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Line Attenuation
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| 20dB and below | Outstanding |
| 20dB-30dB. | Excellent |
| 30dB-40dB | Very Good |
| 40dB-50dB | Good |
| 50dB-60dB | Poor and may experience connectivity issues |
| 60dB and above | Bad and will experience connectivity issues |
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SNR (Signal to Noise Ratio)
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| 6dB or below | Bad and will experience no line synchronisation or intermittent synchronisation problems. |
| 7dB-10dB. | Fair but does not leave much room for variances in conditions. |
| 11dB-20dB. | Good with little or no synchronisation problems |
| 20dB-28dB. | Excellent |
| 29dB Or above | Outstanding |
See the Phoneworks ADSL Troubleshooting page for more information on these figures.
If you have a poor SNR figure (6 or less) the first thing to check is if the fault is on your premises. To find that out performa Line Isolation Test. If that makes no difference it’s most likely a fault on your telephone line in between your premises and the Telephone Exchange so consult your ISP*.
* ISPs are notoriously reluctant to organise a technician to check the line because it costs them money whether a fault is found or not so it may often take some negotiating to get the problem fixed. They may also recommend a change of profile (ie sacrifice some performance for stability) which is often an acceptable workaround.
Tip: If you’re still unsure whether a fault lies with your modem or with the ISP or the phone line, the only way to be sure is to try another modem or try your modem at another location that is known to be fine.