Your broadband modem or router will likely have a page in it’s web interface listing your line statistics. These are often used to judge the quality of your line. This page attempts to explain the terms used.
(AKA Signal to Noise Margin or Signal to Noise Ratio)
This is the relative strength of the DSL signal to noise ratio - the higher the number the better for this measurement. 6dB is generally the lowest dB manufacturers specify in order for the modem to be able to sync. In some instances interleaving can help raise the noise margin to an acceptable level. Generally speaking, as overall bandwidth increases, your signal to noise ratio decreases.
Note: there may be short term bursts of noise on your line that may drop the margin, but due to the sampling time of the management utility in your modem/router, will not show up in the figures.
This is a measure of how much the signal has degraded between the DSLAM and your modem/router, and is largely a function of the distance from the exchange (bigger distances mean higher attenuation). Maximum signal loss recommendation is usually about 60dB. The lower the dB the better for this measurement.
Note: From a user perspective, there very little you can do to change the line attenuation of your current connection.
The actual service ATM data rate that your ISP has provisioned, plus bandwidth to cover the overhead.
(AKA Sync Rate)
This is the maximum rate at which your modem can connect to the DSLAM if there was no service provisioning limiting the bandwidth. The higher the number the better.
How much power your modem (upstream) or DSLAM (downstream) is using. Maximum recommended is about 15dB. The lower the power the better for this measurement. Not all modems have the ability to provide output power.
Occupancy is the percentage of line capacity used. Each DSL line is capable of a certain maximum speed or “capacity” dependant on line distance and other varying factors. The occupancy is an expression of your current sync rate setting over your maximum capacity. There are occupancy rates for both upload and download. The lower the figure, the better. Because of error correction and other factors in the DSL protocols, a margin is required so that a connection can be maintained under varying line conditions. If the occupancy approaches 100%, any interference can cause the ADSL sync to be lost. A useful measurement to monitor when sync problems occur.
CRC (or Cyclic Redundancy Check) is a method of detecting errors in data transmission. A high CRC count in itself is not really cause for alarm. However, any increase in CRC errors after your initial connection is established is a problem and usually points to a physical issue somewhere between the modem and the DSLAM.