Re: Single Cat5e for Computer Network & Telephone?

Watson A.Name - "Watt Sun, the Dark Remover" wrote:

>> How does a cable take a signal below 4 kHz, and convert it to
> something in
>> the range of several MHz?
>
> The last time I checked, the cable creates its own energy by acting as
> an antenna. Nearby radio stations can induce signals that are strong
> enough to interfere with data signals. This is less true for well
> balanced cables, but it can still happen. The world's not perfect,
> unfortunately, as theory would have you believe.

That's not creating energy. It's merely conducting energy from another
source, such as a radio station. Then again, if that was a problem, it
wouldn't likely require the presence of a phone line in the CAT5 cable to
make it one.

>
> Corrosion and/or rust on a contact can cause rectification and detection
> of signals, making them mix and/or change frequency. Again, the world's
> not perfect, unfortunately, as theory would have you believe.

Yes, as I mentioned earlier, corroded connections can generate harmonics,
but they still cannot create energy. It can, through the generation of
harmonics, affect the frequency distribution of the energy, but not create
more than there was to begin with. And again, the harmonics will have
reduced amplitude with harmonic order. It's been a long time since I've
looked at the harmonic distribution of a perfect half wave rectifier (the
best you can get with a perfect diode), so I don't recall the exact
details. However, here's some info about harmonic distribution, in both
full and half wave rectifiers. Don't forget, corrosion is not likely to
form a "perfect" rectifier, so the amount of harmonic energy will be even
less.

http://www.dranetz-bmi.com/pdf/harmonicspart3.pdf

I've never claimed a perfect world, but some people seem to be making some
extraordinary claims about potential problems, without examining the real
world facts, that must follow the laws of physics. Incidentally, a phone
line that generates significant levels of harmonics, does so by creating
significant levels of distortion in the desired signal. Such a line would
not go unnoticed for long.


.

Relevant Pages

  • Re: What are the physics of timber in music ?
    ... >> harmonics, ... How would an amplifier know, ... > which cause further distortions of signals with a large dynamic ... "Solid core speaker cables tend to cut off the leading and trailing edges of musical notes and produce a slightly lean bass sound" ...
    (sci.physics)
  • Re: THD Simulation
    ... THD is the measure of the amount of energy in the harmonics relative ... So from your DFT, choose the first N harmonics of interest, let say 20 ... harmonics of your signals, which happens when the time window of the ...
    (comp.cad.cadence)
  • Re: Single Cat5e for Computer Network & Telephone?
    ... >>> ethernet signaling is in the several MHz range. ... >> Harmonics aren't the only way to generate energy. ... Nearby radio stations can induce signals that are strong ... balanced cables, ...
    (comp.dcom.cabling)
  • Re: RS485 is bidirectional does it mean it is fullduplex?
    ... the receiver typically cannot tolerate a common mode ... not to mention other noise sources. ... The RS-485 signals are carried on a cable. ... If he had significant experience with comm cables, ...
    (comp.arch.embedded)
  • Re: Is 50m too far....
    ... Cable attenuates the high frequency signals according as its length. ... "zone 2 Sky dish". ... line amp, if only because an amp with 'slope' will equalise the signal ... with long cables will still have problems.If you want a complete solution ...
    (uk.tech.digital-tv)