Media for Re: DSL Speed

Re: DSL Speed

If only I had remembered the right term!

Oops, I was thinking "not coaxial" and "bare" popped into my head.

I'll know to look for something the resembles the sermon billboard in front of a church.

Is it indistinguishable if the customer has a V.90 modem? I think I've read that an RT won't allow 56k dialups.

Does an RT entail an extra A/D conversion?

A carrier vor V.90 must have some very precise modulation. It's amazing that an 8kHz sampling can capture it well enough to be useful.

They can bond copper loops to go as high as 27 Mbps!

Twisting is like low-tech coax. It was advised when using a 300-ohm flat cable from a rooftop TV antenna. I imagine it could help for telephone drop cables.

With one ISP, I kept dropping connections around lunch time. One day I had no trouble. I noticed the mill down the street was closed. The drop line to the guard shack comes from the same aerial terminal as mine. The guard shack would get a lot of calls at lunch time. I wondered if crosstalk from his ring signal was getting me.

Local loop cables (trunk cables?) seem to deteriorate. Phone men seem to look for available pairs when customers complain of noise. I wonder if voltage from nearby lightning strikes might cause pinhole damage to the insulation of twisted pairs, and over the years it gets hard to find a good pair.

I used a DMM to check milliamps. My noise came from a spade terminal in the wall jack. I cleaned off the patina and the noise was gone. Low tech!

At DSL frequencies I would have thought coil impedance would be too high to matter. I don't quite grasp it.

Load coils might be one reason a particular phone sounds distorted at a particular location.

That's what somebody pointed out to me as an inline amp. If I could remember who it was, I'd correct him!

As I recall, a phone man appeared to have an aerial terminal open after I lost phone service one day. He said he'd made a mistake and would try to figure out how to reconnect me.

Across the street, a small trunk line (cable with lots of wire pairs) comes from the aerial terminal down a couple of feet to a fusebox on the utility pole. (I think the telco calls them something besides fuses.) The drop cables come out of that box.

Offhand, that sounds like a stub of 1/4 wavelength. Could the modems could mitigate the problem by the frequency they negotiate?

I wonder how they're modulated.

I wonder if the phone patch box had adjustments to flatten the frequency response. I used to listen to Koss studio headphones (with liquid-filled cushions) plugged into the jack on the front of a stereo. One day it occurred to me that with 220-ohm series resistors, the impedance was too high for 32-ohm phones. I used resistors to make voltage dividers with an output impedance of 1 ohm or so. What a difference!

With a phone line, I guess it's not just a question of impedance. It might need a graphic equalizer.

Could you have gone to the federal penitentiary? Was there a good reason for the law?

With a bow-tie antenna, a good UHF amp, a rotator, and RG-6U, we could receive so many channels that we weren't interested in cable.

Thanks, Neal.