HiVolt
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join:2000-12-28
Toronto, ON
clubs:
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| SNR Drops at regular intervals
I have a backup line at work that's relatively crappy, 4032/800 fastpath, at 54dB Atten.
It's stable, the sync doesn't drop, but the SNR paints an odd picture. Every day, the SNR is fine around 7-8dB from about 7pm to 7am, but from 7am to 7pm it fluctuates wildly usually below 5dB, sometimes as low as 3-4dB. There is a POTS splitter on the line, and it's hooked up right at the demarc. There is only one other device on the line and that is a FAX machine, but I have unplugged it and the same thing happens...
I'm just wondering if anyone has any other suggestions on what could be causing these SNR fluctuations for half a day.
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Bicephale
join:2005-09-24
·TekSavvy Solutions..
| Ayoye!
Only a mere 268 CRC Errors/Day With an attenuation
of 54.5 dB and an SNR Margin of only 4 dB!!! What
kind of device is that, where do we purcharse it!?
I experience something similar but i've shown that
it was related with our kitchen's stove with this:
%20.PNG)
Tweaks, Bicephale, 2007-Sep-06
Put it on batteries, cut the power for a whole day
and see what happens! My graphic clearly resulted
from the fact that i turned up all the appliances at
the beginning of each hour for a short period, i'm
not sure how you'll handle your problem but once a
clue emerges you can try to link cause and effect.
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HiVolt
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join:2000-12-28
Toronto, ON
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| said by Bicephale  :Ayoye! Only a mere 268 CRC Errors/Day With an attenuation of 54.5 dB and an SNR Margin of only 4 dB!!! What kind of device is that, where do we purcharse it!? SRC="http://us.i1.yimg.com/us.yimg.com/i/mesg/emoticons7/26.gif"> LOL. It's a lowly Siemens SpeedStream 4200 D240 w/A8M firmware.
I'm surprised its holding sync at these low SNR's. I've seen it drop to 1-2's at times. But getting back to the electrical interference that you suggest... You see that's where it's a weird one here... We have big presses here, with electric motors that run on 3phase 600V. But the printing is mostly done on the night shift, and that's where the SNR is nice and steady! Most of the other equipment that uses heavy power is used at night as well, and during the day it's mostly idle... The demarc is nowhere near any electrical lines. The modem itself is on a UPS as well.
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HiVolt
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join:2000-12-28
Toronto, ON
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| reply to Bicephale
said by Bicephale :Ayoye! Only a mere 268 CRC Errors/Day With an attenuation of 54.5 dB and an SNR Margin of only 4 dB!!! What kind of device is that, where do we purcharse it!? LOL. It's a lowly Siemens SpeedStream 4200 D240 w/A8M firmware.
I'm surprised its holding sync at these low SNR's. I've seen it drop to 1-2's at times. But getting back to the electrical interference that you suggest... You see that's where it's a weird one here... We have big presses here, with electric motors that run on 3phase 600V. But the printing is mostly done on the night shift, and that's where the SNR is nice and steady! Most of the other equipment that uses heavy power is used at night as well, and during the day it's mostly idle... The demarc is nowhere near any electrical lines. The modem itself is on a UPS as well.
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HiVolt
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Toronto, ON
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1 edit | The first shot of DMT was from yesterday, today paints a similar picture, in fact it's like this pretty much every day.
7pm to 7am, nice steady SNR. Drops and fluctuates from 7am to 7pm. The RX errors are most significant during that timeframe as well.
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Bicephale
join:2005-09-24
·TekSavvy Solutions..
| Hi,
I think d_l likes his SS4100B for related reasons,
he seemed to have some field-expertise of electric
issues and might have useful comments to make. It
would please me to read what he has to say about a
topic which i find puzzling myself: i've observed
a strange MoDem behaviour myself lately but it's a
tough one you've got here! More help is required,
my situation is very similar and yet i'm still not
sure how 60 Hz AC noise can be such a nuisance!...
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HiVolt
Premium
join:2000-12-28
Toronto, ON
clubs: | I'll have to bring my ST516v6 and test it on the line over a few days and record the stats/error counts.
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Bicephale
join:2005-09-24
·TekSavvy Solutions..
| Hi,
One big problem with these SpeedTouch units is the
fact that they all seem to suffer from amnesia!...
Their counters are reset for all sorts of reasons,
from what i can tell. You may have better results
using SNMP tools but my efforts to launch a thread
over ready-made bootable CDs wasn't so conclusive.
'STMT' is supposed to generate an Error Rate curve
but i've never seen one because it doesn't work on
my PC. Maybe you'll be luckier? Have a nice day!
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HiVolt
Premium
join:2000-12-28
Toronto, ON
clubs:
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| Man, it's gotten bad lately. But still 100% stable with no loss of sync.. I really have no idea how this modem can hold at below 5dB SNR for this long, on a daily basis. It goes as low as 1.5-2.0dB.
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Bicephale
join:2005-09-24 | Friendly salutations, HiVolt,
This is what i should have put my money on!
Tell me it's on sale in a Montreal store!!!
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HiVolt
Premium
join:2000-12-28
Toronto, ON
clubs:
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1 edit | Hehe, i dunno where to get one in Montreal... I'm sure you can find one on eBay. It's a SS4200 D240, I can provide with the exact details on the modem sticker on monday if you wish.
I'm using firmware A8M I can provide it for you if you acquire this modem.
BTW, I still haven't been able to isolate the source of the interference. I tried a different AC adapter for the modem, and it didn't make a difference.
The only thing I can think of is that our building is right beside an auto-body shop, and they are open from 8am to 6pm, and during the day there is a very loud noise coming from the back of their building, where it is adjacent to ours, and the phone lines run thru there... It's some kind of fan, or compressor, or something... I'm wondering if the motor or the electric wiring of that device is creating this wave of huge interference during the day...
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Bicephale
join:2005-09-24
·TekSavvy Solutions..
| 
HiVolt - SNR Margins |
I'm becoming more curious each time but i realized
only ISPs are authorized to sell it and only a new
unit freshly shipped by the manufacturer would do;
perhaps i'll ask a company like VelCom about it...
Your theory makes sense but i'd like to understand
how it works and what's the cure! I've inclosed a
superposition of the SNR Margin curves you posted,
it's like someone flipped a switch and the periods
match so closely it can't be a simple coïncidence. |
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HiVolt
Premium
join:2000-12-28
Toronto, ON
clubs:
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| said by Bicephale :Hi HiVolt, I'm becoming more curious each time but i realized only ISPs are authorized to sell it and only a new unit freshly shipped by the manufacturer would do; perhaps i'll ask a company like VelCom about it... Unless you're picky about it being brand new, there's no reason why a used one with the proper firmware loaded won't do...
Your theory makes sense but i'd like to understand
how it works and what's the cure! I've inclosed a
superposition of the SNR Margin curves you posted,
it's like someone flipped a switch and the periods
match so closely it can't be a simple coïncidence.
I'm going to go over to the shop next door on Monday, and ask them if I could take a peek at the machine that makes all that noise, perhaps see if its electrical wires run close to the exterior wall. The buildings don't touch, there's maybe 1foot of space in between.
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HiVolt
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Toronto, ON
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| »search.ebay.ca/search/search.dll···tegory0=
A few entries priced reasonably...
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