Who came up with variable twist wire?

As in what’s in use with CAT5, etc. I know they started using balanced back in the day of telegraphs to reduce cross-talk. Ball Labs probably starte dthe practice of twisting for reducing cross-talk even more as the requirement and bundle count increased. But, someone came up with using variable twist rates so you reduce the cross-talk even further.

Who/when? I find info on variable rate twist but nothing on the who/when.

Who came up with the right hand rule?

“Twisted pair cables were invented by Alexander Graham Bell in 1881”

He got the patent.



My suspicion is that the different pitch or twist rates came about somewhat organically as American Telephone and Telegraph and Western Electric were figuring out the science (and a bit of art) of running miles-long cables with dozens or hundreds of pairs and getting usable voice quality from them.

I came across a conference report from 1887 that indicates AT&T and WE tried swapping pairs from one cable section to another on a run and found improved performance. Each voice circuit would also be moved from one internal bundle to another inside the cables so it wasn’t wrapped up alongside the same conversations for the entre run.

Keeping track of the pairs through all of those cross-connects must have been a nightmare.

Here’s the Google Patent link. When I look at the supplied drawing I notice that the wire pairs are at 90 and 45 degree angles to each other in order to maximize isolation. So, I’ll agree that the evolution of variable pitch twisted pair was an eventual solution. I still want to know though :slight_smile:

Any ways, here they mention to use regular and uniform twists.

Oh forgot the variable twist rate.

Patent US4873393 A
Publicatiedatum 10 okt 1989
Aanvraagdatum 21 maart 1988
Prioriteitsdatum 21 maart 1988
Harold W. Friesen, Wendell G. Nutt
American Telephone And Telegraph Company, At&T Bell Laboratories

Thanks! Here is a link to that patent and when I look at the citations I find another, earlier, patent from 1969 specifically about using variable twist wire to reduce cross-talk. That’s the important part, variable twist for the use of reducing cross-talk.

Publication number US3546357 A
Publication type Grant
Publication date Dec 8, 1970
Inventors Macpherson William F, Windeler Alfred S
Original Assignee Bell Telephone Labor Inc

That 1969 patent isn’t the earliest, either, since it reads:

So it was already “routine” in 1969.