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10mbps over 1km on a single pair of wires

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

#101

Post by kombre »

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…

>oh, fiber materials may be sand

what does sand means in this context please ?

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

#102

Post by willglynn »

aidenn0 wrote: post #91
cm2187 wrote: post #87

Earlier quoted context omitted.

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.

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 the pair on the secondary side, no problem. If a wire pair suddenly measures a thousand volts across… well, Ethernet transformers are typically wound 1:1.

_Ideal_ magnetic coupling removes issues with potentials. Ideal transformers behave as above, but real transformers have parasitic effects, particularly winding capacitance. Fast transients (including ESD) can and do capacitively couple across the transformer from primary to secondary.

Magnetics are important but do not solve the problem on their own. It is possible to design and manufacture electrically robust copper Ethernet systems – for a given definition of robustness (typically defined as passing some specific EMC test) – but even then real world electrical faults can and do destroy robust Ethernet systems. Fiber has none of these concerns.

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

#103

Post by p1mrx »

DannyBee wrote: post #48
silviot wrote: post #21

Earlier quoted context omitted.

What's the difference in price between 1km of fiber vs 1km or single pair wire? It might play a role in this solution being cheaper than immediately apparent.

The fiber is much cheaper because it's so much more common. For example: I/O fiber is about 0.10 cents a foot or less for 2 fiber cable. (12 fiber is only 20 cents a foot). OSP gel-filled direct burial is 0.55 cents a foot or less for 2 fiber cable. (12 fiber is only 65 cents). This is micro-armored OSP cable, resistant to chewing/damage as well. Basic 18 awg single pair shielded direct burial wire is about 0.80 cent…

> 0.80 cents a foot

Isn't that 80 cents/foot, or 0.80 dollars/foot?

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

#104

Post by hervature »

kombre wrote: post #101
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…

>oh, fiber materials may be sand what does sand means in this context please ?

Fiber optics cables are made of glass whose primary constituent is silicon dioxide and/or quartz which are the primary constituents of sand.

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

#106

Post by [deleted] »

varjag wrote: post #26
worldofmatthew wrote: post #22

Something like this is what this is competing with; https://www.ebay.co.uk/itm/314029740243 In the US, you will be able to get these cheaper than the product on Botblox and with better performance (both products require a pair). "20/12Mbps over a long distance of 1.4km" The author might be more competitive when he managers to go $100/pair (which he mentioned in another post he plans to by Apr 2023).

DSL isn't it. Not anywhere as easy to embed into products as 2 wire Ethernet, and you miss PoE option.

[deleted]

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

#107

Post by kombre »

hervature wrote: post #104
kombre wrote: post #101

Earlier quoted context omitted.

>oh, fiber materials may be sand what does sand means in this context please ?

Fiber optics cables are made of glass whose primary constituent is silicon dioxide and/or quartz which are the primary constituents of sand.

oh okay, thx

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

#108

Post by kube-system »

yetihehe wrote: post #7
yosheli123 wrote: post #2

So I built a tiny single pair Ethernet bridge (10BASE-T1L) that can transmit 10mbps over a kilometer on a single pair of twisted copper wires. Would love to get some feedback for the next iteration

> 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

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

#109

Post by baldfat »

netsharc wrote: post #88
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…

Al Gore never claimed that, btw, but he did recognize its importance and provided political support, even Vint Cerf said so: https://www.snopes.com/fact-check/internet-of-lies/

No post body was provided.

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

#110

Post by tomhoward »

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 premises to ours. I guess they just patched them together at the exchange? It was a pretty small catchment area. Fun times!
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