Analog video signal transmission over twisted-pair wires

• US 20060069829A1
• Filed: 09/28/2005
• Published: 03/30/2006
• Est. Priority Date: 09/28/2004
• Status: Active Grant

• Current Assignee: ClearCube Technology Incorporated
• Original Assignee: ClearCube Technology Incorporated
• Inventors: Thornton, Barry W.
• Granted Patent: US 8,074,255 B2
• Time in Patent Office: Days
• US Class Current: 710/106
• CPC Class Codes: H04N 1/648 Transmitting or storing the primary (additive or subtractive) colour signals; Compression thereof H04N1/642 - H04N1/646 take precedence
• CPC Class Codes: H04N 9/67 for matrixing camera processing pipelines for matrixing of colour signals H04N23/85

Abstract

A video transmitting system may be configured to transmit, over extended length twisted-pair cables, video signals encoded in the Y/C video space. The system may comprise a source of RGB computer video signals. A video transmitter may be operable to convert the RGB video signals into a balanced luminance signal and a respective pair of balanced color difference signals. The video transmitting system may be further configured to transmit the balanced luminance signal and the pair of balanced color difference signals over respective extended length twisted-pair cables. The luminance signal may be transmitted over a non time-corrected cable in order to retain bandwidth, while the color difference signals may be transmitted over time-corrected cables, thereby reducing the visual degradation of the signals.

Claims

1. A video transmission system for transmitting computer video signals, the system comprising:

a source of computer video signals including red, green, and blue video signals; and

a video transmitter comprising;

a video encoder operable to receive the red, green and blue video signals and convert the red, green and blue video signals into a single-ended luminance signal and a pair of single-ended color difference signals; and

a converter configured to receive the single-ended luminance signal and the pair of single-ended color difference signals, and operable to generate a balanced luminance signal from the single-ended luminance signal and a respective pair of balanced color difference signals from the pair of single-ended color difference signals; and

a plurality of twisted-pair conductors, one end of each of the plurality of twisted-pair conductors configured to couple to the converter, wherein the video transmitter is operable to transmit the balanced luminance signal over a first one of the plurality of twisted-pair conductors, and to transmit the pair of balanced color difference signals over respective second and third ones of the plurality of twisted-pair conductors;

wherein a length of the first one of the plurality of twisted-pair conductors is shorter than a respective length of the respective second and third ones of the plurality of twisted-pair conductors.

2. The system of claim 1, wherein the length of the first one of the plurality of twisted-pair conductors exceeds 100 ft.

3. The system of claim 1, wherein the luminance signal comprises a sum of the red, green, and blue video signals.

4. The system of claim 3, wherein one of the pair of single-ended color difference signals comprises an inverse of a sum of the green video signal and the blue video signal, and the other of the pair of single-ended color difference signals comprises an inverse of a sum of the green video signal and the red video signal.

5. The system of claim 3, wherein one of the pair of single-ended color difference signals comprises an inverse of a sum of the blue video signal and the green video signal, and the other of the pair of single-ended color difference signals comprises an inverse of a sum of the blue video signal and the red video signal.

6. The system of claim 3, wherein one of the pair of single-ended color difference signals comprises an inverse of a sum of the red video signal and the green video signal, and the other of the pair of single-ended color difference signals comprises an inverse of a sum of the red video signal and the blue video signal.

7. The system of claim 1, further comprising:

a video receiver configured to couple to the other end of each of the plurality of twisted-pair conductors and comprising;

a converter configured to receive the balanced luminance signal and generate the single-ended luminance signal from the balanced luminance signal, and further configured to receive the respective pair of balanced color difference signals and generate the pair of single-ended color difference signals from the respective pair of balanced color difference signals; and

a video decoder configured to receive the single-ended luminance signal and the pair of single-ended color difference signals, and operable to convert the single-ended luminance signal and the pair of single-ended color difference signals into the red, green and blue video signals.

8. The system of claim 7, wherein the video decoder is operable to provide the red, green and blue video signals to a computer monitor.

9. A method for transmitting computer video signals, the method comprising:

receiving red, green, and blue video signals;

converting the red, green and blue video signals into a single-ended luminance signal and a pair of single-ended color difference signals;

generating a balanced luminance signal from the single-ended luminance signal;

generating a respective pair of balanced color difference signals from the pair of single-ended color difference signals;

transmitting the balanced luminance signal over a first one of a plurality of twisted-pair conductors; and

transmitting the respective pair of balanced color difference signals over respective second and third ones of the plurality of twisted-pair conductors;

wherein a length of the first one of the plurality of twisted-pair conductors is shorter than a respective length of the respective second and third ones of the plurality of twisted-pair conductors, thereby retaining bandwidth and reducing visual degradation of the transmitted balanced luminance signal and the transmitted respective pair of balanced color difference signals.

10. The method of claim 9, wherein the length of the first one of the plurality of twisted-pair conductors exceeds 100 ft.

11. The method of claim 9, wherein said converting the red, green and blue video signals comprises summing the red, green and blue video signals to obtain the single-ended luminance signal.

12. The method of claim 11, wherein said converting the red, green and blue video signals further comprises:

summing the green video signal and the blue video signal to obtain a first combined signal;

inverting the combined signal to obtain one of the pair of single-ended color difference signals;

summing the green video signal and the red video signal to obtain a second combined signal; and

inverting the second combined signal to obtain the other of the pair of single-ended color difference signals.

