| (If
you see a connection speed of 38400, 57600, or 115200, don't be fooled -- that is the
serial port speed between your computer and your modem, not the speed between your modem
and the remote modem. To report the modem-to-modem speed, your modem probably needs a
different initialization string. Consult your documentation.)
Note: Reported initial connect speeds won't necessarily be
dependable or even comparable from modem to modem or location to location. The reason is
that V.34 modems can (and often do) speed shift up and down after the initial connection,
and do so in a manner that is dependent on the particular connection as well as the
particular equipment (including firmware versions) at each end. (See "What are
"fall-back" and "fall-forward"?") Some modems connect at a more
conservative speed and then quickly upshift as conditions allow; other modems connect at a
more aggressive speed only to quickly downshift (or worse, lose performance due to
excessive errors). Another problem is that software may report the receive speed for
certain modems and the transmit speed for other modems, which can be substantially
different. (See "What are split/asymmetric speeds?") Unfortunately, it is not
possible to monitor the actual modem speed during the connection for most modems.
Regardless, the only thing that really counts is net throughput, which can be measured by
many communications applications.
- If you rarely get 26.6 kbps or 28.8 connects, the reason is
almost always a result of phone line quality. 28.8/33.6 modems are pushing the limits of
today's telephone system. Getting 28,800 bps connections requires pristine telephone line
conditions end-to-end. Here are three paragraphs, which are from a paper entitled "Of
Line noise, The Phone Company, and Your Modem" by Patrick Moore, Supra Corp., (They
make modems)
- If you consistently connect at 26400 or above, there may not
be much that you can do to go faster -- it's simply not possible to achieve the highest
V.34 speeds on many phone circuits. (This is not false modem advertising -- 28800 modems
are designed to wring as much speed out of the actual real-world connection as possible,
and 28800 or higher speed is only possible on a near-perfect connection.)
- Repeatable results with V.FC/V.34 modems on real-world phone
lines are sometimes difficult to obtain. Unlike V32.bis modems, V.FC/V.34 modems will
actually modify their data coding (symbol rate) and transmit levels during the connect
phase. Very minor differences in the phone line can lead to quite different results.
- A 28.8K connection on some real-world lines may not occur very
often, if it occurs at all. Preliminary testing in the lab indicates that
"normal" phone line attenuation makes a 28.8K connection difficult even in the
absence of line noise. This is not surprising considering that the V.FC & V.34 coding
schemes are relying on the bandwidth of the phone system being greater than what is
actually available in some areas. Very high-speed connections assume that there is a
substantial amount of digital technology in the system (thereby normally increasing the
usable bandwidth). Some users are going to find that their local phone system effectively
limits them to 16.8K or 19.2K.
- Both the originating and the answering modem are adjusting to
their line conditions during the connect phase. The fact that a connection to a given
modem at a given location occurs at a lower rate (19.2k for example) may have nothing to
do with the modem the call is placed with, or the location it is placed from, as the modem
on the other end may be adjusting the baud rate down.
- For the above reasons, many people will never see 28.8 or even
26.6 CONNECTS with their 28.8 modem. The easiest way to find out if its your phone line or
your modem is to find someone who usually gets 26.6 or 28.8 connects, and try your modem
on her system, or his modem on your system. You will most likely find that the problem at
your end is phone-line related. If you consistently connect at lower speeds (e.g., 24000
or even 21600), there may still not be much that you can do.
- The part of the telephone system which you may be most able to
improve is your telephone premises wiring. If you rarely get 28.8 or 26.6 connects, try
the following:
- Watch out for heat. Some modems work better cold than hot, and
vice versa. Generally speaking it is a good idea to make sure that the modem does not get
too hot.
- With a PC Card (PCMCIA) modem in a laptop computer, try
disconnecting the computer from AC power and running on battery alone.
- If you have your modem connected to the phone line through a
surge suppresser, try it without the surge suppresser. Many surge suppressers can
interfere with modem communications.
- Make sure that your serial port is locked at 38400 or higher
(57600 recommended). This is usually set within your comm application, not the Windows
Control Panel
- If that doesn't help, listen carefully to the quality of your
voice connections. Note that you must dial a known quiet number, since many otherwise good
phone lines exhibit excessive noise until you actually connect. (Dialing a single digit is
not enough.) After you connect, if you hear more than very faint hiss and/or hum, then you
probably have a line problem.
While a quiet line is important, there are other line problems that can reduce your speed:
bandwidth (frequency response), distortion, etc. It is difficult to test for these
problems without proper test equipment, but it's still a good idea to listen carefully for
audible problems, particularly if you can find a number that will send you test tones.
- Premises Wiring . . . Often faulty premises wiring, bad phone
jacks and plugs, cheap phones, old/antique phones, or too many phones or other devices
cause problems. Here is how to determine if your premises wiring or equipment is affecting
your CONNECT quality. Find the telco wiring block where all your premises wiring connects
-- it will usually be outside or inside of your house near where the phone line comes in.
