|
|
Slow Connection Speeds
The speed reported by the modem is the initial connection
speed
The speed reported by your modem when connected to the Internet may be lower
than you'd like it to be. It is important to note that the connection speed
that is reported by your modem is the initial connection speed. After
connecting, adjustments and changes to the speed will occur. The modem may
attempt to speed up (fall forward), but will slow down (fall back) when
excessive transmission errors occur that prevent the modem from sustaining the
initial speed. Some modems are agressive, and attempt to connect at a high
speed then downshift, while other modems connect at a conservative speed and
attempt to upshift during the connection. When a modem tries to
achieve/maintain speeds that are beyond the line's actual capability, you end
up with a lot of errors and speedshifts which result in poor throughput and
performance. See Why Slower may be Faster from modemsite.com for more information.
What is the average speed for a v.90 modem?
If you have a v.90 modem, the average connection speed is about 40-49kbps. If
you have a 56K modem and your connection speed is less than 38kbps, the low
speed is likely due to a bad line condition, multiple A/D (analog to digital)
conversion or Telco issue.
Multiple A/D Conversions prevent v.90 connections
The phone line going from the modem is analog until it terminates into the
phone company's central office (CO) or digital loop carrier (DLC). If there
is more than one analog to digital (A/D) conversion present on the line (see
below), you will not get v.90 connection speeds; instead, you will get
v.34 connection speeds. See A/D conversion check
for more information.
More than one A/D conversion on the line can be attributable to:
- Old equipment Some older switches may
cause an additional analog to digital conversion.
- Pads Pads may be used on the line
to make voice communication the same volume both ends during a telephone
conversation. An analog pad introduces additional A/D conversion. There
are also digital pads which do not affect the connection speed.
- SLCs If your home (or office) is
attached to the Telco Central Office (CO) using a
non-integraded/universal DLC, also known as an "SLC", you will
have more than one analog to digital conversion. If, on the other hand,
the SLC is directly integrated into the digital telco switch, you should
get a v.90 connection unless the options or timing are not correctly
configured by the Telco which would result in poor throughput and
unreliable connections.
Other factors that affect your connection speed
In addition to multiple A/D conversions, other factors that affect your
connection speed include:
- Distance from the Telco
Central Office (CO) If you are more than 18000 ft from the Central Office, you will
get a 33600 connection speed at best. The closer you are to the CO, the
better chance you have of having a higher connection speed.
- Multiplexing equipment This equipment, also known as
Pair Gain Devices, are used to provide a second phone line or increase
the number of customers that can be served can limit the line connection
speed.
- Digital lines Note that while a digital
line will provide a cleaner data environment, it may limit the maximum
speed a modem may attain. There are also different types of digital
subscriber line systems. Some combine many lines into one digital
carrier, others combine only two. The key to having V.90 capability with
one of these is the way the carrier is interfaced into the digital telco
switch or even being connected to a digital switch. If the digital line
does not use an analog to digital interface, a device you can use to
remedy this problem is the Mobile Konnector.
- Sychronization Synchronization issues in
the switching center that causes your modem to repeatedly
"retrain" - probe the line for configuration parameters.
- Load coils or signal
amplifier
These devices are installed on analog portion of line by Telcos to boost
the voice communications but which may also distort the signal and
reduce a modem connection speed.
- Call routing Phone companies may change
the route the call takes at certain times of day to distribute heavy
traffic on the lines. This might also occur during road construction.
This change in routing may introduce an additional A/D conversion on the
line, thereby lowering your connection speed.
- Signal strength Phone companies may also
lower the signal strength on the line during times of high usage.
- Noise on the lines. Caller ID, portable phones,
and answering machines can all add noise to your line, limiting the
effect. Even high-tension power lines in the vicinity of your home, or
near the route your line takes can cause enough electromagnetic
interference to cancel the advantage. Connect a telephone to the wall
jack used by the modem, pick up the line, dial the number 1 to stop the
dial tone, and listen. Do you hear loud hissing, static or voices? Try the
test again after disconnecting other telephones and devices using the
line. Still hear the 'noise'? Before filing a complaint with the phone
company, please bear in mind that the phone company is only obligated to
provide 9600 bits per second on that line, which is adequate for the
business they're in - voice communication. In addition, noisy lines can
also be due to INSIDE wiring. One way to test INSIDE wiring is to
by-pass the home wiring and connect your modem directly to the demarc -
a gray box where the phone service enters the house. If the noise
disappears, then the problem is due to inside wiring.
- Hardware incompatibilities Some modems are not as
compatible with our modem pool than others. For example, we do not
support the v.92 protocol and there are some v.92 modems that do not
work extremely well with our service unless the v.92 is disabled (use
v.90 instead). In addition, older 56K modems using the X2 protocol may
experience problems. The workaround for these modems is to disable the
X2 protocol with a modem initialization string. Note: It is
strongly recommended that you update your modem driver (when updates are
available) as these updates may sometimes improve the connection.
|
|
|
|
