
Ethernet over barbed wire - provost
http://www.sigcon.com/Pubs/edn/SoGoodBarbedWire.htm
======
slinkyavenger
It's a nice callback to early phone infrastructure, which leveraged barbed-
wire fences to bring service to those who lived in rural areas:
[https://en.wikipedia.org/wiki/Barbed_wire_telephone_lines](https://en.wikipedia.org/wiki/Barbed_wire_telephone_lines)

~~~
cellularmitosis
I wonder if this is one of the reasons why the phone system standardized on 48
volts. With DC, you need to get above about 60 volts to have any chance of
lethality. If someone were to grab the barbed wire, they'd get a jolt, but it
wouldn't kill them.

~~~
amigoingtodie
I believe current is a more prevelant factor in electrocution.

[edit] Found this:
[https://en.wikipedia.org/wiki/Tip_and_ring#Line_voltage](https://en.wikipedia.org/wiki/Tip_and_ring#Line_voltage)

~~~
moron4hire
Yes, it is _technically_ true that it is the current that disrupts the heart
rhythm. Theoretically, a 9v battery can supply enough current to cause a
potentially fatal heart arrhythmia, if it's shorted through a person's blood.
But it's also being pedantic.

Consider Ohm's Law: `I = V/R`. Why is it so frequently printed in this way,
rather than the simpler `IR = V`? If we don't care about simplicity, why not
`V = I/R`? What is special about `I = V/R`?

Resistance--be it your work load or your human fleshy bits--is usually roughly
considered a constant--or at least a known--for a given application. And most
power sources that you'll encounter in the wild are voltage-controlled and
able to supply practically as much current as you want (aka "more than enough
to kill you"). So Voltage is the independent variable, leaving Current to be
the dependent variable.

While it is true that "it's the current that gets ya", it's the voltage over
which we have control, so we tend to focus on that instead.

~~~
leggomylibro
I always learned Ohm's law as, "V = I*R". You know, over the handful of
classes that included it at some point. When you say 'Ohm's law,' my brain
says 'vee-equals-aye-arr.' So...I did check wikipedia first to make sure I
wasn't having a stroke, but I think 'V=I/R' is a typo.

Anyways, that does seem fairly self-explanatory. More volts means more current
with the same resistance. More resistance means less current with the same
voltage.

------
j_s
source:
[https://news.ycombinator.com/item?id=15909261](https://news.ycombinator.com/item?id=15909261)

on (somewhat?) related front page discussion:
[https://news.ycombinator.com/item?id=15908107](https://news.ycombinator.com/item?id=15908107)
(ADSL over wet string)

also linked there: [https://www.atlasobscura.com/articles/barbed-wire-
telephone-...](https://www.atlasobscura.com/articles/barbed-wire-telephone-
lines-homesteaders-prairie-america-history)

------
sonium
People might find it intersting to know that in the car industry Gigabit
Ethernet over unshielded twisted pair is common [1] since it allows to shave
off some cents on extra copper.

[1]
[http://www.marvell.com/company/news/pressDetail.do?releaseID...](http://www.marvell.com/company/news/pressDetail.do?releaseID=7256)

~~~
bsder
Has this become standardized yet? I've got a bunch of multi-drop CAN stuff
that I would _LOVE_ to move over to single pair ethernet with multi-drop a la
10BASE2. Unfortunately I haven't see a 10BASE2 compatible PHY in 20+ years.

IEEE had a working group on this but I hadn't seen any actually shipping chips
that mortals could get their hands on.

(Edit: Apparently still vapor. Still can't find a source for the Marvell
88Q1010 & 88Q2112.)

(Edit: Only thing available seems to be this which is almost certainly some
gigantic FPGA solution ... [https://beyondstandards.ieee.org/connected-
vehicles/intrepid...](https://beyondstandards.ieee.org/connected-
vehicles/intrepid-rad-supermoon-first-1000base-t1-media-converter-avbtsn-
support/))

~~~
voxadam
What are your bandwidth and latency requirement? More than once I've pondered
6LoWPAN over RS485 using token passing.

~~~
bsder
My biggest problem is _software stack_ performance--not physical layer
performance. Most protocol stacks in the embedded space other than TCP/IP are
mind-blowingly bad.

Being able to obliterate USB, CAN, and RS-232 (to a lesser degree--RS-232 is
really reliable but the problem is generally in frequency drift if you don't
have a crystal anywhere) in all of my designs and replacing it with ethernet
will dramatically improve the reliability of my hardware. The only places I
don't currently have ethernet in my designs are where I'm limited to a single
pair of wires.

As for RS485, it doesn't really offer me anything that I don't already get
with CAN.

