Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

10mbps over 1km on a single pair of wires

botblox.io

Post reply on HN
Print view View original

121–130 of 225 posts

Re: 10mbps over 1km on a single pair of wires

#121

Post by EvanAnderson »

tomhoward wrote: post #110
geozimm wrote: post #84

All these things are related. Back in the 1990s I worked with others to develop DSL technologies (ADSL, HDSL, VDSL) for telcos. Why not fiber, some ask? oh, fiber materials may be sand, but installed fiber is sand, energy, and labor. Installation costs trump everything - use what you have for the physical medium. While we (PairGain) also made point-to-point private links, it was clear then, and even moreso now that m…

Cool to see you here on HN. I hadn't heard the name PairGain since I worked for a small corporate ISP in the early 2000s. We'd recommend PairGain modems for clients who needed seriously high-speed links of 2Mbps! This was just before ADSL and SHDSL were rolled out en masse, or at least well before they were reliable enough for corporate use. We had to organise a special installation of a direct copper line from their…

The tariff in my locality allowed for dry copper pairs to be installed ("burglar alarm circuits") and some of my Customers took advantage of that along w/ PairGain devices to get high speed links between sites serviced out of the same central office.

Relevant article: http://helices.org/commentary/dry_copper_pair.html

Re: 10mbps over 1km on a single pair of wires

#122

Post by aidenn0 »

willglynn wrote: post #102
aidenn0 wrote: post #91

Earlier quoted context omitted.

Magnetic coupling removes any issues with potentials, and if it's not AC at the same frequency as what's in the wall, the phase is irrelevant.

I'd like to add a few asterisks: Magnetic coupling removes issues with potentials _up to the dielectric breakdown voltage_. Ethernet magnetics are considered high potential components, and even the entry level options will isolate at least 1.5kV, but fault events often exceed that figure. Magnetic coupling removes issues with _common mode_ potentials. If the + and - side of a pair are both a thousand volts away from…

All very true; good clarifications. In context my point was that it would be totally safe to run a copper Ethernet cable between two houses on separate electrical grids (or even an un-earthed battery powered computer).

Re: 10mbps over 1km on a single pair of wires

#123

Post by ladyattis »

I wonder if keeping the wires on a spool is what allows the speed to be the range of 10mbps? I only ask because I know at least for radio signals there's capacitive coupling between wires which some signal leakage will happen. But I assume as long as the signals are differential as in current flow between the two wires are in opposition which should in theory be fine, so common mode signals ought not to leak over.

Re: 10mbps over 1km on a single pair of wires

#126

Post by ComputerGuru »

aidos wrote: post #86
trollied wrote: post #40

A few years ago, revk (owner of an ISP in the UK) did ADSL over wet string: https://www.revk.uk/2017/12/its-official-adsl-works-over-wet...

The HN post at the time: https://news.ycombinator.com/item?id=29440681 RevK is the owner of AAISP (an xkcd/806 compliant organisation).

https://xkcd.com/806/

https://www.revk.uk/2010/10/xkcd806-compliance.html?m=1

Re: 10mbps over 1km on a single pair of wires

#127

Post by RedShift1 »

tiffanyh wrote: post #125

Most don't realize, you can run 400mbps of data over your old in-home electrical wiring. https://www.digitaltrends.com/computing/everything-you-need-...

My experience with powerline adapters is that they all fail sooner or later... I think 230 V is just too much to handle in a small package combined with sensitive low voltage communication chips.

Re: 10mbps over 1km on a single pair of wires

#128

Post by madengr »

hotpotamus wrote: post #52
madengr wrote: post #14

Earlier quoted context omitted.

I wired my house with 62/125 fiber 22 years ago as a 1 km spool was only $250. I’m too lazy to look it up, but I suspect multimode fiber is cheaper than copper, and termination kits are cheap now. I’m running 10G on single mode 100 ft jumpers to a few computers in the house and that’s cheap too. SFP are $35 but the NIC are more.

Yeah, multimode fiber seems to be the red headed step child of the networking world these days, but that's a good question about the cost of it vs copper. It's just plastic, right? It seems like a good option for high speed SOHO or perhaps within rack networking. But if I was running cable in my house today, I think I'd still go copper for PoE capability.

Yeah, POE is great. I have a 48 port Ubiquiti switch with POE AP and cameras. I ran duplex fiber and 2 pair of shielded CAT 5 to each room. For the downstairs rooms, those are through short runs of conduit to the basement, so I can poke whatever else through there, like the single mode jumpers. I should have run conduit upstairs, but I do have a 4" PVC running from basement to attic, so I could run single mode upstairs, but would require drilling and fishing.

Re: 10mbps over 1km on a single pair of wires

#129

Post by jeroenhd »

kube-system wrote: post #108
yetihehe wrote: post #7

Earlier quoted context omitted.

> Any application requiring a simple, low cost, robust connection between physically disparate devices At $195 it's definitely not low cost.

“Low cost” is relative. For parts in the industrial/robotics space, $195 is not expensive. You can certainly spend more on other options: https://westwardsales.com/patton-cl2300e-ethernet-extender

You can get full products that do higher speeds over longer distances at lower cost, search term "vdsl repeater".

It's possible that this product handles bad wiring better as it's ethernet rather than VDSL2, but I think those devices are a much better fit.

One thing that might be better with an ethernet based standard is the ability to add multiple stations to the same link, relying on ethernet's error correction.

Re: 10mbps over 1km on a single pair of wires

#130

Post by dekhn »

cm2187 wrote: post #87
geozimm wrote: post #84

All these things are related. Back in the 1990s I worked with others to develop DSL technologies (ADSL, HDSL, VDSL) for telcos. Why not fiber, some ask? oh, fiber materials may be sand, but installed fiber is sand, energy, and labor. Installation costs trump everything - use what you have for the physical medium. While we (PairGain) also made point-to-point private links, it was clear then, and even moreso now that m…

Fiber doesn’t conduct electricity, a wire does. I remember reading somewhere to be careful with running a wire over any long distance between two houses that are not connected to the grid with the same meter. Something to do with phase or different potential, can’t remember, but the point was it could fry your equipment. Fiber sounds a lot safer to me.

Any long run like this would use optoisolaters.
Post reply on HN