| Slow Modem Cause #1 | | | | One explanation is SNR (Signal to Noise) ratios. |
| Unlike the old dial up modems, DSL modems use | | | | Noise caused by electromagnetic interference |
| a different frequency range to the human voice | | | | from electrical devices degrades the signal |
| that is transmitted at 4KHZ and below. This 4KHZ | | | | strength. Generally speaking, evenings are the |
| band is also known as the base band. DSL | | | | worst time for line noise because many people |
| modems use the broad band frequencies which | | | | are home using electrical equipment such as |
| are in the 4KHZ to 4MHZ range allowing them to | | | | televisions and air conditioners. There is little a |
| provide higher bandwidth and to work | | | | user can do about a high SNR , however, the |
| simultaneously with normal telephone voice calls. | | | | phone company can be contacted for a line test |
| Interference between these frequencies can | | | | to be done. In many cases components of the |
| cause modem performance problems. A DSL | | | | line leading into the home can also be replaced to |
| filter(s) can be installed in order to prevent | | | | help reduce noise. |
| interference between the home telephone(s) and | | | | Slow Modem Cause #4 |
| the DSL service. | | | | Another possible contributor to slow modem |
| Slow Modem Cause #2 | | | | response may be backhaul oversubscription by |
| Another common problem experienced by DSL | | | | the service provider. Backhaul oversubscription |
| broadband users is one of attenuation. Attenuation | | | | means that the connection between the |
| is a term used to describe the reduction in signal | | | | exchange and the core provider network has |
| strength, as distance increases so does | | | | insufficient capacity to carry all the DSL |
| attenuation. The level of attenuation determines | | | | subscribers together at full load. This may seem |
| the speed that you will ultimately receive from | | | | unhelpful at first, but this strategy helps to keep |
| the DSL service. | | | | DSL line costs down. |
| | | | | The contention ratio is the definition that service |
| It is true, however, that attenuation should be | | | | providers use to describe the number of users |
| reasonably constant given that the distance | | | | that will be sharing a backhaul service. The lower |
| between your home and the service provider's | | | | the contention the lower the chances that you will |
| exchange doesn't change. But some users | | | | share infrastructure with other users. For example |
| experience different levels of performance during | | | | a contention of 20:1 is better than 50:1. Some |
| different time periods throughout the day. So | | | | business class DSL services offer a contention as |
| what causes varying degrees slow modem | | | | high as 1:1 which means that the line will be |
| problems? | | | | guaranteed all the provisioned bandwidth between |
| Slow Modem Cause #3 | | | | the modem and the core network. |