Are my VM signal levels right?

[nibblitz]

Having some occasional issues with my VM Superhub.. Can anybody tell if my Signal Levels are ok, or do they look a little strong & would I benefit from fitting an attenuator?

They are:
Upstream Power: 51.4 dBmV
Downstream Power: -3.3 dBmV
Downstream SNR: 41.5 dB

Thanks for any help...

[jet]

New firmware should be out next week for superhub that fixes most issues.
Your upstream is a little high.

From Sephiroth:
"DOWNSTREAM POWER (Optimal)

Rule of thumb: -3 dBmv to +6 dBmv

The above advice compares with the VM stated optimum values by region (according to implemented infrastructure standards) and modulation:
QAM64 (Knowsley networks) -7 dBmv to +3 dBmv
QAM64 (Langley/Bromley) -10 dBmv to 0 dBmv
QAM256 -3 dBmv to +7 dBmv

This is not cast in stone. A good modem (Cisco 2100 comes to mind) can handle nearer the DOCSIS spec if the level is steady and the experience good. If the experience is bad, then look for high downstream power, particularly above the 9 dBmv mark.


UPSTREAM POWER (Optimal)

35 dBmv to 50 dBmv

This compares with the VM stated optimum values:
40 dBmv to 50 dBmv"

[nibblitz]

Thanks for that. So ummm, if I did whack on an attenuator to bring the upstream power down a bit would that not then knock my downstream power outside optimum levels?

[G77]

your levels look ok. if they wern't, the eng would have sorted it if he fit a superhub. whats the problem with the hub?

[nibblitz]

Most of the time its great.. But every so often, maybe once a month or so, I get a period of a few hours where any intense activity on my network, like lots of connections, it seems to crash the superhub.. Normally this isnt an issue, but when it plays up its so annoying.. Last night, the superhub would stay up for a minute, then crash, no network... I dont even have to reboot it, it just seems to come alive again after a couple of minutes.. Obvioulsy if I reboot it it starts up again quicker.. Ive got all the Firewall and flood setting options switched off.. Today it seems to be ok... Unless Im just experiencing VM network issues, but I wanted to see if something might be wrong with my connection.. If you say the levels seem ok I'll leave it alone..
thanks..

[G77]

i've only just gone 50mb and naturally i've been testing it out, lots of sessions and plenty of bandwidth made mine fall over. even heavy internal traffic used to screw it up.

some pages on the webgui crashed it too.

check your firmware version. they're just about to release version 30 which should start to hit the hubs round about now. i've put mine through some traffic and its not crashed/rebooted once.

[G77]

version is this...

Software Version V5.5.2R30

[nibblitz]

Its still V5.5.2R26 on mine, its behaving itself so far this evening, just gave it a hammering as a test.. Like I said, it'll probably be fine for a few weeks before I again experience the nonsense like last night... But if the new firmware is addressing this sort of problem then look forward to it hitting my super hub..

Have you got it on yours, are you a beta tester for it?? Ive heard that its going to have some sort of "Modem Only" switch in the settings to make it easier for customers to use their own routers..

[G77]

yeah, i signed up to beta test it a week or two ago.

my main interest was the modem mode as frankly i've seen better functions on a torch and theres a lot missing. vpn for a start.

not got round to sorting the modem mode yet as i've not had time. but now i've already made done with the functions might end up leaving it.

i used to reserve bandwidth for a machine or two and cap the kids laptops but i recon with 50mb theres no need

[nibblitz]

Well thats good to know this new firmware is working good for you.. Just hope they Zap mine soon now.. Suppose I might need to power it on/off occasionally from now on if this new firmwares coming out anytime soon...