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ADSL works over wet string (2017)

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Re: ADSL works over wet string (2017)

#61

Post by samwillis »

DaiPlusPlus wrote: post #45
giardini wrote: post #23

ADSL, being essentially a form of alternating current, will pass through an air gap. I was enlightened on this by an AT&T tech who pointed out that one of my ADSL lines had several breaks and could not carry DC but the ADSL signal still came through. The other line was dead so I was running essentially on one wire with an earth ground. Here is an interesting discussion: "Phone line with 1 broken wire still gets ADSL2…

> Anyway, my hat is off to the people who designed and implemented ADSL. It's a blessing-and-a-curse: too many incumbent ISPs in highly-developed nations used ADSL's ability to run on anything as an excuse to put-off FTTH deployments (looking at you, BT).

I think we (in Stamford Lincolnshire, UK) must be pretty unique right now with TWO competing FTTP startups both rolling out on the same streets. One day you will see Lightspeed Broadband pulling their fibre through the BT ducts and putting boxes on the top of telegraph polls. The next day Upp Brordband will be on the same street. So bizarre they they are doing the same town!

Apparently we are due to have BT put in their own fibre in the next few months too. Really don’t understand why they are doubling up the infrastructure.

Hoping for a local price war!

Re: ADSL works over wet string (2017)

#62

Post by hammock »

sdflhasjd wrote: post #14
agumonkey wrote: post #3

Since seeing this article I've been curious about organic conductors .. apparently most carbohydrates / celluloses are really not good basis for conduction but maybe there are tricks to change that. - https://www.quora.com/Is-cellulose-fibre-conductive?share=1 - https://duckduckgo.com/?t=ffab&q=conducting+polymers+example...

Paper and cotton were both used in cable insulation in ye olden days, impregnated with oils and tars

What do they use now?

Re: ADSL works over wet string (2017)

#63

Post by tiernano »

giardini wrote: post #23

ADSL, being essentially a form of alternating current, will pass through an air gap. I was enlightened on this by an AT&T tech who pointed out that one of my ADSL lines had several breaks and could not carry DC but the ADSL signal still came through. The other line was dead so I was running essentially on one wire with an earth ground. Here is an interesting discussion: "Phone line with 1 broken wire still gets ADSL2…

this explains a problem i had in Ireland... ADSL worked, but phone line had to dial tone... engineer had no idea how it was working... mind you, ISP had sent him out to get better internet... i was on 8mb and was promised closer to 24... after he "fixed" it, it went to 6... so they were really not happy with the "engineer" when i canceled 2 days later...

Re: ADSL works over wet string (2017)

#64

Post by [deleted] »

giardini wrote: post #23

ADSL, being essentially a form of alternating current, will pass through an air gap. I was enlightened on this by an AT&T tech who pointed out that one of my ADSL lines had several breaks and could not carry DC but the ADSL signal still came through. The other line was dead so I was running essentially on one wire with an earth ground. Here is an interesting discussion: "Phone line with 1 broken wire still gets ADSL2…

[deleted]

Re: ADSL works over wet string (2017)

#65

Post by andoma »

giardini wrote: post #23

ADSL, being essentially a form of alternating current, will pass through an air gap. I was enlightened on this by an AT&T tech who pointed out that one of my ADSL lines had several breaks and could not carry DC but the ADSL signal still came through. The other line was dead so I was running essentially on one wire with an earth ground. Here is an interesting discussion: "Phone line with 1 broken wire still gets ADSL2…

Same thing happened once at my parents house. Quite confusing for some :)

Re: ADSL works over wet string (2017)

#66

Post by aphrax »

samwillis wrote: post #61
DaiPlusPlus wrote: post #45

Earlier quoted context omitted.

> Anyway, my hat is off to the people who designed and implemented ADSL. It's a blessing-and-a-curse: too many incumbent ISPs in highly-developed nations used ADSL's ability to run on anything as an excuse to put-off FTTH deployments (looking at you, BT).

