dslreports logo
site
 
    All Forums Hot Topics Gallery
spc

spacer




how-to block ads


Search Topic:
uniqs
2016
share rss forum feed

bryant313

join:2011-05-24
Las Vegas, NV

[NV] Heat Throwing Off Modem Signal Levels?

for the past week or so i have noticed signal fluctuations on the upstream power level usually my upstream power level sits around anywhere between 39dBmv to about 42dBmv

well in the last week my upstream power level has jumped up to about 56.2dBmv the highest i have ever seen it

now i have heard about heat making the signals fluctuate
but by this much?

also would like to note that my downstream power levels have remained the same through these spikes/jumps

i have a DPQ3212 modem



BillRoland
Premium
join:2001-01-21
Ocala, FL
kudos:3

I've seen this happen before and the culprit was a bad line amp somewhere down the line. Not saying that's the case in this instance but it can wreak havoc.


bryant313

join:2011-05-24
Las Vegas, NV

interesting maybe i will call in then see if i could a supervisor out to take a look at it

i failed to mention this happened a few weeks back as well

and one more thing no cables or splitters or anything on my end has changed since this started occurring all the cables are new and all the equipment is new

and in past years i have never saw this type of issue before


Beezel

join:2008-12-15
Las Vegas, NV
reply to bryant313

I haven't had any fluctuations on mine here. So it must be something near you.


bryant313

join:2011-05-24
Las Vegas, NV

yeah i am on the phone with tech support and the guy is very knowledgeable and i will have someone out Tuesday to take a look at the issue

yeah he was telling me from comparing some of the different levels on the street that it is at the tap he said the tap itself could be bad or the ports are bad or something at the street is causing this issue

i have no time out errors i was told that i have a very clean signal so i can not be something in my house

and all the cable connections are tight and all the cables are new


lilstone87

join:2009-04-09
Portsmouth, VA
kudos:3
Reviews:
·Cox HSI

Well if there is big change in weather where it gets pretty hot outside, I could see maybe a 3-4db max increase on your upstream power. But the levels you are reporting is showing there is something acting up somewhere. Which could possibly be an amp acting up, as heat only causes issue's. Another reason more people see T3's/T4's in there modem log during the summer.



Irish Shark
Play Like A Champion Today
Premium,MVM
join:2000-07-29
Las Vegas, NV
kudos:5
reply to bryant313

It is the heat. The upstream can peg the top of the limits and you will drop offline.

It also matters if your fiber/coax is above or below ground.

Above ground will see more fluctuations. When I was in NY with OOL, all the fiber/coax was above ground. Hundreds of folks (me included) would see the meter peg to the limit and MODEMs dropped off line all over the place.

The temps in NY are not even close to what we see here in LV. I used to have the formula for every degree in temp how much the Upstream would move. I cannot find it; must have lost it in the move.

I am up in Summerlin and everything is below ground. Right now my Upstream is 42dBmV.
--
"You can observe a lot by watching". Yogi Berra


XIII

join:2010-06-16
Scottsdale, AZ
reply to bryant313

The amps are supposed to have regulation set, which helps it keep a somewhat stable signal levels when the temperature changes, though the regulators sometimes get removed when they are doing maintenance and all works fine without regulation until the temperature changes or they do something at another amp etc, lots of factors go into play as to what can cause the amp to have varying signal levels.
--
»FreeDNS.afraid.org - Free DNS dynamic DNS subdomain and domain hosting


bryant313

join:2011-05-24
Las Vegas, NV
reply to Irish Shark

thing is i never dropped offline while this was happening


bryant313

join:2011-05-24
Las Vegas, NV
reply to lilstone87

my thoughts exactly


bryant313

join:2011-05-24
Las Vegas, NV
reply to XIII

whatever it may be this is not the first time this has happened so hopefully the problem can get resolved


bryant313

join:2011-05-24
Las Vegas, NV
reply to lilstone87

now i am noticing lag when gaming and and some pages loading slower that usual


Beezel

join:2008-12-15
Las Vegas, NV
reply to bryant313

Yea Irish Shark everything is mostly below ground except in Henderson and the East end of the valley.



Irish Shark
Play Like A Champion Today
Premium,MVM
join:2000-07-29
Las Vegas, NV
kudos:5
reply to bryant313

said by bryant313:

whatever it may be this is not the first time this has happened so hopefully the problem can get resolved

Has this happened when it is 80 or lower outside? Or is this just happening during the precious weeks?

A MODEM is not a very scientific measurement tool. The readings can/are not exact.

According to the DOCSIS specs on Cable MODEM operational levels, the MODEM must work with a DS signal level of +8 to +58 dBmV. ISPs set the lower and upper limits on a much more conservative level.

So your reading of 56.2dBmV still has some room left before you start seeing the MODEM acting up.

Now you are reporting lags and slow page loads.

Do you have any critical errors in the MODEM log?
--
"You can observe a lot by watching". Yogi Berra

lilstone87

join:2009-04-09
Portsmouth, VA
kudos:3
Reviews:
·Cox HSI

Your right about modem isn't the best at judging signal levels, but if there is that much swing in power levels on a modem. Good chance it's a cable issue on down the line somewhere. Because if the modem is reporting that much of a swing in levels, it would point to a problem with the modem itself, if the modem was old. As for at 56db being room before the modem acts up, please look at the requirements of D3 modems, and the max levels when using a D3 modem. As I know with D3 modems bonding on the upstream the max is 51db, before the modem will have problems bonding on the upstream. Also I am sure even with a D2 modem max is probably only around 53-55db, and he's reporting power level swings up to 56db.

