[SI-LIST] Re: Differential signaling history
- From: "Zhou, Xingling (Mick)" <xlzhou@xxxxxxxxx>
- To: "'Ingraham, Andrew'" <Andrew.Ingraham@xxxxxx>,"Zhou, Xingling (Mick)" <xlzhou@xxxxxxxxx>
- Date: Wed, 5 Mar 2003 11:18:01 -0500
I think we are in the right direction. Any documents would be helpful to
understand it. Did they resolve the issue right away ? Or any other failed
tries etc. ? May be reducing noise is the motivation, must be. But how (the
solution) is another problem) ? From our point of view, the reasons are not
more than explanations. Did the pioneers know the good "reasons" as we do ?
I doubt. A typical example is that Edison did know all the sciences/reasons
behind his great inventions in many cases.
Still rough thoughts. Fortunately, we can keep designing differential pairs
(even better) without knowing the history at all !
Mick
-----Original Message-----
From: Ingraham, Andrew [mailto:Andrew.Ingraham@xxxxxx]
Sent: Wednesday, March 05, 2003 10:46 AM
To: xlzhou@xxxxxxxxx
Cc: si-list
Subject: RE: [SI-LIST] Differential signaling history
For that, you probably need to go back to the beginnings of the telephone.
Perhaps even the telegraph.
Single-ended phone circuits over long distances with a common "ground"
simply don't work. Far too much noise.
You need two wires to complete a circuit, and if neither one is ground, you
logically get a differential pair.
They realized back then that the pairs had to be kept well balanced. On old
open wire telephone lines that used to run down highways or alongside train
tracks, you'd see that they periodically swapped the wires in each pair (at
prescribed intervals) to maintain balance and cancel coupling between all
the pairs and from other sources.
Regards,
Andy
> I am curious about the history of differential signaling. We can easily =
> explain in various versions intuitively or mathematically the benefits =
> of differential signaling now either in circuit design (differential =
> amplifiers/also called differential pair, for example) or in PCB design =
> (differential pairs), even in cable designs. What the first guys who =
> came up this idea originally thought and how/when they implemented the =
> idea ? etc.
>
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