First post, by Jo22
This is an uncommon question perhaps, but why are cables for landlines still not shielded?
I fully understand that in the early days unshielded, maybe twisted cabling was cheap and totally sufficient for telephone lines, especially since most buildings had electrical lights, at best, and the RFI problems didn't really exist.
But since the days of acoustic couplers, ISDN in the early 80s and especially DSL in the 90s,
mustn't it have been clear that noise is a problem?
Why didn't telephone companies slowly start to use shielded cables, say cheap coaxial microphone cables?
I mean, DSL is a common application for two decades by now, and people still install cheap, unshielded cables. Just that unlike the early days, they nolonger carry "harmless" 6KHz wide AF signals, but extremely broad RF signals that pollute the radio spectrum up to 30MHz..
Any ideas why this hasn't changed?
Thanks in advance,
Edit: I'm aware that old telephone systems strictly speaking had no "ground" connection.
But DSL and ISDN are not like this anymore, I assume.
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