ADSL over wet string
revk.uk
revk.uk
Always with the recursion.
reminded about other sodium ion transmission channels - our nerves.
if you can rig the equipment to provide five voltages over four dimensions...
It worked a charm, though I had to continously wetten the string as I applied RF power to it.
(21MHz ground plane antenna; eased the top end of the string through a hole pierced in an empty beer can, suspended it from a tree and filled the can with salt water.
Losses were huge, so antenna was easy to tune. Not the best of radiators, though, but I did work twelve or thirteen countries with it.
Cost of string and beer - $4.
"Antenna this end is the proverbial piece of wet string - literally. Back to you." -Priceless.
Oh, and congratulations. You're in for a treat. (Though I would suggest not using wet string as your only antenna. :-))
73 de LB1LF /OddE
Probably harder now that we're in a solar minimum but you'd have decent luck on CW.
I currently subscribe to both services and toggle back and forth whenever one of them stops working.
I recommend AA for their philosophy, and the debugging tools in their web interface are second to none, but in my brief experience the quality of their actual service is no better than anyone else's.
They are still beholden to Openreach, but they will actively manage them vs. just take them at face value/accept what they are being told.
Another option for you in particular (if you're willing to keep paying for both virgin and AAISP) is to set up a router with multi-WAN support which can load balance between both wans and handle failures, instead of swapping manually.
So, an online game will disconnect and a video stream will stop. You will however be able to reconnect or refresh right away.
I had it for 2 odd years: you get a few dropped packets before the system realises a line has become unavailable
if it hadn't been for the email telling me I'd never have noticed that a line dropped: connections remained established and downloads continued (at a lower speed)
WAN County ---- WAN City ---- WAN Street ---- HOUSE
|--------- HOUSE
let me repeat: it is possible to get real failover from the same ISP. It will however be extremely costly, and just getting two lanes from the same Street Router only gives you marginal improvements in uptime
Network // Carrier // OpenReach // Network
Provider1 Internet <--> <--|
Exchange <--> Cab |-> CPE
Provider2 Internet <--> <--|
the only shared infrastructure is the cable under the street being in the same physical duct, the copper wire electrically terminates in physically different equipment owned by a different company
they also offer a 3g backup on top of those two independent lines, which is completely independent of the physicality of the path of the copper pairs
they'll even let you announce BGP if you want to multi-home your (existing) PI address space yourself
it's not a normal ISP
we're very lucky in the UK that the way the telecoms industry is regulated allows a small techie focused ISP to operate on a national scale, instead of in one town
they would need to be on the same subnet... I don't see how its technologically feasible to implement across ISPs. (though strictly speaking possible with several routing protocols, just extremely unlikely)
TCP Packet Streams are always directed at an IP, and if that IP changes, a new Stream needs to be established. This will cause a disconnect and its no longer a true failover once that has happened.
Applications can be developed to gracefully handle IP changes, but a lot of them aren't.
as for "I don't see how it is technically feasible": read up about BGP and multi-homing: they form the backbone of the internet
(just somewhat unusual on a consumer home connection...)
It'll be better simply because they're better at finding issues and following up on them, but like most ISPs in the UK, they do not have their own infrastructure.
There are three networks in the UK: British Telecom (BT, copper), TalkTalk (TT, copper) and Virgin Media (cable). Virgin Media, in my experience, is the most reliable network but unlike BT it is not available everywhere. AAISP use both the BT and TT networks, and will offer you what is available, or let you choose.
But if there are issues with BT/TT, you're outta luck. You can get, if you like, two lines and have a failover or whatever, AAISP will in my experience support you way, way more than any other ISP.
It’s getting better though. Various smaller towns have access to Gigabit internet at home now, but it’s still a tiny percentage of the population (around 1.67%). https://www.ispreview.co.uk/index.php/2017/09/ultrafast-fibr...
I would say, the UK has 2 major infrastructure networks (OpenReach, split off from BT, formed from the GPO; Telewest:NTL, now absorbed into Virgin Media) + some minor, growing networks (CityFibre).
See https://availability.samknows.com/broadband/ for what is available in your area (may not include other mobile, satellite, fibre providers)
Coming from SF & Sonic's tremendous quest to run fibre in Sunset, the state of broadband in the UK is atrocious. There's 4 street cabs between my house and the exchange, which is 200 metres away, and none of them have fibre (BT are planning to build 2 more).
After the technician came he told me that one of the two phone line wires had been broken off at the exchange.
