ADSL filters

teraside, I appreciate the calm and sober advice.

When I pick up the phone there is no noise, and I'm starting to believe there is a serious problem with our line.

We get perfect speed on our line, that is 420kBps and routerstats shows a stable 4096kbps speed. We have Verizon, SAIX and IS accounts. The problem is that the line starts to drop and resync on the the router from roughly 19:00 at night till sometimes 22:00 at night - every few seconds. It might even happen at 00:00, but the frequency of the dropping is definitely the worst between 19:30 and 20:30.

Why on God's earth would this be happening? During the day it might happen once or twice, but that will not be a series of drops, just a slight drop which I think is normal. At night it goes ballistic and drops every few seconds.

I thought the filters might be to blame but now I just don't know anymore. I think I might march up to one of the Telkom outlets and go talk to them there.
 
Some advice, don't talk too much about the "line drops" to Telscum, they have a tendency to reseat your line so to say to a speed which is less, like 1024 or just below 4mbps.

If it works fine enough during the day, but not at night, it says something about the line itself, maybe it's moisture that effects the line.

I'm a bit vaak when it comes to SNR and Attentuation values, but send a private message to either Yotch or OUPA MR Nuts and ask them to view this thread, they will give you some advice to test the line a certain way during the day and at night, thereby you can come to a conclusion ;)
 
Yeah, I have mentioned this problem in another thread and im trying to get routerstats to work properly. Although I haven't had time to figure it out. Used the lite version and let it run for a day, but it didn't create a log file >.<

Work is hectic atm, so I will have to put this off for a few days. It just really annoys me that I get home from work and then I can't use the internet for half the night :<

And btw - when I spoke to a Telkom technician on the phone about this problem the first time he mentioned about dropping the line speed, but when I told him it only happened in the the evening he said that dropping the speed won't help. So I'm hoping to get someone out here to have a look at the physical line.
 
Best wishes Cloud ;) Hope you sort it out. You might think about taking a 3G/HSPDA contract out from MTN for backup, the 350mb is about R209 per month, get a pamphlet at an MTN store ;)
 
It might not be related but this happened to me: I also found that certain times of the day that the ADSL line would constantly lose sync. After lots of frustration, including having Telkom look at the line, it turned out that the modem is very sensitive to loads on the electricity supply, so turn on the stove, oven, kettle or heater, and it starts losing sync. It was especially bad during winter. Doesn't make much sense to me since everything is on different circuits, but these things definitely affects my modem. E.g. between 6pm and 8pm when the stove or oven is usually on, the modem will not sync. If I isolate the modem by putting it on a UPS (unplugged), then it works perfectly, no sync loss.

To this day I still can't pinpoint the exact problem, even tested the voltages when these things are turned on, but don't see any fluctuation... maybe it's just a crappy modem after all.
 
ginglung, thats a very interesting theory, i will investigate. Willing to try anything at this point.
 
qinglung said:
It might not be related but this happened to me: I also found that certain times of the day that the ADSL line would constantly lose sync. After lots of frustration, including having Telkom look at the line, it turned out that the modem is very sensitive to loads on the electricity supply, so turn on the stove, oven, kettle or heater, and it starts losing sync. It was especially bad during winter. Doesn't make much sense to me since everything is on different circuits, but these things definitely affects my modem. E.g. between 6pm and 8pm when the stove or oven is usually on, the modem will not sync. If I isolate the modem by putting it on a UPS (unplugged), then it works perfectly, no sync loss.

To this day I still can't pinpoint the exact problem, even tested the voltages when these things are turned on, but don't see any fluctuation... maybe it's just a crappy modem after all.
Click to expand...

@qinglung: Do the following tests and report back on which of the following four configurations are stable.

