
ADSL over wet string - tomkap
http://www.revk.uk/2017/12/its-official-adsl-works-over-wet-string.html
======
eropple
I linked this to my dad (who's been a network engineer and CIO-type for nearly
thirty years) and his response kind of floored me: "yeah, we did this with
ARCNET. Brine-soaked twine." So, one, this is Older Than It Looks, and two,
apparently my dad might be a wizard?

~~~
bwann
I've often wondered if Ethernet can be ran over brine or wet string, if even
only just a few inches. I played with the idea once unsuccessfully but never
put more than five minutes into it.

~~~
simcop2387
I wouldn't expect modern 100BaseT or such to work, but probably the older
10Base2 over coax type ethernet i'd expect to work.

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lb1lf
Years ago, I tried the same thing on ham radio - made an antenna from a piece
of wet string and tried to call cq.

It worked a charm, though I had to continously wetten the string as I applied
RF power to it.

(21MHz ground plane antenna; eased the top end of the string through a hole
pierced in an empty beer can, suspended it from a tree and filled the can with
salt water.

Losses were huge, so antenna was easy to tune. Not the best of radiators,
though, but I did work twelve or thirteen countries with it.

Cost of string and beer - $4.

"Antenna this end is the proverbial piece of wet string - literally. Back to
you." -Priceless.

~~~
TeMPOraL
Just got my HAM license and callsign. Gonna try this out.

~~~
lb1lf
Just make sure not to use too much power - ten watts is plenty to start with.

Oh, and congratulations. You're in for a treat. (Though I would suggest not
using wet string as your only antenna. :-))

73 de LB1LF /OddE

~~~
jacquesm
You _really_ do not want to use too much power because when that string dries
up you'll end up frying your end stage if the stars don't align.

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AdmiralAsshat
Introducing: Verizon's post-net-neutrality definition of Broadband-ready
"fiber" lines.

~~~
discreditable
New plan to replace aging copper networks.

~~~
zingermc
Upgrade your business infrastructure to SaltyTwine™ today!

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scrollaway
For context, this is Adrian Kennard's blog. He's the CEO of AAISP (which I'd
highly recommend for UK residents, they're extremely ethical and transparent;
although I would not recommend their mobile service for different reasons).

~~~
jstanley
I recently switched to AA from Virgin Media due to the unreliability of
Virgin's service, but have found AA's to be no improvement.

I currently subscribe to both services and toggle back and forth whenever one
of them stops working.

I recommend AA for their philosophy, and the debugging tools in their web
interface are second to none, but in my brief experience the quality of their
actual service is no better than anyone else's.

~~~
scrollaway
> _in my brief experience the quality of their actual service is no better
> than anyone else 's._

It'll be better simply because they're better at _finding_ issues and
following up on them, but like most ISPs in the UK, they do not have their own
infrastructure.

There are three networks in the UK: British Telecom (BT, copper), TalkTalk
(TT, copper) and Virgin Media (cable). Virgin Media, in my experience, is the
most reliable network but unlike BT it is not available everywhere. AAISP use
both the BT and TT networks, and will offer you what is available, or let you
choose.

But if there are issues with BT/TT, you're outta luck. You can get, if you
like, two lines and have a failover or whatever, AAISP will in my experience
support you way, way more than any other ISP.

~~~
MrAlex94
> There are three networks in the UK:

It’s getting better though. Various smaller towns have access to Gigabit
internet at home now, but it’s still a tiny percentage of the population
(around 1.67%). [https://www.ispreview.co.uk/index.php/2017/09/ultrafast-
fibr...](https://www.ispreview.co.uk/index.php/2017/09/ultrafast-fibre-optic-
fttp-broadband-networks-cover-1-1-million-uk-premises.html)

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Negitivefrags
I once had an issue where my phone line was completely dead, but I was still
getting ADSL, just at very slow speeds. In the order of 1mbit.

After the technician came he told me that one of the two phone line wires had
been broken off at the exchange.

In other words, there wasn't a complete electrical circuit.

The phone was dead but ADSL still works without even having a complete
circuit.

I don't even understand how that can work at all.

~~~
Angostura
Did the dog bark just before an e-mail came in?

