dslreports logo
site
 
    All Forums Hot Topics Gallery
spc

spacer




how-to block ads


Search Topic:
uniqs
3509
share rss forum feed

[TWC] cable modem snr values

Guys,

just upgraded to the TimeWarner 50/5 service and installed a Motorola SBG6580 docsis 3 modem. Running the speed test I am seeing a consistent 30/5 scenario rather than 50/5. The level 3 tech support person claims I am setup for 50/5 and that my line might be the issue.

Looking at the modem diagnostics I see the downstream power is 6.0 to 7dBmv and the SNR is around 42db. The tech support lady mentioned that the SNR looked high and has a technician coming out tomorrow to look at the lines.

Question I have is, isn't 42db good? I read the SNR should be 30 or higher. What should the values be? What are others with 50/5 service speed seeing?


SHoTTa35

@optonline.net
SNR of 42dB is sweet, prolly wont get much better than that in the real world.

How are you connected to the modem however, wireless? wired? I see you are using the Motorola gateway which has both that's why I ask.


news

@videotron.ca
reply to sandieg91218
In fact, for the SNR (signal to noise ratio), the higher the better. But there is one thing... If in a cable system you are use to see only 34 to 38 dB of SNR and one day you have a cable modem with high downstream power and 42 dB SNR you're not use to see, maybe it's a sign there is a line distribution amplifier with a too hot output power and the SNR is at the upper edge just before dropping down drastically. When a temperature drop happen, downstream power can rise and SNR can fall to 32 dB or less, eventually causing issue.

But it's all depend of the cable system. Here, 40 dB or higher SNR is unusual, maybe it's current in your system.


Bucolic

@swbell.net
reply to sandieg91218
Hi:
I'd like to ask about my signal levels as well. Apparently from the best I can tell in other threads, they are probably within limits, although I'm wondering if the upstream seems to be a tad lower than what is usually considered optimal, or is all the following acceptable:

Upstream +31.9 dBmV
Downstream +1.1 dBmV
SNR 35.4

Thanks.


motorola870

join:2008-12-07
Arlington, TX
kudos:4
said by Bucolic :

Hi:
I'd like to ask about my signal levels as well. Apparently from the best I can tell in other threads, they are probably within limits, although I'm wondering if the upstream seems to be a tad lower than what is usually considered optimal, or is all the following acceptable:

Upstream +31.9 dBmV
Downstream +1.1 dBmV
SNR 35.4

Thanks.

my upstream has in been in the 30dBmv range for over a month it goes from about 32dBmv to 30dBmv throughout the day. An optimal upstream is 40dBmv to 49dBmv power level.


CptGemini
Inside your computer
Premium
join:2004-11-29
Corpus Christi, TX
kudos:6
reply to sandieg91218
If they claim you are set for 50/5 but still get 30/5 they may be lieing. On the ubees you can go under operation config and see what you are provisioned for, I don't know about the moto one though so someone else would have to chime in on where if it is even possible to see that kinda information. I took a couple of clips from my modems operation config page to kinda show you what I was talking about. Take note of the numbers next to max traffic rate.
--
»www.akaskriller.com - Your ultimate source for all android needs.


news

@videotron.ca
reply to motorola870
In cable, nothing is perfect. If you have a low upstream, your cable modem transmit near the noise level. If there is high noise, ingress issue on your node, modems with low upstream power will have to do more data correction to correct errors caused by noise. It will be easier for data to pass through the noise with modems with a higher upstream power (higher upstream signal-to-noise ratio).

But, if there's a upstream power variation issue caused by the cable plant or your cable installation, 10 dB or more upstream variation can cause cable modems with normally 45 dB upstream power to rise to 55 or higher level and cause loss of connection, no Internet at all.

Modems with low upstream power won't disconnect with the same 10 dB upstream rise.

Modems connected to a end of line will get lower upstream power caused by little attenuation of lower tap value. Modems connected near a node or distribution amplifier, at the head of a cable line will get higher upstream power caused by more attenuation from higher tap values.