Hey everyone, this post is going to be a bit long, weird and complicated, I'll try to explain the problem in detail with some pictures, so please bear with me.
I've been having an issue with my DSL line for more than two years now, the main culprit is electrical interference, which is heavily tanking down my SNR. I am with IDM 4mbps. The first thing I thought of doing was to install an external phone cable from the phone box, directly to my room, been procrastinating and left it untended for a long time since the modem was syncing at full speed but with critical SNR. We have our own two stories building, there is a shop at the ground floor, the weird part is when this shop electricity is on, it will further increase the interference. This shop is sharing the same electricity meter with the house. Five months ago I noticed the modem is syncing at 3600 downstream rate to maintain a stable connection with 6.0db SNR, so I decided to install the external cable, I used a high quality D-Link CAT 6, directly from the phone box, went inside an isolated tube with no other cables, this tube goes upwards to the rooftop, then to my room, installed the exposed part inside a plastic/electrical tube to protect it from sunlight. There was some improvement, the modem now syncs at full speed but still with critical SNR. Another weird thing is that there are literally two modes for the SNR that keeps switching every once in a while:
Mode A:
Which is heavily affected from both, state and sub-power electricity. When electricity is off, I have 21db down/14db up, 6.0db down, same for up when electricity is on. Switching the modulation from ADSL2+ to G.dmt increases downstream SNR by 2 to 3, therefore 8 to 9db.
Mode B:
Which is significantly less affected from electricity, however this one varies between state and sub-power, on state electricity, the lowest it goes down to 12db, highest is 16db, while on sub-power, the interference is minimal. Also on this mode, the upstream SNR is always 8.0db which is lower by 6db compared to mode A. I am not sure if the central is switching me between two profiles back and forth, nevertheless, electrical interference is destroying the SNR for both modes.
We have a complete box/patch panel which contains 10 telephone lines installed inside the building, Ogero offered it as a compensation back in 1996 because they wanted to install a cabinet (the small/grey one) in our yard, which is 10 meters away from my room.
That is the box from the outside which contains 10 phone lines. The four punched down pairs are the two active phone lines.
That is from the inside.The first pair, white and blue is the one I am using for the DSL, the white and yellow pair is the one for the shop at the ground floor, it has no DSL activation.
That is the phone box where the lines are distributed from.
Here you can see the installed CAT 6 (the grey one) cable. So I started to think outside the box, I did cut the other phone line, as expected, nothing changed. When I switch off the electricity meter, the interference is gone. When I terminated the line in my room, I got electrocuted twice when I touched the bare copper, I had to wear a pair of shoes, this confirms that there is electricity flowing within the cable.
The question is, how is the line still picking up interference after the external installation? I called Ogero (Before Kreidieh took over) and they told me that if it is electrical interference, you have to bring an electrician, I talked with two electricians, one told me that the interference from the shop is only a coincidence, so I didn't bother talking with him again. The other one told me that he has to come and take a look. However he has the usual trend of, I'll be there at 2:00 and no one will show up. I talked to a guy who, as he claimed, experienced in DSL installation, he was speechless and scratching his head when I told him about the external installation.
At first I was okay with the line handling the 4mbps, but now with the upcoming speed increase, it will rely on how much your line can handle, so I might not see any increase due to the low down SNR. Also with the upcoming FTTC project, it will still rely on copper, so I have to fix this problem for good.