 train_wreckslow this bird down
join:2013-10-04
Antioch, TN
Cisco DPC3939
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[Signals] DS power levels rise +4dbmv during cold weatherour typical levels are around 3-4 dbmv (what they were yesterday), but today we're having semi-freak snow & sub-20 degree weather. Now they've shot up to 7-8. Could this be related to cold weather, and is there anything to be done? I've noticed our download speeds are dipping down into the ~90mbps range today, when it's normally ~105. SNR's seem solid (3 of them are identical) |
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Yes, I had found that my downstream levels would rise by up to 8 dB during a near-zero cold spell back in early January. See this previous thread about this: » [Connectivity] I hate cold weather |
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 MDAAuto Negotiating
Premium Member
join:2013-09-10
Minneapolis, MN
Asus RT-AC66U B1
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to train_wreck
Bah, At least you guys don't reside in Minnesnowta. It's fun watching the modem's downstream level's go up to 13+ on a -20 night.
I hope I don't have replace the outside splitters in the box on my house after it warms up. This year's weather is the worst cold I've seen since '91. |
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train_wreckslow this bird down
join:2013-10-04
Antioch, TN |
that sounds like real fun lol.
i'm guessing you can daisy chain splitters, e.g. to further decrease the power levels? if so i might do that here, just to get our average levels down to 0-1 and peak levels would be around 5-6 |
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 EGThe wings of love
Premium Member
join:2006-11-18
Union, NJ |
EG
Premium Member
2014-Mar-4 3:34 pm
said by train_wreck:i'm guessing you can daisy chain splitters, e.g. to further decrease the power levels? if so i might do that here, just to get our average levels down to 0-1 and peak levels would be around 5-6 Just bear in mind what all that extra attenuation does to the upstream / return power level(s). Don't want to throw them out of spec trying to fix the forward / downstream. It's always a balancing act when *overall* attenuation is employed. |
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train_wreckslow this bird down
join:2013-10-04
Antioch, TN Cisco ASA 5506
Cisco DPC3939
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said by EG:Just bear in mind what all that extra attenuation does to the upstream / return power level(s). Don't want to throw them out of spec trying to fix the forward / downstream. It's always a balancing act when *overall* attenuation is employed. cool. it appears our upstream has a fair amount of breathing room, so i might try it & see what happens. |
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EGThe wings of love
Premium Member
join:2006-11-18
Union, NJ |
EG
Premium Member
2014-Mar-4 3:56 pm
Yes it does. Try to keep it below 50 dB. |
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Thordrune
Premium Member
join:2005-08-03
Lakeport, CA |
to train_wreck
You can, although make sure to terminate the unused ports. Another option is to buy a 3 or 6 dB pad, or ask a nearby tech for one. I wish my speeds were dropping by that much. In the morning, I get 86 Mbps flat. Right now, I'm lucky to average 30  . |
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train_wreckslow this bird down
join:2013-10-04
Antioch, TN Cisco ASA 5506
Cisco DPC3939
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it worked |
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Matt7
join:2001-01-02
Columbus, OH |
to train_wreck
This is normal... Signal levels fluctuate a few db depending on the weather... I know when we had the -41F wind chills I was seeing -5 dbmv while normal conditions 40F + I see -7 to -9 dbmv)
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to train_wreck
I've experienced what you see with your signal strength. During the summer months, here in Tennessee, it can get into the 90's and 100's, and during the winter can get sub zero. During the winter months signal strength will run +-0db to +5db whilst during the summer months it will run -15db to -20db. What I do is to connect a signal amplifier during the summer to boost this signal, and take it off during the fall and winter months so it doesn't run too strong.
I figure, somewhere there's a amplifier that needs to be replaced. As amplifiers get older they become more susceptible to the temperatures (less efficient the hotter they become), and the output suffers because of it. It's been like that in my area for a couple of years, and I called Comcast about it. The answer I go was that if the tech didn't find any problems they would charge me 120 bucks (there abouts). So rather than face a possible charge, I just implemented my own fix.
I don't need the cable amplifier anymore, so let me know if you're interested in purchasing it.
David |
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 camperjust visiting this planet
Premium Member
join:2010-03-21
Bethel, CT |
to Matt7
said by Matt7:This is normal... Signal levels fluctuate a few db depending on the weather... In my instance, I suspect there is something besides weather that affects signal levels. I wrote a script that captures the signal levels every five minutes. In the following, the columns are: date, time, downstream s/n for four channels, downstream power levels for four channels, upstream power levels for two channels.
03/01/14 10:48:06 36 36 36 36 4 5 5 4 48 47
03/01/14 11:03:12 36 36 36 36 4 5 4 3 48 47
03/01/14 11:18:14 36 36 35 35 3 3 2 0 48 47
03/01/14 11:31:45 36 36 35 35 2 4 0 0 48 47
03/01/14 11:48:20 36 35 34 34 3 0 -4 -2 48 47
03/01/14 12:02:16 35 34 33 33 -2 -5 -9 -5 48 47
03/01/14 12:17:01 35 34 33 33 -3 -7 -10 -5 48 47
03/01/14 12:33:21 35 34 33 33 -3 -7 -10 -5 48 47
03/01/14 12:48:24 35 34 33 33 -3 -7 -10 -6 48 47
03/01/14 13:03:19 35 34 33 33 -4 -7 -11 -6 48 47
03/01/14 13:17:54 35 34 33 33 -3 -6 -11 -6 48 47
[...]