~~~
chipperyman573
What story is that? Google didn't return anything.

~~~
razakel
>What story is that? Google didn't return anything.

I'm not able to find a definitive source, but it could be the following, which
I have also heard from a retired BT employee:

"It's common practice in England to ring a telephone by sending extra voltage
across one side of the two wire circuit and ground (earth in England). When
the subscriber answers the phone, it switches to the two wire circuit for the
conversation. This method allows two parties on the same line to be signaled
without disturbing each other.

Anyway, an elderly lady with several pets called to say that her telephone
failed to ring when her friends called; and that on the few occasions when it
did ring her dog always barked first. The telephone repairman proceeded to the
scene, curious to see this psychic dog.

He climbed a nearby telephone pole, hooked in his test set, and dialed the
subscriber's house. The phone didn't ring. He tried again. The dog barked
loudly, followed by a ringing telephone.

Climbing down from the pole, the telephone repairman found:

a. The dog was tied to the telephone system's ground post via an iron chain
and collar.

b. The dog was receiving 90 volts of signaling current.

c. After several such jolts, the dog would start barking and urinating on the
ground.

d. The wet ground now completed the circuit and the phone would ring."

~~~
jacquesm
I'll bet it was a German dog. German dogs 'bell'.

[https://www.linguee.de/deutsch-
englisch/uebersetzung/der+hun...](https://www.linguee.de/deutsch-
englisch/uebersetzung/der+hund+bellt.html)

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circlingthesun
"As a bonus, fit tin cans to both ends and you get voice as well as broadband
on the same wet string!"

Ha!

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ClassyJacket
I'm sure Australia's NBN will add this to their 'multi technology' mix any day
now.

~~~
King-Aaron
Every time it rains, my local copper pit fills with water and my internet
drops out.

Maybe they should replace the copper with Damp Twine to the Node.

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UseStrict
Take a net, dip it in water, boom! Mesh networking.

~~~
wyldfire
You're joking, but that was the first application I thought of.

It would be really interesting to create a low-throughput fallback network for
neighborhoods using something like this. Though I suppose RF or optical are
still quite a bit more practical.

~~~
topranks
Or copper.

You'll never justify your choice of "wet string" as medium of choice when
things go south.

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toomanybeersies
Hot dogs are also conductive, since they are also filled with salt water. I
wonder if you could do ADSL-over-hotdog. Obviously the length would be limited
by the length of a frankfurter, so you wouldn't be able to get more than a
foot or so, but it would be an interesting experiment.

A pickle might work too.

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korethr
So, now that the concept has been proven, are we going to see a proper RFC
proposal to standardize this? There's still 110 days left for submissions.
That should be plenty of time to test what string types and electrolytes work
best for various applications, to and improve the distance limit.

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runeks
After another 10 ADSL iterations, I think someone will accidentally forget to
connect the wires and discover that it works just fine over the air.

~~~
jwfxpr
Broadband without wires? Preposterous.

~~~
jschwartzi
Yeah, how would we charge money for it?

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moultano
Anyone have a link that explains (ideally with some math) how this works?

~~~
topspin
The pair of parallel conductors (wet string) forms a balanced transmission
line[1] just like the copper pair in traditional phone line. The ADSL
transceivers at each end automatically adapt to the available transmission
line; you'll note that instrument reports that this 2 meter line looks like
4.5km of copper; it is a very poor conductor, so the ADSL transceivers fall
back to lower frequency operation, which is apparently sufficient for low
speed communication.

I do wonder about impedance matching here. Traditional phone lines apparently
have a characteristic impedance of either 600 or 900 ohms. That pair of wet
strings look to be separated by about the right distance to produce impedance
in that neighborhood, or maybe the line length is tuned to eliminate
reactance. It isn't mentioned but I suspect that RevK understood this.

[1]
[https://en.wikipedia.org/wiki/Transmission_line](https://en.wikipedia.org/wiki/Transmission_line)

~~~
0x47df
Whilst the impedance of the line under yesterday's test conditions wasn't
measured, it was replicated again this morning, and from memory it was around
the 900 ohm mark. I'll be testing again tomorrow (trying to run bonded data
across two of them) so I'll try and get a recorded measurement of the line's
impedance at some point rather than just something from memory.

~~~
topspin
Great! That will be very interesting. It was just guesstimation on my part but
the diameter and separation of the strings looked similar to high impedance
lines used in SW amateur equipment typically in the 400-600 ohm range. A
couple sites I've read state that ASDL actually experiences about 100 ohms
impedance as opposed to voice (600 ohms) due to the large frequency
difference. If all that is true then bringing the strings closer together will
lower impedance which should improve the match.

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Humphrey
Perhaps some Australian NBN (National Broadband Network) customers would get
improved speeds with wet string over their fibre to the node installations

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grandalf
I wish more science were taught using this kind of thing as a starting demo to
provoke a lot of wonderment.

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lerie82
"salty wet twisted pair", lovely.

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gonzo
I once did this with HPNA 1.0

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nathancahill
Not sure if science or another pro net neutrality piece.

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macawfish
_" He got some proper string, and made it wet..."_

~~~
macawfish
idk what people thought i was alluding to here, i just thought it was a
fun/funny way to talk about the experimental setup. get your minds out of the
gutter!