Run a good quality twisted pair phone cable directly between the block and the phone jack
that serves your modem, routing so as to avoid other electrical wiring and devices -- and
then disconnect all other premises wiring from the telco block. Note that only two
conductors are necessary in modern residential systems (normally green and red). If this
gives you faster connects, then your premises wiring or your phone equipment is causing
you trouble. Reconnect wiring and phone devices incrementally while retrying the modem to
see if you can find the culprit. Examine each plug and jack, and reseat each several
times. Where visible, inspect the routing of the phone wiring to assure it steers clear of
other wiring and electrical devices. If you find some of your equipment or premises wiring
is contributing to the problem, the recommended solution is to replace or eliminate the
equipment and/or wiring.
- Telephone Co. Line Quality . . . If you determine that your
premises wiring is not causing problems, and you still get low connect speeds, you can try
a few other things like calling a known quiet number and listening carefully -- if you
hear hissing, humming, a radio station or other background voices, you have a line problem
(you may have a line problem even if the line sounds quiet). Reporting noisy conditions
will probably be sufficient to get the phone company to look into the "problem".
You may be able to get them to test and improve your line, but be aware that all they
guarantee to provide is a line meeting voice quality standards, and also they may want to
charge you for the testing if they find no line problem. So you telling them your modem
can't get 28.8 connections probably won't motivate them. However, it has been reported
that the phone company will generally be responsive to fax problems, so report those if
you have them. Your connect speeds will frequently be lower when you are distant from your
telephone exchange , and when your call must pass through more than one exchange.
- You may be told that you need a special "data" line,
more properly called a "conditioned" circuit, which is considerably more
expensive than a standard "voice-grade" circuit. Don't waste your money. All you
need is a good quality "voice-grade" circuit.
HIGH SPEED (28.8 KB/Sec) V.34 MODEMS ON THE TELEPHONE
NETWORK
- The technology of dial modems has reached the point where they
are pushing the theoretical limits of how much data can be passed over an analog telephone
connection. The latest type of high speed modem is built per a standard called V.34. Under
the best of conditions these modems can pass data at 28.8 kb/sec. The data speed that can
be supported on an analog circuit is a function of the bandwidth of the channel and the
noise on that channel. Wide bandwidth, low noise connections, can carry more data than
narrow bandwidth, high noise connections.
- The telephone network was designed to provide a connection
with enough bandwidth so that voices could be heard clearly and that the speakers voice
could be recognized. That's why the bandwidth of a voice channel is from 300 Hz to over
3000 Hz. Noise is inherent in a telephone system and can have many sources. The telephone
company will try to control noise so that it is not objectionable to most people. Any
attempt to increase bandwidth or reduce noise, costs money. So the bottom line is that the
telephone company will try to provide a good quality voice connection at a reasonable
cost.
- The telephone network is designed to provide good voice
service on most connections at a reasonable cost. Any connection can be made up of
combinations of local facilities, multiple switch connections, and multiple interoffice
facilities. Because of these variables, not all connections will be the same. Some
connections will be better than others.
- Modem manufacturers have taken advantage of the fact that some
connections will have higher bandwidth and less noise than other connections. When
connections are ideal, the new modems can run at 28.8 kb/sec. If there is less bandwidth
or more noise, the modem may end up running at a lower speed. These modems are designed to
adjust their speed to deal with less than ideal conditions. As conditions permit they will
run at 26.4kb/sec or 24.0kb/sec or 19.2kb/sec or less. The additional variable is the
modem itself. Some modems will deal with line conditions better than others.
- The telephone company cannot guarantee any minimum speed on
any connection on the telephone network. Some modems deal better with the normal
limitations of the telephone network than others. The telephone company must, however,
ensure that it is providing good quality voice service. Some impairments may not be
detectable with a simple voice test.
Modem speeds have always been a big deal with Internet
Connections. We find that many people can get between 24000 and 28800 connect speeds.
There are FEW (in the few hundreds) that can get true 33.6 speeds. If you are experiencing
random connection speeds to us, most likely it is a problem with the telephone lines, your
modem, or premise wiring. There may not be much you can do.
You can try to set the connection rate for your connec to
cyberbay.net in Dial-up Networking to 57600 or 38400 (Click the configure button while you
are in the properties for cyberbay.net in Dial-up Networking.)
The above paragraphs should explain plenty in regards to
connection speeds. Your connection to us may very well differ from your connection to
another ISP, just like calling to China is different from calling to England. You may
experience different performance levels.
Connection rates also can fluctuate from day to day! Weather
conditions can affect line performance. Your telephone company may be doing work on some
line or switch between your place and our place that could affect your line conditions
favorably or unfavorably.
The basic information that we are trying to convey is that on
our end, everything is set up to receive calls on the specified lines at the posted kbps.
If you dial into a 33.6 line, then you are attempting to connect to our 33.6 port. Whether
you get a 33.6 connection is entirely determined by the factors discussed in the above
articles. |