03/01/14 23:47:48 35 34 33 33 -3 -7 -10 -4 48 47
03/02/14 00:02:30 35 34 33 33 -3 -6 -10 -5 48 47
03/02/14 00:16:49 35 34 33 33 -3 -6 -9 -4 48 47
03/02/14 00:33:30 35 35 34 33 -1 -4 -8 -3 48 47
03/02/14 00:48:07 36 35 34 34 0 -2 -6 -2 48 47
03/02/14 01:03:19 36 35 35 34 5 1 -2 0 48 47
03/02/14 01:18:27 36 36 35 35 4 3 0 0 48 47
03/02/14 01:32:43 36 36 35 35 3 4 1 0 48 47
03/02/14 01:47:46 36 36 35 36 4 5 4 2 48 47
03/02/14 02:02:54 36 36 36 36 4 6 5 3 48 47
03/02/14 02:18:12 36 36 36 36 5 5 6 5 48 47
03/02/14 02:32:32 36 36 36 36 6 6 6 6 48 47
I see those sort of signal level swings regardless of what the weather is doing. |
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Yeah, those are some big fluctuation  I've seen fluctuations of +-2db over 8 hour day, but you are showing large fluctuations over an hours time. Looks like it's fading in and out. When the script is running and you see these low levels, have you doe any network troubleshooting like a continuous ping to see if it's affecting network performance? David |
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camperjust visiting this planet
Premium Member
join:2010-03-21
Bethel, CT |
camper
Premium Member
2014-Mar-5 11:59 am
I ping a server every minute (single ping with a 1 second timeout). No problems there at all. Indeed, I was so surprised at the lack of issues that I ran tcpdump for a while to make sure the ping was working. It was. |
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A ping once a minute may not be a good enough indicator. Try a continuous ping (1 a second).
Or just do the continuous ping when you know levels are low.
Use the -t option |
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camperjust visiting this planet
Premium Member
join:2010-03-21
Bethel, CT |
camper
Premium Member
2014-Mar-5 2:04 pm
said by davidc502:Or just do the continuous ping when you know levels are low. I'd probably do that option. I originally set up the ping script to let me know when connectivity was lost for minutes at a time (e.g., early morning maintenance by Comcast). But the script is flexible, and I can easily bring it down to a one ping per second when I see the low levels. Of course, I could have the ping script read the data from the check-levels script and adjust the ping timing automagically when the levels are low.  |
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to camper
Would you mind sharing your script. I would love to get something like that but my attempts aren't going that well. |
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camperjust visiting this planet
Premium Member
join:2010-03-21
Bethel, CT |
camper
Premium Member
2014-Mar-5 2:39 pm
Provided with no support. I wrote it, and it runs, on FreeBSD 10.0. I run it via an every-five-minute cron job. Oh yeah, it is probably very specific to the modem model I have: Model Name: SB6120 Vendor Name: Motorola Firmware Name: SB_KOMODO-1.0.6.10-SCM00-NOSH Boot Version: PSPU-Boot 1.0.0.4m1 Hardware Version: 3.0 Firmware Build Time: Oct 29 2012 18:07:13 |
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Well done on the shell script. I looked over it, and it must have taken you some time to develop.
Bottom line is that it's something that works for you, and is especially helpful during times like these. |
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camperjust visiting this planet
Premium Member
join:2010-03-21
Bethel, CT |
camper
Premium Member
2014-Mar-5 3:03 pm
said by davidc502:it must have taken you some time to develop. A couple of hours and a bottle of Brooklyn Brewery's Black Chocolate Stout. |
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train_wreckslow this bird down
join:2013-10-04
Antioch, TN Cisco ASA 5506
Cisco DPC3939
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said by camper:
A couple of hours and a bottle of Brooklyn Brewery's Black Chocolate Stout. :) a lovely beer to accompany code monkeying :) and i like your sed/awk chaining, done a bit of that myself in my podcast downloader script .
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URLSTRING=`echo "$b" | awk "$AWKSTR" | grep $GREPSTR | sed 's/"//g' | sed 's/ //g'`
TITLESTRING=`echo "$b" | awk "$TITLEAWK" | sed 's/:/ -/g;s/*/ /g;s/\///g;s/"//g;s/<//g;s/?//g;s/|//g'`
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camperjust visiting this planet
Premium Member
join:2010-03-21
Bethel, CT |
camper
Premium Member
2014-Mar-5 4:41 pm
Yeah, I do the script coding to relax at the end of the day.
The sed chaining just strips away the html stuff bit by bit, and awk builds up the csv line.
