ADSL, being essentially a form of alternating current, will pass through an air gap. I was enlightened on this by an AT&T tech who pointed out that one of my ADSL lines had several breaks and could not carry DC but the ADSL signal still came through. The other line was dead so I was running essentially on one wire with an earth ground. Here is an interesting discussion:<p>"Phone line with 1 broken wire still gets ADSL2"<p><a href="https://forums.whirlpool.net.au/archive/9yzp5wr3" rel="nofollow">https://forums.whirlpool.net.au/archive/9yzp5wr3</a><p>Anyway, my hat is off to the people who designed and implemented ADSL.
That fact that this delivers 3.5 MBit/s really makes you wonder how many low speed connections out in the wild are literally broken cables that still have some amount of coupling somewhere.
I remember in the 90s when we were deploying a business campus, we first used ADSL services from the local carrier, but not for long.<p>We discovered we can get "dry lines", basically just rent copper run from site-to-site, nothing on it from local carrier. Slap ADSL modems on each and we got max throughout, at a fraction of the cost. Then we upgraded to SDSL, and that was like hitting the jackpot.
I’ll go one better, ADSL doesn’t even need two continuous wires to work, one is good enough as long as the other is just barely electrically coupled. I had a 12 month epic journey to get a performance fault fixed on my line. In the end it took 6 technician visits, three senior technicians and finally one smart experienced technician to check the “not in the textbook” faults for a performance degradation and he discovered that my line had was actually mis-wired! I had one wire connected to the exchange and another was a barely connected lose joint (actually disconnected but still technically in the plastic joint housing) about half way to the exchange. I was still getting a few megabits with intermittent drop outs for months on what amounted to a single wire!
Can ADSL survive an acoustic coupler?<p>To give it a fair shot, assume the driver and microphone are studio quality rather than the kind you’d find on a 1970s telephone handset. I bet it’d work pretty well.<p>But the real question would then be: how much of an air gap could you create and still get a connection?<p>Could you post to HN on an ADSL signal that’s being screamed across the length of the room you’re sitting in?
Most HDMI and Coaxial cables are little more than wet string<p><a href="https://ec.europa.eu/docsroom/documents/46433" rel="nofollow">https://ec.europa.eu/docsroom/documents/46433</a><p>>only 10% of the HDMI RMCD met an acceptable EMC quality of at least 50 dB coupling attenuation
Discussed at the time:<p><i>ADSL over wet string</i> - <a href="https://news.ycombinator.com/item?id=15908107" rel="nofollow">https://news.ycombinator.com/item?id=15908107</a> - Dec 2017 (88 comments)
There used to be a debate about going All-in on GPON or doing FTTX with G.Fast. Now G.Fast is pretty much dead or niche at this point. The end of DSL era. While DOCSIS is still doing well in many places.<p>The next step would be to mandate fibre cables in all new housing. Along with ONT and Router in one solution.
Since seeing this article I've been curious about organic conductors .. apparently most carbohydrates / celluloses are really not good basis for conduction but maybe there are tricks to change that.<p>- <a href="https://www.quora.com/Is-cellulose-fibre-conductive?share=1" rel="nofollow">https://www.quora.com/Is-cellulose-fibre-conductive?share=1</a><p>- <a href="https://duckduckgo.com/?t=ffab&q=conducting+polymers+examples&ia=web" rel="nofollow">https://duckduckgo.com/?t=ffab&q=conducting+polymers+example...</a>
If you want to try this at home, keep in mind that powerline is essentially the same thing - you don't necessarily need some DSLAM. Also these things spew so much RF they can frequently pair through thin air, just from radiated emissions.
It works on chickenwire too, VDSL not so much. Back in the day when i installed internet lines customers with mandatory ISP service requirement by the gov with absolute shit outside or inside wiring got ADSL, forward-error-correction magic. VDSL was a lot more sensitive.<p>In some cases I would be forced to use a cat-5 or even poor quality cat-3 where two pairs are for ethernet , one pair for A/VDSL and the blue pair for voice/POTS (voip to pots converted)
I think this relies on the particular string being a linear time-invariant channel. There is some limit where the string won't react accordingly (at a certain low or high frequency). What is that later phenomenon called, anyone know?
Honestly, any ODFM system is so incredibly resilient they will work over nearly any medium. I've tested powerline ethernet airgapped, and it still faster than the WiFI on the embedded system I was testing.