I'm looking for experts/companies/laboratories who are working on cables and wires.
Caracteristics : low voltage/modulated impedance
Objective : creating or buying (!) a cable/wire able to process simultaneous sources/data/information merging lan standards and wireless technologies.
Applications : not only computers but telecommunications, domotics
Any other informations are welcome (patents, associations, etc.)
Modulated impedance? This is a thing from control systems, not telecommunications. By definition any wire will have fixed impedance value, varying only because of production or installation issues.
Nice and rare term "Domotics". I like it, but it has its own Usenet group: alt.home.automation We keep its archive here if you are interested:
Google.com and, also: United States Patent and Trademark Office at
For twisted pair the impedance is sensitive to the spacing between the two wires. Variations in the spacing lead to impedance variations, which affect attenuation and crosstalk.
There are UTP cables where the two are bonded, much like a small model of ordinary lamp cord. That keeps the spacing much more constant, especially if the cable is flexed or bent too sharp.
Yes, it really is modulated impedance.
-- glen
i Glen,
The changes in impedance that you correctly identified are only by-products of production and installation specifics. After the cable's design is approved at the manufacturing plant, there is no way to affect the impedance in any useful way. Any changes are always random, unpredictable and, at large, undesirable.
Modulated impedance would mean that by deliberately changing the impedance in a certain way, some useful job is done or some useful information is conveyed. Much like in control systems where, by changing impedance of the system you control, you can change the way it responds to changes in the environment.
So, with that said, I would call the cabling system's impedance "fluctuating" rather than "modulated"
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