What kind of screwy cables are those ? 1kHz has NOTHING to do with their
Here we use CW1308.
And why the heck do you think ADSL is based around an assumption of
typical 100 ohm charactistic cable / line impedance ?
Speaking of cretins!
The chart is from Bell System documentation (which I cited in
another article). If you think the frequency has nothing to do
with the characteristic impedance, argue with Bell Labs.
ADSL is based on 100 Ohm impedance for very good reasons. One
of them being the frequencies used...
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson
Ukpeagvik (Barrow, Alaska) firstname.lastname@example.org
Course there are misunderstandings and some terminology shift in
broadcast/telecoms and all related to the way various operators used to
and now do things etc at different times..
But its all good for a slanging match;)...
Impedance for an un-loaded pair varies with frequency. So at DSL
frequencies the impedance
is 100 to 110 Ohms. But for telephone use They preferred to use loaded
pairs and they were
designed to be 900 Ohms. And the phone should be a reasonable match to
the line to minimize refections which bother the users as echoes
The transformers in some sets was not an isolation transformer but a
hybrid and matching transformer. The carbon mic. used in the old phones
was powered from the line. And many
of the newer phones derive power from the line. So isolation can't be used.
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