Anyways not to say a modem can't work at levels that high, just don't expect the performance to be good. Also with him complaining of lag now, its possible. As he's reporting big swings in upstream power levels. All I can suggest to him about lag problem, is start running steady traceroutes.


bryant313

join:2011-05-24
Las Vegas, NV
reply to Irish Shark

no errors in my modem logs the internet is running fine today i am still having a tech visit though


bryant313

join:2011-05-24
Las Vegas, NV
reply to lilstone87

well if its the modem this will be the 3rd modem swap in less than a year



Irish Shark
Play Like A Champion Today
Premium,MVM
join:2000-07-29
Las Vegas, NV
kudos:5
reply to lilstone87


Cisco Manual On This MODE>
I guess we all will see if the thing gets fixed. I have seen other folks with this same issue, but I never saw what fixed it.

Since you have this MODEM, you are more of an expert than me, since I not even sniffed this MODEM.

That Particular MODEM has various limits depending on the modulation and number of Upstream that are bonded.

I do not have the foggiest how his MODEM is connecting. However the manual from Cisco has the chart above.

The FAQ (»Cox HSI Forum FAQ »What should my modem signal levels be?) has this:

Upstream (Transmit): 40-52 dBmV. A value within the range +40 to +52 dBmV is within spec with the low to mid 40's the most common. If the cable modem is going offline, and the upstream signal strength is at or above +52dBmV, then a poor upstream path is probably the problem.

I think the levels in the 40's are what Cox wants to see on their network.
--
"You can observe a lot by watching". Yogi Berra

bryant313

join:2011-05-24
Las Vegas, NV

thank you for the info its much appreciated yeah i am curious myself what they will do if anything for this issue



news

@videotron.ca

Re: [NV] Heat Throwing Off Modem Signal Levelthe center s?

Temperature changes (high heat, very cold) will affect dwnstream signal but not upstream. Upstream variations means attenuation on low frequencies, caused by corossion, bad connector (partially short) or loose connector, cable squirrel chew, staple in cable, bad tap... Upstream isn't suppose to change much... An aluminium braid lost inside a brand newconnector touching the center pin can cause 10 dB upstream variation...


videonex

join:2001-07-22

said by news :

Temperature changes (high heat, very cold) will affect dwnstream signal but not upstream. Upstream variations means attenuation on low frequencies, caused by corossion, bad connector (partially short) or loose connector, cable squirrel chew, staple in cable, bad tap... Upstream isn't suppose to change much... An aluminium braid lost inside a brand newconnector touching the center pin can cause 10 dB upstream variation...

Extreme heat like they have had in Las Vegas recently will cause many of the very things you mention to happen. Your's is really the best explanation so far. I have found that corroded connections are usually the culprit. The metals expanding in the heat exaggerate the corrosion and line resistance in the upstream frequency range increases and in turn the modem ups it's output power to compensate.

I've found a shotgun approach by replacing any connectors, barrels and splitters located outside will usually cure the issue.

bryant313

join:2011-05-24
Las Vegas, NV

even with all the cable lines and splitters inside and outside the home being new?

less than a year


videonex

join:2001-07-22

Yes. Partially because it's quick and the least expensive but it's also the culprit much more often than not.

Hopefully your tech comes at the hottest part of the day. If he does the connection replacement first, the modem upstream power will show an immediate improvement if it has been solved.

If not then you move on to checking tap and lines. Connections on the tap are the next most likely culprits.


bryant313

join:2011-05-24
Las Vegas, NV

that is the thing it is not a consistent number it varies a lot and is very random at what times it happens whether it be day or night

and on days like yesterday it did not change much only plus or minus like .3dBmv which i would say is normal but on other days like Friday Saturday and Sunday where it change anywhere from 5dBmv to 15dBmv



Irish Shark
Play Like A Champion Today
Premium,MVM
join:2000-07-29
Las Vegas, NV
kudos:5
reply to news

One word: Wrong


bryant313

join:2011-05-24
Las Vegas, NV

cox tech came out today and the signals were spiked while he was here the modem and the hd boxes were all failing

so he plug every cable into his meter and tested every line in the home and at the street including the tap and there was no interference

and he saw that the neighbors signal was flucuating just like mine so he turned it over to maitence and we will see what happens tomorrow


XIII

join:2010-06-16
Scottsdale, AZ
reply to bryant313

Re: [NV] Heat Throwing Off Modem Signal Levels?

If you still have issues Thursday, call and ask for a supervisor to come out and check, they can get maintenance there the same day.
--
»FreeDNS.afraid.org - Free DNS dynamic DNS subdomain and domain hosting


bryant313

join:2011-05-24
Las Vegas, NV

1 edit


EDIT they did in fact come out they changed the face plate at the tap so hopefully this is the end of the spiking signals


videonex

join:2001-07-22
reply to bryant313

BINGO! That was my second solution, which effectively replaces the tap connectors. You are probably good now but keep us informed if the problems persist.



dsttechs

@wideopenwest.com
reply to Irish Shark

Re: [NV] Heat Throwing Off Modem Signal Levelthe center s?

2 words: 100% correct

As in, News is 100% correct

Attenuation due to heat affects the higher downstream frequencies, not the lower upstream frequencies. Since the modems downstream levels were unaffected that rules out attenuation due to heat. Because this modem keeps turning up its transmit it sounds like it was trying to overcome some sort of unwanted noise.

Keep an eye on your upstream SNR (signal to noise ratio), if the problem persists let the tech know what its doing in relation to the upstream levels. If it is a noise issue in the plant it's probably affecting many modems and maintenance is probably already aware there is an issue.