1) Attach the phone line directly (no UPS, additional lightning protection, microfilters etc.) and connect the router power pack directly to the mains (no UPS).
2) Attach the phone line directly (no UPS, additional lightning protection, microfilters etc.) and connect *only the router power pack to the UPS*.
3) Attach *only the phone line to the UPS* and connect the router power pack directly to the mains (no UPS).
4) Attach both the phone line and the router power pack to the UPS.

If the problem is due to mains interference it might be simple to fix it without requiring a UPS. You could for example just change the external router power pack, connect the router directly to the internal 12V supply from a PC or use a simple mains RFI filter in front of the external router power pack. You need to first determine the source of the problem. It is even possible that the lightning protection/telephone line filter in the UPS is the bringing about the improvement and not the UPS power circuitry.

You could also try to get plots of your downstream noise margin for the four configurations above using routerstats. These should help to determine what is causing the problem. Your downstream noise margin could be hovering around 6dB for example, making the router very sensitive to any power supply fluctuations.
 
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@Yotch: some more info though, I have tried another power pack for the router, that made no difference. I don't put the phone line through the UPS, only the power for the router is connected. Also, the UPS circuitry is not helping in keeping it stable, I have to actually turn off the UPS, i.e. the router is running off the batteries, only then does the ADSL line sync again. I have also looked at the stats for the router, can't be that cause my average downstream noise margin is 35dB (sometimes it dips to about 25dB, but only momemtarily). So you see why I can't pinpoint the problem? Doesn't make sense to me. I'll try some of the scenarios you suggested but recently everything seems to be fine, so it's going to be difficult to test. I suspect in winter it'll be a problem again.
 
@qinglung: What type of router are you using? Is your router now working correctly off both mains power as well as the UPS or only off the UPS? Is this only a problem in winter?

Just to repeat the obvious, are you quite sure that you have eliminated the possibility of faulty mains (wiring, adapters, sockets, extensions, switches) or faulty lightning protection, microfilters, telephone (sockets, extensions, cables, RJ11 connectors) etc.?

I think that it might be a good idea to monitor the fluctuations in your downstream noise margin using routerstats *both with and without the UPS* as a sudden drop of 10dB would seem a bit unusual. Could the router be dropping out due to these sudden 10dB drops even though the noise margin may never dip below 25dB? Apparently the TI AR7 router chipset (used in the Telkom Mega 100WR etc.) does not perform very well when the noise margin fluctuates wildly.

Have you actually tested the router on/at a different line/location just to be quite sure that it *can* work correctly off normal mains power and not just off the UPS? I assume that the UPS is also supplying 220~240V from the internal battery to power the router's external power pack or are you running the router directly from the UPS battery i.e. without the external power pack?

Do you have any problems using a PC without a UPS such as frequent reboots due to power spikes or surges etc?
 
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Yotch said:
What type of router are you using? Is your router now working correctly off both mains power as well as the UPS or only off the UPS? Is this only a problem in winter?
Click to expand...

The router is a Microcom, I think using a Conexant chipset. It mostly works fine off mains power, except when there are other heavy loads on, then it struggles to sync, when I put it on UPS batteries it immediately syncs again. During winter it was a major problem cause then lots of heaters were on in the house. First time we noticed it was when a certain heater was turned on and you see the line drop, switch off the heater and it syncs again. I thought it might be that specific heater, but it turned out not to be. Now in summer it only happens occasionally, normally when the stove is turned on.

Yotch said:
Just to repeat the obvious, are you quite sure that you have eliminated the possibility of faulty mains (wiring, adapters, sockets, extensions, switches) or faulty lightning protection, microfilters, telephone (sockets, extensions, cables, RJ11 connectors) etc.?
Click to expand...

I tried plugging the router power pack into an entirely different circuit, thought that the one I'm using might be overloaded, no effect. Tried with telephone and fax removed, made no difference. Tried another power pack, no difference.