~~~
IgorPartola
What do you work on?

~~~
bsder
Lots of industrial stuff related to various types of testing. Performance
matters some, but I'm not hard real-time.

However, everything has to work, _reliably_ , in less than ideal environments
--mostly high-voltage spikes caused by differences in ground potentials.

USB is a PITA because while data is differential, _connection detection_ is
not. So, spikes cause USB disconnects and drivers never cope with that.

CAN is a PITA because it is limited to 8-bytes per message. Good for
transducers and 8 bit microcontrollers--not so good for complex control and
32-bit microcontrollers.

Ethernet hits a really great sweet spot of fully-differential and nice single
packet size for a 32-bit microcontroller--program like it's 1989, baby.

~~~
voxadam
I absolutely agree that Ethernet is ideal and the correct solution for modern
systems. Have you worked with EtherCAT at all?

------
himom
It would be neat to have a mesh topology that uses the bandwidth and
redundancy of multiple fence paths in order to prevent an outage from damage
to any one particular fence. Solar-powered routers anyone?

Otherwise: _Dabnabbit Maude, the cows gone loose again because we lost the
interwebs._ (I’m half-Texan so it’s not -ist.)

~~~
Bartweiss
Bizarrely, that's close to a real problem! Ethernet over barbed wire may have
been just for show, but phone service over it was a very real approach.

Perhaps not "the internet released the cows", but at least "the stampede cut
the phone lines".

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

------
dogma1138
Too bad there are sanctions against North Korea, it seems like this would be a
perfect fit for Kwangmyong[1].

[1][https://en.wikipedia.org/wiki/Kwangmyong_(network)](https://en.wikipedia.org/wiki/Kwangmyong_\(network\))

~~~
ryacko
Patent law doesn't work against a sovereign state.

So yes, they probably violate the GPL.

------
mschuster91
Can I run this on a farm?

Seriously, this reminds me about the stories I read on HN about how early
telephone networks were established by farmers (ab)using their electric
fencing for communication.

~~~
digi_owl
No surprise there, as analog phones are basically two lines of telegraph wire.

------
randomerr
Are there modules I can experiment with?

Related link:
[https://books.google.com/books?id=mMJxcWqm_1oC&pg=PA34&lpg=P...](https://books.google.com/books?id=mMJxcWqm_1oC&pg=PA34&lpg=PA34&dq=Broadcom%27s+T4&source=bl&ots=73okOWEqdp&sig=1iIW9NPoRbzneLPEiq8X0NyVk44&hl=en&sa=X&ved=0ahUKEwig1qmA9YbYAhXH1CYKHZB7C1YQ6AEIMDAB#v=onepage&q=Broadcom's%20T4&f=false)

~~~
pjc50
I'm not sure what you mean, you can just splice your barbed wire into Ethernet
cable and plug it into regular transcievers that you already have.

------
omg_ketchup
Who needs https when you have barbed wire?

~~~
StavrosK
Everyone? It's trivial to tap barbed wire.

------
matthberg
Needs a (2001) tag, but fascinating demonstration with get marketing.

------
throwaway413
Talk about a secure connection.

------
frik
> In 1998, Wide-Band Systems demonstrates Gigabit Ethernet running on four
> pairs of old, rusty barbed wire.

Yet in 2017 we still have only 1Gbit Ethernet in LANs :(

1Gbps = 125 MB/s !!

I am running 1Gbit since 2003 at home. And all f..king home network devices
still support only 1Gbit Ethernet. It's not fast enough. When can some network
company finally release 10Gbit or 100Gbit Ethernet (copper or fiber) for cheap
home usage.

~~~
krylon
I feel for you, but I think if you need a 10GBit or 100GBit network at home,
your needs are a little extreme.

My home network still runs on 100MBit, because of a stubborn old switch that
refuses to die. By now, my curiosity to see how long this thing will last (it
is about 13.5 years old) outweighs my impatience when pushing large files
around. ;-)

~~~
stordoff
Definitely on the high end, but having centralised most of my storage
(backups, media etc.) to a NAS, 10Gbps would definitely be welcome. Pushing
large backups to my NAS is time-consuming, and e.g. video editing basically
requires pulling it down to a local drive first (not to say it'd be ideal to
use a network store for that at all, but it'd be more viable).

