10mbps over 1km on a single pair of wires • Hacker News Board

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

#221

Post by mrjin » Thu, Jun 23, 2022, 8:21 AM UTC

BenjiWiebe wrote: post #208

mrjin wrote: post #41

Earlier quoted context omitted.

Further more, why would someone choose this over $59.69 a pair fiber ether net media converter, up to 20KM, 1000Mbps from TP-LINK? There are most likely cheaper options from other vendors. https://www.aliexpress.com/item/1005001435649462.html

Don't forget the SFP's you need as well.

There are actually different models have laser trans-receivers built in with same or might even cheaper price. So unless there are very special requirements, I don't really see a reason to go for those.

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

#222

Post by mmac_ » Thu, Jun 23, 2022, 12:16 PM UTC

Single pair communications are invaluable in industrial applications - almost all of our scenarios involve the restriction of not being able to run new cable. The costs involved in running new cables can be eye watering to say the least. If you're on a greenfield project, then there are surely better solutions since you have the luxury of designing the cable runs.

VDSL has been king in the areas I work in for quite a few years now and has been very reliable. We are experimenting with SPE and it's looking positive with the biggest benefit being cost. SPE for us is a significant cost down that will allow us to design it into more products where VDSL blew the BOM budget. We'll still use VDSL when we need higher bandwidth but only have that single copper pair.

SPE fills a gap where you need a decent amount of bandwidth at a reasonable distance for a low price. For us it complements modbus, standard ethernet, vdsl etc.

SPE is also very new with the chipsets really only starting to become available in the last 12 months or so. Chip shortages aren't helping but expect to start seeing these solutions pop up all over the place.

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

#223

Post by DannyBee » Thu, Jun 23, 2022, 6:08 PM UTC

toast0 wrote: post #219

DannyBee wrote: post #179

Earlier quoted context omitted.

in which case unless you have 18awg copper lines around, you can't do 1km :) I would be shocked if anyone has those. Maybe alarm wire I guess?

I've got a 3 pair run[1] to my gate with a keypad gate controller. Two pair are used for voice communications, and one pair is idle. The gate controller has 10 base T ethernet (for management), but you need two pair, and it's maybe a touch outside the distance spec for 10baseT. I'm not quite ready to spend $350 to get it on ethernet though. [1] Actually, it's 4 pair to an in-ground junction box, where it splices to 3…

Unlike the 1km, this doesn't require 18awg wire :)

10Base-T1L may replace RS-485 in forms of process automation, but the length capability is not the particularly interesting feature there :)

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

#224

Post by xenadu02 » Fri, Jun 24, 2022, 7:27 PM UTC

Aloha wrote: post #188

xenadu02 wrote: post #181

Earlier quoted context omitted.

This sounds like post-hoc rationalization. I have Sonic fiber in SF. 1Gbps symmetric, over a "fragile fiber" run directly into my home. It works quite well. The drop cable is pre-made in standard lengths with weatherproof connectors. The glass is embedded in a large-ish diameter substrate that resists sharp bends naturally so the installers don't need to take special care to prevent losses, just don't try to force th…

Does Sonic own their own fiber network?

Sorry I should have been clearer: I am referring to "Sonic Fiber" which is their own infrastructure, not any kind of resold service which they do offer in areas where they have not deployed their own fiber infrastructure.

In the Bay Area they have fiber in SF, South SF, Daly City, Redwood City, Berkley, Oakland, San Carlos, Burlingame, Albany, Brentwood, and probably more. They are rolling it out mostly in areas with poles at the moment because the cost of burying is quite high.

They've proposed "microtrenching" in SF to reach areas with all underground utilities but so far the city hasn't been very interested and it isn't cost-effective for them to dig up the sidewalks to install conduit. I hope that will change at some point.

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

#225

Post by watersb » Sat, Jun 25, 2022, 8:37 AM UTC

jcrawfordor wrote: post #209

watersb wrote: post #180

Earlier quoted context omitted.

I can't tell exactly from a quick scan of Cringeley's commentary... but I get the impression that a "dry copper pair" the single-pair POTS equivalent of "dark fiber"... with the critical caveat that a dry copper pair can link two points only if they are serviced by the same central telephone company switch.

A leased loop is any arrangement where a customer pays the telco for a dedicated loop for continuous use. A dry loop is a type of leased loop that isn't connected to any telco equipment, just spliced together to create a continuous circuit (a typical or 'wet' leased loop has at least battery and sometimes dial tone from the telephone switch). It's perfectly possible to get a leased line that spans telco offices, in w…

Thanks, that explains it quite nicely.

1990s AppleTalk networks could work over a single pair. I ran a network with hundreds of Macs for a tech company. Ten buildings in a small campus.

Still remember the day the fire-alarm techs punched down over one of the Macs in the executive office. Not much of a network signal when there's 24 Volts on the same line.