Galaxynet :: I can't connect at 56k
Many situations can render 56-kbps technology useless--and none can be
foreseen until you try it out. It's even possible that your next-door
neighbor gets 56k rates while you're stuck with the 35-kbps analog limit.
Which central office you get routed to and the quality of your phone lines
will greatly affect how well 56k will work for you. The following
information will explain how 56k technology works and what could go wrong,
preventing you from seeing faster speeds.
56k "Techno-babble" Simplified
The 56k v.90 specification takes advantage of nuances in the way the phone system
is designed. In a standard call between two modems, your data must be
translated into analog "tones" before it can be transmitted across the
telephone network. This translation is called the digital-to-analog
conversion. Once your data reaches a telephone company's central office,
it's translated back to digital form by a coder/decoder (codec) for
transmission across the phone company's digital backbone. Unfortunately,
because the telephone network contains some random noise, the
analog-to-digital conversion is only an approximation of the original
digital signal. To ensure that data remains readable despite the effects of
this quantization noise, transmission rates are currently limited to about
53 kbps.
However, because most Internet service providers (ISPs) connect directly to
the phone company's digital backbone using routers, data coming from an ISP
never need undergo an analog-to-digital conversion. Instead, the data can be
encoded (using pulse code modulation or PCM) so that it remains entirely
digital until it gets to the central office. Once it arrives, the data is
put through a digital-to-analog conversion before being sent across the
analog phone lines to your modem. And, because digital-to-analog conversions
aren't affected by quantization noise, the result--in theory, at least--is
throughput as high as 56 kbps from the ISP to you.
The bad news is, anything that adds noise to the telephone line (such as
caller-ID boxes, answering machines, and cordless phones) or causes an
analog-to-digital conversion between your ISP and your modem lessens the
transmission's performance. Worse than that, if there's nasty noise on the
phone line, your only solution may be to move. Scream all you want, but the
telephone company is obligated only to provide you with a clean enough line
to get 4,800-bps data rates. But those aren't your only potential
troubles.
The Communication Cops Set The Speed Limit
Though your modem says it's "56k," you won't get throughput that fast,
thanks to a speed limit set by the FCC (Federal Communications Commission).
Sending a signal down a telephone wire requires electrical power. But the
more power you apply, the greater the chance of a problem called "crosstalk".
You've encountered this annoyance if you've ever heard other people's
conversation during a phone call. To help prevent crosstalk, the FCC limits
the amount of power that phone companies can use to send signals over the
network. And this limit on signal strength limits data throughput to a
maximum of 53 kbps, regardless of what your modem can actually deliver. The
FCC is currently reviewing this ruling and may overturn it later to enable
true 56-kbps modem connections... but don't hold your breath.
Office PBX systems
If you have to dial 9 to get an outside line, your office uses a digital
PBX, or Private Branch Exchange, telephone system, which means you also won't be able to achieve 56k rates. A
PBX system incorporates a codec that performs an analog-to-digital
conversion so that your calls can be stored digitally on magnetic media,
such as hard disks. Though this system gives you some great features, such
as employee extensions and call forwarding, it also limits your 56k calls to
a maximum throughput of about 35 kbps.
Noisy POTS
No, we're not talking about cookware. Plain Old Telephone Service (POTS) is
supplied to your house via analog copper wires. Digital lines don't suffer
from noise problems, but the analog wires between the phone company's
central office and your home are a different story. If you hear buzzing or
static when you listen through your phone's headset, chances are you won't
be able to achieve optimum modem speed. Caller ID, answering machines, and
cordless phones can add even more noise to your line. To minimize the hum
try disconnecting these types of devices one by one and listening again to
determine which, if any, are the source of the problem. If this doesn't
work, your line noise may be caused by nearby power lines or other
environmental or structural factors. In that case, call the phone company
and complain (good luck).
The Central Office Switches
Connections between local central office (CO) switches can sometimes be a
problem. Old equipment may require analog termination, resulting in an
analog-to-digital conversion as the call goes through to the next switch. If
a local call to your Internet service provider gets routed through these
"partially analog" switches, you'll lose 56k capability. If that happens,
the telephone company may be able to tell you which type of switches your
call gets routed through on the way to your ISP.