In other words, there wasn't a complete electrical circuit.
The phone was dead but ADSL still works without even having a complete circuit.
I don't even understand how that can work at all.
ADSL operates completely beyond the audio band[2]. Since it's entirely a high frequency AC signal, with no DC component whatsoever, a break in a wire will just act as a capacitor, reducing the AC signal strength. Since a broken wire is a terrible capacitor, the signal strength will be reduced tremendously, but in your case, not enough to drop the link.
[1] http://www.etsi.org/deliver/etsi_es/201200_201299/20123502/0...
[2] https://en.wikipedia.org/wiki/Asymmetric_digital_subscriber_...
For a funny example of how sensitive some of these links are, just flick a 100m ethernet cable, running at 10G, with your finger. If you're of normal luck, this will cause a temporary changed in the electrical characteristics of the wire, and that "anti distortion" distortion to be temporarily incorrect, causing a interruption in the data!
The phone company (Centurylink) just one day called me, "Hey, we think we see a problem with your line, and we're sending someone over to check it. Is Saturday okay?"
It's the most proactive I've ever seen a huge ISP be, and it really impressed me. Almost as much as getting nearly my full rated speed out of a single wire.
But I cynically wonder if it didn't have something to do with my contract ending and the price nearly doubling, leaving me free to jump to the other provider.
It worked, though. I'm still with them. It doesn't hurt that the other provider is Comcast...
I used to work for a private TelCo, so checked all my inside wiring, then had a friend call in a trouble report, and it took the damn company 3 weeks! to clear the trouble, because their line test equipment indicated the line was fine.
After reading your post, I'm guessing it was a barely broken/corroded part of a pair in an outside "B" (connection) box, as I live within 1/4 Mile of the ocean.
I've always wondered if it's real, or one of those funny stories with a technical punchline. It seems feasible.
I'm not able to find a definitive source, but it could be the following, which I have also heard from a retired BT employee:
"It's common practice in England to ring a telephone by sending extra voltage across one side of the two wire circuit and ground (earth in England). When the subscriber answers the phone, it switches to the two wire circuit for the conversation. This method allows two parties on the same line to be signaled without disturbing each other.
Anyway, an elderly lady with several pets called to say that her telephone failed to ring when her friends called; and that on the few occasions when it did ring her dog always barked first. The telephone repairman proceeded to the scene, curious to see this psychic dog.
He climbed a nearby telephone pole, hooked in his test set, and dialed the subscriber's house. The phone didn't ring. He tried again. The dog barked loudly, followed by a ringing telephone.
Climbing down from the pole, the telephone repairman found:
a. The dog was tied to the telephone system's ground post via an iron chain and collar.
b. The dog was receiving 90 volts of signaling current.
c. After several such jolts, the dog would start barking and urinating on the ground.
d. The wet ground now completed the circuit and the phone would ring."
https://www.linguee.de/deutsch-englisch/uebersetzung/der+hun...
Ha!
Maybe they should replace the copper with Damp Twine to the Node.
It would be really interesting to create a low-throughput fallback network for neighborhoods using something like this. Though I suppose RF or optical are still quite a bit more practical.
You'll never justify your choice of "wet string" as medium of choice when things go south.
A pickle might work too.
People will do literally anything to avoid pulling fibre and "sending multi-hundred-gigahertz surface waves along rotten old voice copper" is apparently one of them.
This article might be helpful: http://www.kitz.co.uk/adsl/adsl_technology.htm
I do wonder about impedance matching here. Traditional phone lines apparently have a characteristic impedance of either 600 or 900 ohms. That pair of wet strings look to be separated by about the right distance to produce impedance in that neighborhood, or maybe the line length is tuned to eliminate reactance. It isn't mentioned but I suspect that RevK understood this.
> One of the key aspects of the technology is its ability to adapt to the length and characteristics of the line on which it is deployed.
The vertical line is when the connection spontaneously resynced, and a new speed was attained based on the new conditions of the line.
For this particular customer, you can see that tones 410-460 show no transfer at all. This causes a reduction in speed, since those frequencies couldn't be used.
https://en.wikipedia.org/wiki/Reed%E2%80%93Solomon_error_cor...
As I understand it, the endpoints test a range of frequency blocks (or "bins") and only use the ones where there is sufficient signal-to-noise. This is dependent on line conditions.
I'm still amazed that it works at all, but I guess that does show how fault tolerant ADSL is...?