ted
Joined: 12 Mar 2002
Posts: 118
Helped: 3
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 25 Mar 2003 3:08 |
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From whatis.techtarget.com :
"Crosstalk is a disturbance caused by the electric or magnetic fields of one telecommunication signal affecting a signal in an adjacent circuit. In an telephone circuit, crosstalk can result in your hearing part of a voice conversation from another circuit. The phenomenon that causes crosstalk is called electromagnetic interference (EMI). It can occur in microcircuits within computers and audio equipment as well as within network circuits. The term is also applied to optical signals that interfere with each other."
In other words, when a signal from one wire is transferred to another one in an unintended way, we call it "crosstalk"
Depending on the physical mechanism behind this transfer of signal, and the nature of resulted unwanted signal the names vary like "inductive crosstalk," "capacitive crosstalk," "near-end crosstalk," "far-end cosstalk" etc.
A rule of thumb is that in low impedance circuits the inductive one is usually more important and in high impedance circuits the capacitive one tends to dominate.
This theme is much related to EMC (ElectroMagnetic Compatibility) issues.
Typical countermeasures are (these are not in any particular order of importance or something):
*Shielding
*Distance between disturbing signal and disturbed signal
*Balanced signals (paired wires) where the disturbance is nullified from the Differential balanced signal by adding equally to both
*Avoiding common impedances on return ("ground") wires
*Reducing "loop area" (distance between signal and its return) in both disturbing and disturbed signal
Ted
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