Forum Discussion
Replaced my modem again. Still don't know why I am getting these dynamic range window violation errors.
So far:
3 new modems
New router
New coax from demarc to modem
New splitter from cox
New drop from street to demarc
After 8 tech visits, everything looks "fine". My internet is have intermittent disconnects and am still getting dynamic range window violations which cause thousands of uncorrectables on my channels
Dynamic Range Window violations won't directly cause uncorrectable errors on your channels, but an overall problem might cause both DRW violations and uncorrectable errors. Uncorrectable errors are a downstream data transmission issue.
A dynamic range window violation is an upstream problem that happens when your modem sends a ranging request and then gets back a power level request for a channel is more than 12 dBmV above the lowest power level in the upstream channel set.
Basically, at least 2 times per minute, your modem asks the Cox system "how loudly should I transmit on each channel?" If Cox comes back with numbers like 45, 44, 43, 41 then that's all good. But if it comes back and asks for numbers like 38, 36, 52, 39 that would be a dynamic range window violation because the highest value (52) is more than 12 above the lowest value (36).
I've tried to get someone to give me more information but so far I've had to learn all of this on my own while trying to troubleshoot my own problems. I don't know how bad a DRW violation is overall but it does seem like upstream data like video calls will glitch momentarily when a DRW violation happens. I think the DRW violation itself is probably caused by a momentary spike of noise on one of the upstream channels. Like I said I don't know this for sure but this makes sense based on what I've been learning.
When my connection was working well I would get two or three DRW violations per week at most. Then when my connection started to go bad, I was getting up to 40 DRW violations per hour. Now I'm getting T3 timeouts which is a more serious type of upstream issue that causes a complete interruption of data for a short time.
No one has been able to provide any real information about how serious DRW violations are, but I think of them as an early warning of problems that are going to get worse later.
I'll also say that two of your channels are at the highest recommended power level for 4 bonded channels (51 dBmv). Even though that's technically within spec, it leaves no room for error. Any little thing is going to send the power level above the recommended range. It's hard to get techs to understand that because they only look at the raw number, but that high of an upstream power seems like a developing problem. Some techs will also quote the highest power for a single channel which is 61 dBmV but if you're only using one channel you aren't getting your full upload speed so for the real modern world 51 dBmV is the maximum.
- Peterockinit5 years agoNew Contributor III
Thank you for the reply and info. The upstream channel power levels were 38 before, I called Arris and they recommended 47-51 so the tech added attenuators to reach. It didn't matter, I got the DRW still.
I just assumed that the drw was causing the uncorrectables because everytime I checked my modem (hourly), I would see a new DRW error and more uncorrectables stacked up also.
A new issue has developed now. My modem login (192.168.100.1) keeps locking me out, site says location can't be reached. It happens daily. The only way I know how to bring it back is to power cycle my modem BUT this clears my logs and I can't see if I am getting DRW errors now. What the hell????
- Dave95 years agoContributor III
IMHO Arris is wrong about those levels. I know they designed the modem but I have to wonder who wrote that specification page. I think they messed up. The CMTS/CCAP will request whatever levels it needs from your modem to get a good signal. Nothing wrong with 38 dBmV upstream power. Can you remove the attenuator? If so I would do that and see if the problem gets better.