13. The method of claim 11, wherein said converting the red, green and blue video signals further comprises:

summing the blue video signal and the green video signal to obtain a first combined signal;

inverting the combined signal to obtain one of the pair of single-ended color difference signals;

summing the blue video signal and the red video signal to obtain a second combined signal; and

inverting the second combined signal to obtain the other of the pair of single-ended color difference signals.

14. The method of claim 11, wherein said converting the red, green and blue video signals further comprises:

summing the red video signal and the green video signal to obtain a first combined signal;

inverting the combined signal to obtain one of the pair of single-ended color difference signals;

summing the red video signal and the blue video signal to obtain a second combined signal; and

inverting the second combined signal to obtain the other of the pair of single-ended color difference signals.

15. The method of claim 9 further comprising:

receiving the balanced luminance signal over the first one of the plurality of twisted-pair conductors;

generating the single-ended luminance signal from the balanced luminance signal;

receiving the respective pair of balanced color difference signals over the respective second and third ones of the plurality of twisted-pair conductors;

generating the pair of single-ended color difference signals from the respective pair of balanced color difference signals; and

converting the single-ended luminance signal and the pair of single-ended color difference signals into the red, green and blue video signals.

16. The method of claim 15, wherein said converting the single-ended luminance signal and the pair of single-ended color difference signals into the red, green and blue video signals comprises:

summing the single-ended luminance signal and one of the pair of single-ended color difference signal to obtain one of the red, green and blue video signals;

summing the single-ended luminance signal and the other of the pair of single-ended color difference signal to obtain one of the remaining two of the red, green and blue video signals;

inverting each of the pair of single-ended color difference signals, and summing the luminance signal and the inverted pair of single-ended color difference signals to obtain the remaining one of the red, green and blue video signals.

17. A video transmission system for transmitting computer video signals, the system comprising:

a source of computer video signals including red, green, and blue video signals; and

a video transmitter comprising;

a video encoder operable to convert the red, green and blue video signals into a single-ended luminance signal and a pair of single-ended color difference signals;

a quadrature modulator configured to receive the pair of single-ended color difference signals, and operable to generate a single-ended chrominance signal from the pair of single-ended color difference signals; and

a converter configured to receive the single-ended luminance signal and the single-ended chrominance signal, and operable to generate a balanced luminance signal from the single-ended luminance signal and a balanced chrominance signal from the single-ended chrominance signal; and

a pair of twisted-pair conductors, one end of each of the pair of twisted-pair conductors configured to couple to the converter, wherein the video transmitter is operable to transmit the balanced luminance signal over one of the pair of twisted-pair conductors, and to transmit the balanced chrominance signal over the other of the pair of twisted-pair conductors.

18. The system of claim 17, wherein a length of each of the pair of twisted-pair conductors exceeds 100 feet.

19. The system of claim 17, further comprising:

a video receiver configured to couple to the other end of each of the pair of twisted-pair conductors and comprising;

a converter configured to receive the balanced luminance signal and generate the single-ended luminance signal from the balanced luminance signal, and further configured to receive the balanced chrominance signal and generate the single-ended chrominance signal from the balanced chrominance signal;

a quadrature demodulator configured to receive the balanced chrominance signal, and operable to generate the pair of single-ended color difference signals from the balanced chrominance signal; and

a video decoder configured to receive the single-ended luminance signal and the pair of single-ended color difference signals, and operable to convert the single-ended luminance signal and the pair of single-ended color difference signals into the red, green and blue video signals.

20. The system of claim 19, wherein the video decoder is operable to provide the red, green and blue video signals to a computer monitor.

21. A system comprising:

a computing system operable to generate computer video signals including red, green, and blue video signals;

a transmitter extender device configured to couple to the central processing unit and operable to receive the red, green and blue video signals and convert the red, green and blue video signals into a balanced luminance signal and a respective pair of balanced color difference signals;

a plurality of twisted-pair conductors, one end of each of the plurality of twisted-pair conductors configured to couple to the transmitter extender device, wherein the video transmitter is operable to transmit the balanced luminance signal over a first one of the plurality of twisted-pair conductors, and to transmit the pair of balanced color difference signals over respective second and third ones of the plurality of twisted-pair conductors;

a receiving extender device configured to couple to the transmitter extender device via the other end of each of the plurality of twisted-pair conductors, and operable to receive the balanced luminance signal and the respective pair of balanced color difference signals and generate the red, green and blue video signals; and

a display device, wherein the receiving extender device is operable to provide the red, green and blue video signals to the display device;

wherein a length of the first one of the plurality of twisted-pair conductors is shorter than a respective length of the respective second and third ones of the plurality of twisted-pair conductors.

22. The system of claim 21,

wherein the transmitter extender device comprises:

a video encoder operable to receive the red, green and blue video signals and convert the red, green and blue video signals into a single-ended luminance signal and a pair of single-ended color difference signals; and

a transmitter converter configured to receive the single-ended luminance signal and the pair of single-ended color difference signals, and operable to generate a balanced luminance signal from the single-ended luminance signal and a respective pair of balanced color difference signals from the pair of single-ended color difference signals;

wherein the receiving extender device comprises;

a receiver converter configured to receive the balanced luminance signal and generate the single-ended luminance signal from the balanced luminance signal, and further configured to receive the respective pair of balanced color difference signals and generate the pair of single-ended color difference signals from the respective pair of balanced color difference signals; and

a video decoder configured to receive the single-ended luminance signal and the pair of single-ended color difference signals, and operable to convert the single-ended luminance signal and the pair of single-ended color difference signals into the red, green and blue video signals.

23. The computing system of claim 21, further comprising a keyboard and a mouse, each configured to couple to the receiving extender device.