Not the prettiest code, but it has been working well. |
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 K3SGM- -... ...- -
Premium Member
join:2006-01-17
Columbia, PA |
K3SGM to MDA
Premium Member
2014-Mar-5 6:23 pm
to MDA
said by MDA:Bah, At least you guys don't reside in Minnesnowta. It's fun watching the modem's downstream level's go up to 13+ on a -20 night.
I hope I don't have replace the outside splitters in the box on my house after it warms up. This year's weather is the worst cold I've seen since '91. You might want to check those outdoor splitters when it gets warmer, the epoxy backed ones collect water, and will cause those kind of signal variations due to extreme temperature. As to the OP, my downstream level usually sits at +8dB in cold weather, and drops to around +5dB when it warms up, maybe +1 or +2 dB on a 100 degree day. Never had any modem issues with it changing like that, and since I buried the drop myself, it's down 12-24 inches in conduit, and not likely bothered by weather. The effect is probably much more of Comcast's plant warming and cooling than the drop itself. I could get picky and add/remove attenuators all year long, but if it isn't causing any problems to begin with......If it ain't broke, don't fix it. |
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train_wreckslow this bird down
join:2013-10-04
Antioch, TN Cisco ASA 5506
Cisco DPC3939
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said by K3SGM:As to the OP, my downstream level usually sits at +8dB in cold weather, and drops to around +5dB when it warms up, maybe +1 or +2 dB on a 100 degree day.
Never had any modem issues with it changing like that, and since I buried the drop myself, it's down 12-24 inches in conduit, and not likely bothered by weather.
The effect is probably much more of Comcast's plant warming and cooling than the drop itself.
I could get picky and add/remove attenuators all year long, but if it isn't causing any problems to begin with......If it ain't broke, don't fix it. that's actually another thing i've wondered, does it matter if a splitter is indoors/outdoors? i've got 1 in the ground box and another inside atm |
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K3SGM- -... ...- -
Premium Member
join:2006-01-17
Columbia, PA |
K3SGM
Premium Member
2014-Mar-5 6:38 pm
It's a problem if the splitter is outdoors and the back is epoxied on, because they aren't sealed properly(gets worse with age) and they soak up water like a sponge.
The soldered ones are usually OK for outdoors as long as the F connectors are tight, and don't allow water past them.
Outdoors also has the problem with the loose F connectors, because water gets into them too, which then turns to ice, which loosens them even further. |
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train_wreckslow this bird down
join:2013-10-04
Antioch, TN Cisco ASA 5506
Cisco DPC3939
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word. related to this issue, is there any difference between using a splitter and an attenuator (like this » www.amazon.com/gp/produc ··· 507846)? |
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K3SGM- -... ...- -
Premium Member
join:2006-01-17
Columbia, PA |
K3SGM
Premium Member
2014-Mar-6 5:23 am
An attenuator would have less insertion loss, or at least a loss that is more predictable.
Note that your attenuator screws directly onto the modem, where a splitter needs another short piece of coax to make the connection.
Fixed value Attenuators don't have internal transformers, which can magnetically saturate, due to stronger signal levels, and mess up your SNR readings.
I usually keep a handful of 1dB and 3dB attenuators around, just for making slight adjustments to signal strength when troubleshooting problems |
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 ·Carolina Mountai..
Synology RT2600ac
Linksys E2000
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to train_wreck
From info told to me during the long term Cable issue, I learned that each amp on the feed from optical to our house has a plug in board that is a temperature controlled AGC, and as happened in my instance multiple units in the 4 from optical to my house had these boards fail, and gain changes then happened "often"..... and since there were 4 amps in series..... Much diagnostic "Fun" was had by Comcast. Add to this a tap doing strange reflections a few poles upstream of my house, and the combinations of symptoms caused people to think that once they found one thing bad, and fixed it.... and there were multiple things bad in series.......
It took a while to fix..... Support over the phone would adjust gain to box, then temp change would happen, or amp drift, and I'd call again, and again...
Eventually Comcast replaced all wiring between Pole and TV's in house (no change) and then all 4 amps and one tap between me and Comcast optical feed was changed..... before things stabilized.... |
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EGThe wings of love
Premium Member
join:2006-11-18
Union, NJ
1 recommendation |
EG to K3SGM
Premium Member
2014-Mar-6 12:53 pm
to K3SGM
said by K3SGM:An attenuator would have less insertion loss, or at least a loss that is more predictable.
Note that your attenuator screws directly onto the modem, where a splitter needs another short piece of coax to make the connection.
Fixed value Attenuators don't have internal transformers, which can magnetically saturate, due to stronger signal levels, and mess up your SNR readings.
I usually keep a handful of 1dB and 3dB attenuators around, just for making slight adjustments to signal strength when troubleshooting problems Just wanted to add that you don't have to worry about capping any possible unused ports with an attenuator. |
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train_wreckslow this bird down
join:2013-10-04
Antioch, TN |
thanks all, gonna check if radio shack has any of these |
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