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Grandma's Phone, DSL, and the Copper They Share (hackaday.com)
szczys writes: DSL is high-speed Internet that uses the same twisted pair of copper wire that still works with your Grandmother's wall-mounted telephone. How is that possible? The short answer is that the telephone company is cheating. But the long answer delves into the work of Claude Shannon, who figured out how much data could be reliably transferred using a given medium. His work, combined with that of Harry Nyquist and Ralph Hartley (pioneers of channel capacity and the role noise plays in these systems), brings the Internet Age to many homes on an infrastructure that has been in use for more than a hundred years.
Did I accidentally wake up in 1999?
It's not a judgement on your method of communication, but a recognition that a telephone from 80 years ago will still work on the same system. Remarkable.
Would have been nice if DSL never existed, dial-up would be the norm and websites would not be bloated, no social media or other bullshit.
Instead companies keep profiting while not investing anything into upgrading the rotting copper.
Looks like the new owners of Slashdot are also failing to combat the biggest problem faced by the site for the last few years.
Junk making the front page that talks to me like I don't already work in IT or understand how common household technologies work.
Actually it won't. Not unless your grandmas phone was touch tone and 80 years ago it certainly wasn't.
You may not be able to place calls with a rotary phone any more, but you certainly can receive them. The system still works, its just the dialing methods have changed.
You may not be able to place calls with a rotary phone any more, but you certainly can receive them. The system still works, its just the dialing methods have changed.
Actually you can, atleast in the UK. Pulse dialling is still supported by the national phone provider.
Claude Shannon was truly one of the unrecognized geniuses of his time.
He was an amazingly brilliant man who got very little of the recognition he deserved. Virtually ALL modern-day communication depends directly on the algorithms and information theory practices he invented. He's quite rightly known as the "founding father of electronic communications age".
He was still alive when I was in tech school, quite literally a "living legend".
Just cruising through this digital world at 33 1/3 rpm...
You can in France too.
Stupidity is the root of all evil.
Many *MANY* years ago I was working as a software engineer at Philips Research in the early 1980's when they were looking into ISDN systems somewhat like DSL for the UK market - the business of sending anything over twisted pair copper is a nightmare. I wasn't directly working on the electronics (I was doing software) - but I shared an office with people who did...and they had a heck of a time characterizing the wires that their signals had to go down.
As I recall, the problems mostly come where one wire is spliced into another. Much of this infrastructure was put in the 1900's and it's horrible. Sometimes wires are just twisted together and capped, sometimes twisted and taped, sometimes twisted and just left open to the elements, sometimes they are soldered. Sometimes the places where the wires are joined gets wet when it rains. Sometimes the tightness of the twisted wire connection depends on the ambient temperature. The amount of cross-talk between wires is all over the map as different kinds of insulation was used (and much of it has degraded over the years). At the subscriber end, there were all kinds of phones being used - plus ugly stuff like "Party lines" (where two houses share a phone line!) that had been abandoned leaving extra wires in the ground that were still connected to the network.
All of those things affect the ability to get a decent amount of bandwidth down a wire that was never designed to do it. So the electronics has to be smart about the signal being reflected at each splice down the line and causing 'echoes', and designing affordable circuitry to detect and cancel those echoes was a nightmare. The amount of attenuation you'll get is all over the map - everything has to self- adjust and monitor to give it any chance of working.
So, as poor as DSL can be - it's a miracle it works at all over crappy old telephone wires.
-- Steve
www.sjbaker.org
For an 80 year old phone it half works, for a 20 year old phone it completely works, but there isn't any particular reason we'd want it to still work.
I guarantee the US can, too, as it's all computers now.
My dad refused to give up his rotary (a phone company rental bakelite black, at that) because the phone company continued to want to charge extra for "premium" touch tone service, even long after it was actually a drag on them.
Last time I had a land line, around 2010, it was rotary-only, so whenever I had to use a menu, as to pay a bill, after dialing I would switch the phone to touch tone.
(-1: Post disagrees with my already-settled worldview) is not a valid mod option.
My grandmas are dead, you insensitive clod.
"I'm so moist I'm sticking to the leather." -Kermit the Frog on The Late Late Show
Not unless your grandmas phone was touch tone
Pulse dialing still works nearly everywhere. Indeed, some people are skilled enough to do pulse dialing by flashing the hook the required number of times.
Like me.
Get on my level.
--
BMO
HOWTO: http://www.oldskoolphreak.com/...
And I stopped reading bullshit article right there...
Chas - The one, the only.
THANK GOD!!!
Yeah as of now I have POTS with phone > DSL modem > router.
They are trying to get me to switch to POTS no phone > DSL modem with voip bridged back to pots line > router
As of now I can lose phone without losing DSL and I can lose DSL without losing my phone.
So then If my dsl goes down I lose both internet and phone.
They've been advertising it as fiber optic phone service.
Minimum threshold fixed. Thanks!
I disagree.
Not everyone here studied this stuff. Some of us are self taught, or are experienced in other fields (software, systems admin) ...etc.
So, having stuff like this is enriching to some here, and relevant to the site ...
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