Line attenuation and SNR
After our move the adsl internet connection has been less than stable. Sometimes it’s up for a week, sometimes it disconnects 20 times a day. According to the isp this is due to us being 4km from the exchange, which is kinda weird as we only dropped a floor and never had problems before. So now I’m reading into things like line attenuation and dB signal to noise ratio so I actually measure what the hell is going on and if any improvements I make to the indoor cabling have any effect whatsoever. Now if only the cable isp didn’t block certain server ports I’d switch to cable in a heartbeat.
A high SNR (signal to noise ratio) simply means how loud the signal is over background noise. The higher the SNR margin the more stable the connection. You have a strong signal and have plenty of head room to receive faster speeds. Generally you would have a high SNR if you’re on a restricted speed plan eg. 256/64, 512/128 or 1500/256. The faster your connection speed the lower your SNR will be. Generally on unrestricted speed plans like Adsl2+ up to 24mbit the isp will set the SNR margin at which your modem connects generally a range between 6dB to 14dB. This will give you the fastest speed while maintaining a relatively stable connection.
Attenuation on the other hand is a measurement of the resistance to the signal on the line and should never change regardless of speed.
There are many factors which affect both SNR and attenuation. A few are line distance, gauge or thickness of line, quality or age of line, number of bridge taps on line etc.
So now I can start focusing on the latter, one step at a time, as the inhouse cabling is the only thing I can influence myself. And if that doesn’t help… time to start thinking about cable after all.