When you make a long-distance call, you can be sure it's traveling only
through digital switches. The long-distance network in the United States is,
thankfully, a fully digital system. Transcontinental calls, however, use
digital ADPCM encoding for voice compression, which doesn't work with 56k
PCM encoding. So you won't be able to get the higher throughput rates when
calling another continent (just in case you were thinking of calling Germany
with your modem).
The Phone Line at your House
A number of problems can occur as data makes its way from the local central
office to your home. Older telephone lines connect directly to the switch at
the central office, and newer lines go through a digital loop carrier (DLC).
These devices can combine 96 separate lines into one before they reach the
central-office switch. By using DLC, the telephone company doesn't have to
bury as much expensive copper wire, which saves money and increases
connection reliability. But DLCs can wreak havoc with 56k. If the DLC is
digitally connected to the switch, no problem; but if it uses a universal
connection, an analog-to-digital conversion will occur, rendering your
modem's 56-kbps capabilities useless.
There may also be a "pad" between you and the central office. A pad balances
the volume on both ends of the line when you make a call. If the pad occurs
before the signal is converted to analog, you'll see only a slight
degradation in 56k performance. But if you encounter an analog pad between
the central office and your home, up crops another analog-to-digital
conversion to sabotage your 56k connection.
Some local lines also run through an amplifier called a "load coil" to boost
the signal rates across longer distances. Load coils cause some signal
distortion and will detrimentally affect your modem's 56k throughput
potential. Many of the current 56k modems on the market will "fall back" to
28-kbps or 31.2-kbps rates when their signal travels through a load
coil.
The Battle of the Protocols
On February 5th, 1998, the International Telecommunication Union (ITU),
headquartered in Geneva, Switzerland, announced that a 56k standard had been
defined. The ITU called this new standard v.90. This new protocol is what
Galaxynet's 56k servers are using. Any ITU v.90 compliant modem should have
no trouble connecting to Galaxynet, barring any line condition problems as
mentioned above.
Before February of 1998 (and a even a little after), there were two
standards offered by two different chip manufacturers. Rockwell developed
the K56flex protocol, and 3Com/USRobotics developed the X2 protocol. Faster
speeds were available over the 33.6-kbps modems, but the two protocols were
incompatible. This meant that only a K56flex modem could connect to a
K56flex server, and an X2 modem could only connect to an X2 server. If you
had one protocol in your modem, and your ISP has the other protocol, you
were out of luck, and would only connect at 33.6-kbps or less.
In 1997, the Internet was still on a huge popularity roll. People were
buying computers for the sole reason of getting on the Internet. Computer
manufacturers put these non-standardized 56k modems in millions of
computers, and using the relative speed as a selling point. The only
problem with this is the two competing protocols. In 1997, the ITU was
still looking at both K56flex and X2, and hadn't adopted a standard
protocol. This led to people trying to use their K56flex modem to connect
to their X2 ISP, and being disappointed at the results.
If you have one of the old non-standard 56k modems, hope may not be lost.
Many of the manufacturers of K56flex and X2 modems offered free "upgrades"
or "uptrades" if you bought your 56k modem after a certain date. An upgrade
allows you download new firmware which you copy to the ROM chip on or in
your modem with a flash program. An uptrade requires you to send the modem
back to the manufacturer, and they will send you a newer v.90 modem.
Whatever the case, you should check with your modem's manufacturer to see
what your upgrade path is.
If you need to know who manufactured your modem and you're running Windows
95 or 98, you can do so through the Modem control panel. While disconnected
from the Internet, double-click on My Computer, then double-click on Control
Panel. In the Control Panel, find "Modems" and double-click on it. At the
top of the Modem Control Panel window, click on the "Diagnostics" tab,
select the COMM port your modem is on, and click the "More Info" button.
This will display the identification information (ATIx) stored in your
modem. |