I think we (in Stamford Lincolnshire, UK) must be pretty unique right now with TWO competing FTTP startups both rolling out on the same streets. One day you will see Lightspeed Broadband pulling their fibre through the BT ducts and putting boxes on the top of telegraph polls. The next day Upp Brordband will be on the same street. So bizarre they they are doing the same town! Apparently we are due to have BT put in th…

How strange to see my hometown mentioned! Still not too far away and yes hoping for some local competition

Re: ADSL works over wet string (2017)

#67

Post by y04nn »

geofft wrote: post #43
giardini wrote: post #23

ADSL, being essentially a form of alternating current, will pass through an air gap. I was enlightened on this by an AT&T tech who pointed out that one of my ADSL lines had several breaks and could not carry DC but the ADSL signal still came through. The other line was dead so I was running essentially on one wire with an earth ground. Here is an interesting discussion: "Phone line with 1 broken wire still gets ADSL2…

In some sense, that's "just" radio. An antenna is a wire... it's sending a signal and picking it up from a very nearby antenna. Radio transmissions are all AC. (Arguably, the real insight here is that the very existence of radio is impressive / unintuitive.)

The gap on the line acts more as a capacitor than an antenna, AC pass through capacitors, but DC does not.

Re: ADSL works over wet string (2017)

#68

Post by stefan_ »

If you want to try this at home, keep in mind that powerline is essentially the same thing - you don't necessarily need some DSLAM. Also these things spew so much RF they can frequently pair through thin air, just from radiated emissions.

Re: ADSL works over wet string (2017)

#69

Post by throw0101a »

Faaak wrote: post #11

Related: ethernet over barbed wire: http://www.sigcon.com/Pubs/edn/SoGoodBarbedWire.htm

There are IEEE standards for single-pair Ethernet:

> In addition to the more computer-oriented two and four-pair variants, the 10BASE-T1,[17] 100BASE-T1[18] and 1000BASE-T1[19] single-pair Ethernet physical layers are intended for industrial and automotive applications[20] or as optional data channels in other interconnect applications.[21] The single pair operates at full duplex and has a maximum reach of 15 m or 49 ft (100BASE-T1, 1000BASE-T1 link segment type A) or up to 40 m or 130 ft (1000BASE-T1 link segment type B) with up to four in-line connectors. Both physical layers require a balanced twisted pair with an impedance of 100 Ω. The cable must be capable of transmitting 600 MHz for 1000BASE-T1 and 66 MHz for 100BASE-T1. 2.5 Gb/s, 5 Gb/s, and 10 Gb/s over a 15 m single pair is standardized in 802.3ch-2020.[22] As of 2021, the P802.3cy Task Force is examining having 25, 50, 100 Gb/s speeds at lengths up to 11 m.[23]

* https://en.wikipedia.org/wiki/Ethernet_over_twisted_pair#Sin...

Including power delivery:

> The IEEE 802.3bu-2016[12] amendment introduced single-pair Power over Data Lines (PoDL) for the single-pair Ethernet standards 100BASE-T1 and 1000BASE-T1 intended for automotive and industrial applications.[13] On the two-pair or four-pair standards, power is transmitted only between pairs, so that within each pair there is no voltage present other than that representing the transmitted data. With single-pair Ethernet, power is transmitted in parallel to the data. PoDL initially defined ten power classes, ranging from 0.5 to 50 W (at PD).

> Subsequently, PoDL was added to the single-pair variants 10BASE-T1,[14] 2.5GBASE-T1, 5GBASE-T1, and 10GBASE-T1[15] and as of 2021 includes a total of 15 power classes with additional intermediate voltage and power levels.[14]

* https://en.wikipedia.org/wiki/Power_over_Ethernet#PoDL

Re: ADSL works over wet string (2017)

#70

Post by rootusrootus »

kabdib wrote: post #52
someperson wrote: post #8

Earlier quoted context omitted.

Potentially apocryphal, but Telstra's copper cable network supposedly had its insulation made of paper, not rubber. I remember when it rained the curbside pits fill with water, causing slowdowns and frequent ADSL dropouts (until things dried out).

It took over a year for Ziply to repair the land line of my 90-year-old parents. 30+ hours on the phone with support, multiple visits by techs who were simply not interested in doing any work. I had a tech tell me, literally to my face, "this line is working fine" when the line was stone dead. Another told me that I had to buy all new phones because the ones my parents had were "out of date". (To humor him, I bought…

> I have now learned that the WA state utilities commission is pretty interested when providers try to pull stunts like this.

A number of years ago I worked at a CLEC, during that short window of time when they could exist. One of the more useful things I learned is how much power the PUC has. Every phone company has a team that deals with complaints coming in via the PUC and they are eager to resolve them. Not something I'd necessarily use in lieu of regular old customer service for most issues, but when the first and second attempts fail, calling the PUC will work 100% of the time.

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