Analog video signal transmission over twisted-pair wires

• US 8,074,255 B2
• Filed: 09/28/2005
• Issued: 12/06/2011
• Est. Priority Date: 09/28/2004
• Status: Active Grant

• Current Assignee: ClearCube Technology Incorporated
• Original Assignee: ClearCube Technology Incorporated
• Inventors: Thornton, Barry W.
• Primary Examiner(s): Nguyen, Kevin M
• Assistant Examiner(s): ALMEIDA, CORY A
• Application Number:
  US11/237,612
• Publication Number:
  US 20060069829A1
• Time in Patent Office: 2,260 Days
• Field of Search: 725/105, 725/148
• US Class Current: 725/148
• 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 analog red, green, and blue video signals; and

a video transmitter comprising;

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

a converter configured to receive the single-ended analog luminance signal and the pair of single-ended analog color difference signals, and further configured to generate a balanced analog luminance signal from the single-ended analog luminance signal and a respective pair of balanced analog color difference signals from the pair of single-ended analog 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 configured to transmit the balanced analog luminance signal over a first one of the plurality of twisted-pair conductors, and transmit the pair of balanced analog 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 single-ended analog luminance signal comprises a sum of the analog red, green, and blue video signals.

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

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

6. The system of claim 3, wherein one of the pair of single-ended analog color difference signals comprises an inverse of a sum of the analog red video signal and the analog green video signal, and the other of the pair of single-ended color difference signals comprises an inverse of a sum of the analog red video signal and the analog 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 analog luminance signal and generate the single-ended analog luminance signal from the balanced analog luminance signal, and further configured to receive the respective pair of balanced analog color difference signals and generate the pair of single-ended analog color difference signals from the respective pair of balanced analog color difference signals; and

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

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

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

receiving analog red, green, and blue video signals;

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

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

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

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

transmitting the respective pair of balanced analog 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 analog luminance signal and the transmitted respective pair of balanced analog 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 analog red, green and blue video signals comprises summing the analog red, green and blue video signals to obtain the single-ended analog luminance signal.

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

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

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

summing the analog green video signal and the analog 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 analog color difference signals.

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

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

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

summing the analog blue video signal and the analog 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 analog color difference signals.

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

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

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

summing the analog red video signal and the analog 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 analog color difference signals.

15. The method of claim 9 further comprising:

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

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

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

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

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

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

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

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

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

a video transmitter comprising;

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

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

a converter configured to receive the single-ended analog luminance signal and the single-ended analog chrominance signal, and further configured to generate a balanced analog luminance signal from the single-ended analog luminance signal and a balanced analog chrominance signal from the single-ended analog 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 configured to transmit the balanced analog luminance signal over one of the pair of twisted-pair conductors, and transmit the balanced analog 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 analog luminance signal and generate the single-ended analog luminance signal from the balanced analog luminance signal, and further configured to receive the balanced analog chrominance signal and generate the single-ended analog chrominance signal from the balanced analog chrominance signal;

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

a video decoder configured to

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

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

21. A system comprising:

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

a transmitter extender device configured to couple to the central processing unit and further configured to receive the analog red, green and blue video signals and convert the analog red, green and blue video signals into a balanced analog luminance signal and a respective pair of balanced analog 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 configured to transmit the balanced analog luminance signal over a first one of the plurality of twisted-pair conductors, and transmit the pair of balanced analog 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 further configured to receive the balanced analog luminance signal and the respective pair of balanced analog color difference signals and generate the analog red, green and blue video signals; and

a display device, wherein the receiving extender device is further configured to provide the analog 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 configured to receive the analog red, green and blue video signals and convert the analog red, green and blue video signals into a single-ended analog luminance signal and a pair of single-ended analog color difference signals; and

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

wherein the receiving extender device comprises;

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

a video decoder configured to receive the single-ended analog luminance signal and the pair of single-ended analog color difference signals, and further configured to convert the single-ended analog luminance signal and the pair of single-ended analog color difference signals into the analog 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.