Below you will find guide on how to find out the ADSL line statistics on various models of router, not all routers will display all the information below but you should be able to find the Line Attenuation and the Noise Margin.
SN Margin (AKA Signal to Noise Margin or Signal to Noise Ratio)
SNR is the Relative strength of the DSL signal to Noise ratio. In other words, the volume difference between the background hiss and the DSL signal. On ADSL, the router and exchange will attempt to sync at about 14.5db. Numbers around this are okay, but the lower it goes the worse your signal will be. ADSL2+ uses different tones, and is thus able to sync much lower – your router and the exchange will attempt the reach a figure of around 6db.
Measure of how much the signal has degraded between the DSLAM and the modem. Maximum signal loss recommendation is usually about 60dB. The lower the dB the better for this measurement.
- 20dB and below is outstanding
- 20dB-30dB is excellent
- 30dB-40dB is very good
- 40dB-50dB is good
- 50dB-60dB is poor and may experience connectivity issues
- 60dB or above is bad and will experience connectivity issues
CRC Errors (Cyclic Redundancy Check)
CRC 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 may be a problem and can point to a physical issue somewhere between the router and the DSLAM.
ADSL2+ typically has a much higher count of CRC errors due to the more sensitive nature of the higher speed signals.
How much power modem (upstream) or DSLAM (downstream) is using. Maximum recommended is about 15dB. The lower the power the better for this measurement.
Can I improve these figures?
Unfortunately, these figures are ultimately dependent on a number of factors including distance from the DSLAM/Exchange, the condition of the cabling, the internal wiring within your premises and sometimes other factors such as eletrical noise etc.