Yotch said:
I think that it might be a good idea to monitor the fluctuations in your downstream noise margin using routerstats *both with and without the UPS* as a sudden drop of 10dB would seem a bit unusual. Could the router be dropping out due to these sudden 10dB drops even though the noise margin may never dip below 25dB? Apparently the TI AR7 router chipset (used in the Telkom Mega 100WR etc.) does not perform very well when the noise margin fluctuates wildly.
Click to expand...

Few months back I've had Routerstats running over an extended period of time, I saw the 10dB drops but the router was still syncing fine. Before sync loss, noise margin would be stable and then suddenly sync loss, when something was turned on, no major fluctuations before the loss.

Yotch said:
Have you actually tested the router on/at a different line/location just to be quite sure that it *can* work correctly off normal mains power and not just off the UPS? I assume that the UPS is also supplying 220~240V from the internal battery to power the router's external power pack or are you running the router directly from the UPS battery i.e. without the external power pack?
Click to expand...

As I stated above, it mostly works fine off mains power and when we had the difficulties in winter, we also tried it on a different circuit, no change. Yes, I'm using the 220~240V supply from the UPS.

Yotch said:
Do you have any problems using a PC without a UPS such as frequent reboots due to power spikes or surges etc?
Click to expand...

PCs are all running fine, none of them on a UPS. The UPS was specifically obtained for this problematic router.
 
@qinglung: Other people have also reported similar mains interference problems and are currently running their routers off a UPS. There must surely be a simple way though to power it off the mains. Here are a few ideas regarding mains RFI/EMI filters.

Some RFI/EMI problems can be eliminated by twisting the lead from the power pack around a toroid core. See below.
http://www.ky-filters.com/ac.htm
(FT240-43 toroid core Outer Diameter 2.4 Height 0.5 Al Value 1075 Inner Diameter 1.4 inches?)

Mantech seems to stock several toroids that should be suitable. Just phone first to confirm the size and price. You could look at say the 14M5515, 14M5521, 14M5563 etc. The size of the actual toroid isn't that important as long as it can hold enough turns (20~25). You could reduce the thickness of the power cable and use a smaller, cheaper toroid etc.
http://www.mantech.co.za/Stock.aspx?Query=ARNOLDand

Another option is to purchase an integrated mains RFI/EMI filter module such as this http://www.sidewindercomputers.com/ty10corfifi.html
Spectron (www.spectron.co.za) seem to have three pages of different types on their website for example. A 1A filter should be more than adequate. Mantech also has a few.
http://www.spectron.co.za (look under Accessories EMI filters).

You could purchase a prewound filter from Mantech (search for toroids, EMI filters etc.) or Supprescraft (www.supprescraft.co.za) and solder it into either the mains power lead or the one leading to the router.

You could look at off the shelf RFI/EMI filters from Supprescraft, Clearline etc. but these would be considerably more expensive - nearly as much as a UPS. Maybe you could borrow one first to test before purchasing something that might not help.

If the router runs off a 12V supply you could temporarily try to power if directly from a hard drive power connector in your PC to see if this makes a difference - just be very careful with the polarity or you could damage the router.

If you have any success with solving this problem please post your feedback as this could help other people who have been having similar problems.
 
Last few posts derailed this thread a bit ;), but just a quick update of my situation in case it might help someone else.

Last few days things got worse again with modem losing sync constantly. Tried some of Yotch's suggestions, nothing helped. I also tried 2 different transformers after realising the previous ones I tried were switching transformers, which apparently can make things worse for modems. That helped a little bit but in the end didn't solve the problem.

I finally got fed up with the Microcom modem (almost put a fist through it yesterday :mad:) and bought a new Billion modem today. Surprise, surprise! So far it seems rock solid, been up for the last few hours (touches wood :D).

Interestingly, the noise margins reported by the Billion is quite different. The Microcom showed on average 35dB with dips to 25dB every now and then. The Billion shows an almost constant 25dB, varying by about 2dB now and then. There are times it would be a bit higher or lower, but then it stays constant at that level, not such variance as with the Microcom.
 
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