pseudo-subcarrier signal at a pseudo-subcarrier frequency based on a reference clock and at a set phase relative to a first reference signal in the video signal;

slicing a color burst signal of the television video signal to generate a sliced burst signal;

comparing the sliced burst signal and the pseudo-subcarrier signal;

generating a comparison signal for each comparison of the sliced burst signal and the pseudo-subcarrier signal; and

generating a color frame identifier signal based on the generated comparison signals;

wherein generating a pseudo-subcarrier signal at a pseudo-subcarrier frequency based on a reference clock and at a set phase relative to a first reference signal in the video signal comprises:

setting the pseudo-subcarrier signal at a first set phase a first line in the video frame relative to the first reference signal: and

setting the pseudo-subcarrier signal at a second set phase for a second line in the video frame relative to the first reference signal;

wherein the first reference signal comprises a horizontal sync pulse.

16. The method of claim 15 , further comprising:

generating a window signal relative to the first reference signal; and

comparing the sliced burst signal and the pseudo-subcarrier signal only during the window signal.

17. The method of claim 16 , wherein generating a window signal relative to the first reference signal comprises generating the window signal for a selected line in a video frame for each successive video frame.

18. A color frame identifier circuit, comprising:

means for generating a pseudo-subcarrier signal at a pseudo-subcarrier frequency based on a reference clock and at a set phase relative to a first reference signal in the video signal;

means for slicing a color burst signal of the television video signal to generate a sliced burst signal;

means for comparing the sliced burst signal and the pseudo-subcarrier signal;

means for generating a comparison signal for each comparison of the sliced burst signal and the pseudo-subcarrier signal; and

means for generating a color frame identifier signal based on the generated comparison signals;

wherein the means for generating a pseudo-subcarrier signal at a pseudo-subcarrier frequency based on a reference clock and at a set phase relative to a first reference signal in the video signal comprises:

means for setting the pseudo-subcarrier signal at a first set phase a first line in the video frame relative to the first reference signal; and

means for setting the pseudo-subcarrier signal at a second set phase for a second line in the video frame relative to the first reference signal;

wherein the first reference signal comprises a horizontal sync pulse.

19. The color frame identifier circuit of claim 18 , further comprising:

means for generating a window signal relative to the first reference signal.