TELECOM Digest OnLine - Sorted: Re: DSL Speed

Re: DSL Speed

Choreboy (
Mon, 20 Jun 2005 15:18:33 -0400

Robert Bonomi wrote:

> In article <>,
> Choreboy <> wrote:

>> On dialup, the farm couldn't negotiate modem speeds quite as fast as I
>> could in town. I assumed the limitation was in the wire.

> It is, and it isn't.

> How far can you yell, and be heard? How far can you talk on a radio,
> and be heard?

It seems to me that dialup and DSL would be analagous to two ways of
yelling across a field; like two ways of yelling, DSL and dialup use
the same medium.

Naturally, Walter Winchell could speak faster on the radio than FDR
could address a crowd outdoors without loutspeakers because FDR's high
frequencies wouldn't reach the audience. If Winchell had a way of
yelling by which he could stand without a microphone and read the
audience a newspaper article in the time it took FDR to say, "We have
nothing to fear..." that sounds like saying DSL can be 50 times
faster than dialup simply because it "yells" differently. I wish I
knew more about it.

>> That's why I was amazed to see that DSL seems to use the wire in the
>> same way as dialup. Was I wrong to think the reason dialup data
>> rates were slower at the farm was that the wire to the CO is
>> longer?

> "Sort-of". It wasn't the actual _length_ of the wire. If you build
> the wire differently, you will get different effects
> over the same length of wire.

Think what would have happened if RG-59 hadn't been invented.
Everybody would have used RG-6, which looks nearly the same but
attenuates uhf much less. With better reception there would have been
more uhf stations and less demand for cable.

> One of the things that goes on, when you run a _pair_ of wires for any
> distance is that there is a capacitance between the two wires. this is
> proportional to the length of the run, inversely proportional to the
> distance between the wires, the thickness of the insulation, and a
> number of other factors. Capacitance between the signal-carrying
> leads has the effect of 'blurring' the signal. which puts a limit on
> how fast you can "effectively" change signal levels, to pass
> information from one end to the other.

> The _methodology_ used to accomplish the signalling determines where,
> and to what extent, that 'blurring' degrades the transmission.

> DSL _does_ suffer degradation with distance, just as analog POTS
> modems do. If you have 15-18,000 feet of wire between you and the
> C.O., you will get much slower maximum rates than if you are less than
> a thousand feet from the C.O.

> DSL uses a differnt _kind_ of signalling -- which calls for
> differently designed transmitters and receivers -- to get the higher
> data rate on the bare wires.

>>> This is how DSL works, it bypasses the _voice_ switching gear. It
>>> uses just the 'bare wire' between the telco C.O. and the customer
>>> premises. The special eqipment in the C.O. puts a *different*kind*
>>> of signal on the wires, that the "DSL modem" at the customer
>>> premises understands, and the 'modem' at the customer location does
>>> 'something similar', to communicate back to that special equimpent
>>> at the Telco offices.

Between the CO and the customer, isn't voice service just bare wire?
Are there inline amps? If so, they could preemphasize high

I don't understand what kind of signal dsl uses to carry so much more
data than dialup without needing broadband cable.

>> What's the downside for the telco? With the right pricing, I think
>> they could tap a huge market for increased bandwidth.

> Connected to _what_? "Multi-megabit bandwidth" to the C.O. is
> -useless-, unless there is "something interesting" to connect to.

> Who needs the capability for a dozen or two (or more) simultaneous
> voice telephone calls from their house? For anything other than
> voice, you have to have that 'something else' available for access at
> the point that that high-capacity circuit from the customer premises
> terminates.

So many people have more than one phone line that I must dial ten
digits to call across the street. At times, a family might benefit by
being able to talk on several channels while keeping others open.

> Getting _to_ the C.O. from the customer premises is the 'cheap' part.
> Whether it is POTS, or DSL, or whatever. Amortizing the equipment
> over, say, 5 years, you're talking about circa $3-5 dollars/month.
> The 'wire' cost, amortized over the useful life (50 years+) of the
> wire pair, is of the same order, maybe a bit lower.

> All the rest of the money goes towards "what to do with it, _after_ it
> arrives at the C.O." For voice, to calls to a number in a different
> C.O, you have to have inter-connects to get the call _to_ that C.O.
> If there isn't a direct trunk circuit, you have to go through another
> layer of switches (called "tandems") -- at least one, possibly several
> -- to get to the destination 'local' switch. 7 figure price-tags, per
> unit.

> Same thing connecting to the 'internet' -- you generally have to 'pay
> somebody' to pass your traffic on to the rest of the world, Costs for
> that depend on "how much" traffic you have. More traffic, more
> cost. and bigger, more expensive equipment.

At one time, automobiles were for wealthy people who lived near
factory-operated dealerships. Going sixty was sport. The ability to
go twenty would have made a big difference at farms, where distances
were great and public transportation not available. Price and repair
obstacles kept farmers out of the market. Henry Ford spent years
developing a vehicle suited to rural budgets, roads, and mechanics.
Once it was available, it became so useful that it revolutionized
rural America. I think at one point Ford was selling more vehicles
than all the other brands in the world.

If you have a second phone line for your modem, a $25 ISP, Direct TV,
and perhaps other Bellsouth services, they will give you a price where
going to DSL will lower your costs. However, for somebody whose only
cost is $100 a year for an ISP, DSL would add $500 to his annual
budget. Many feel they can't afford it, just as farmers before the
Model T felt that they had no choice but to stick with slow,
inconvenient horses and wagons.

You say internet costs depend on how much traffic you have. With DSL
the customer can download about 150 kB/s. Suppose budget DSL were 10%
as fast. That would still be three times faster than dialup, and the
phone would be available. Budget customers would add much less to
peak use, and they would probably download less in the course of a
week; with one-tenth the speed, you're less likely to download big
files you don't need.

I think there's a big untapped market for DSL, and it could be
profitable at a low price. Cadillac did not introduce the Model T,
and I guess Bellsouth doesn't want to offer existing customers
something cheaper.

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