[elektro-etc] telefonzsinor

[Moczik Gabor]

potyo wrote:
> Tudtommal a telefonhálózat hullámimpedanciája 600ohm, míg az UTP 100 ohmos.

Az audió frekvenciákon 600ohm, de a DSL-re meg 100ohm. Elég nagy 
frekvencia átfogás van, ezért nem lehet pontosan ennyi, de erre vannak 
az eszközök tervezve.


"The voice telephone system is matched to 600 ohm (or close to it) 
impedance at voice frequencies. ADSL technology operates between 26KHz 
and 1.1 MHz and is designed for around 100 ohms impedance. Because the 
two frequency spectrums do not overlap, it follows that both data and 
voice can be present at the same time on a single pair of copper wire. 
The different impedances have hostorical and technical reasons. The 
impedance of telephoen wiring is typically around 100-120 ohms at the 
frequencies ADSL system uses. The cable impedance is somewhat higher at 
voice frequency range, considerably higher than 100 ohms, and where 
where historical 600 ohms impedance comes to picture (cable might not be 
exactly 600 ohms for voice, but that's what devices are designed for)."


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