Cable apparatus for minimizing skew delay of analog signals and cross-talk from digital signals and method of making same

• US 20050199416A1
• Filed: 03/12/2004
• Published: 09/15/2005
• Est. Priority Date: 03/12/2004
• Status: Active Grant

• Current Assignee: RGB Systems Incorporated
• Original Assignee: RGB Systems Incorporated
• Inventors: Geil, Jacob, Raheja, Ash, Somers, Steve L.
• Granted Patent: US 7,078,626 B2
• Time in Patent Office: Days
• US Class Current: 174/113.00R
• CPC Class Codes: H01B 11/02 Cables with twisted pairs or quads

Abstract

An unshielded twisted pair (UTP) cable minimizes skew delay of analog signals by enforcing a common electrical length among twisted pairs that carry those analog signals. By applying a different lay length and lay direction to the twisted pair that carries the digital signal, cross-talk from the digital signal onto the analog signals is minimized. The twisted pairs for carrying the analog signals may be bundled together, with the twisted pair for carrying the digital signal placed alongside the bundled pairs during the final extraction process, during which the outer insulator is formed around all of the pairs. The bundled pairs may be used for the transmission of analog video signals (e.g., R, G and B), with the remaining pair used for transmission of digital control or digital audio signals.

Claims

1. A cable comprising:

a plurality of first twisted pairs of conductors having a first lay direction and a first lay length, wherein said plurality of first twisted pairs are twisted together in said first lay direction to form a bundle, wherein said plurality comprises at least three; and

a second twisted pair of conductors having a second lay direction and a second lay length, wherein said second lay direction is opposite to said first lay direction and wherein said second lay length is different than said first lay length; and

an outer jacket encompassing said bundle and said second twisted pair, wherein said second twisted pair is laid in parallel and not twisted together with said bundle.

2. The cable of claim 1, wherein said second lay length is longer than said first lay length.

3. The cable of claim 1, wherein said first lay direction is clockwise and said second lay direction is counterclockwise.

4. The cable of claim 1, wherein said first lay direction is counterclockwise and said second lay direction is clockwise.

5. The cable of claim 1, wherein said bundle is twisted in said first lay direction.

6. The cable of claim 1, wherein said plurality of first twisted pairs are of substantially equivalent electrical length.

7. The cable of claim 6, wherein said outer jacket comprises markings for cutting locations associated with minimum skew.

8. The cable of claim 1, further comprising a third twisted pair laid in parallel with said bundle and encompassed by said outer jacket.

9. The cable of claim 1, wherein said cable has a tear drop shaped cross-section.

10. A UTP cable comprising:

a bundle of twisted pairs, said bundle comprising;

a first twisted pair;

a second twisted pair; and

a third twisted pair;

wherein said first twisted pair, said second twisted pair and said third twisted pair have a common lay length and a common lay direction, and are twisted together in said common lay direction to form said bundle;

a fourth twisted pair laid in parallel with and outside a perimeter of said bundle, said fourth twisted pair having a lay length different from said common lay length and a lay direction opposite to said common lay direction.

11. The cable of claim 10, further comprising an outer jacket encompassing said bundle and said fourth twisted pair.

12. The cable of claim 10, wherein said bundle is twisted in said common lay direction.

13. The cable of claim 10, wherein said cable has a tear drop shaped cross-section.

14. A method for making a cable comprising:

twisting together a plurality of twisted pairs into a bundle in a first common lay direction, each of said plurality of twisted pairs having said common lay direction and a common lay length;

laying an additional twisted pair in parallel with said bundle, said additional twisted pair having a second lay direction that is opposite to said common lay direction and a second lay length that differs from said common lay length;

encompassing said bundle and said additional twisted pair in an outer jacket.

15. The method of claim 14, wherein said encompassing comprises feeding said bundle and said additional twisted pair in parallel through an extruder.

16. The method of claim 14, wherein said twisting is peformed in said common lay direction.

17. The method of claim 14, wherein said additional twisted pair has a lay length that is longer than said common lay length.

18. The method of claim 14 wherein said plurality is three.

19. The method of claim 14, wherein said common lay direction is clockwise.

20. The method of claim 14, wherein said common lay direction is counterclockwise.