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