High power levels?

[Dawn Falcon]

Hi all;

One of my connections is a VM 20Mbit and I've been seeing erratic ping times recently, and looking at the guide above on power levels, my downstream power level seems high.

Downstream Lock : Locked
Downstream Channel Id : 0
Downstream Frequency : 402750000 Hz
Downstream Modulation : QAM256
Downstream Symbol Rate : 5360.537 Ksym/sec
Downstream Interleave Depth : taps32Increment4
Downstream Receive Power Level : 17.1 dBmV
Downstream SNR : 43.7 dB

Is this sufficient to call VM (ofc on Monday!) and raise a ticket? Is this a fix at their end, a modem replacement or something else?


(upstream looks fine:

Upstream Lock : Locked
Upstream Channel ID : 4
Upstream Frequency : 29200000 Hz
Upstream Modulation : QPSK
Upstream Symbol Rate : 2560 Ksym/sec
Upstream transmit Power Level : 34.8 dBmV
Upstream Mini-Slot Size : 2

)

[darren.b]

Downstream Receive Power Level : 17.1 dBmV
Too high! Needs a tech out.

[Sephiroth]

For all the stuff I know about networks, there are mysteries involved with HFC networks that simply don't occur in my side of the networking business.

So far as I know, the CMTS would punt out at c. 40 dBmv power just like we expect the cable modem to do on its upstream. By the time the signal reaches your cable modem, all the impedances in between are supposed to bring the power down to a suitable level in milliwatts at 0 dBmv within the tolerances permitted by DOCSIS and having regard for the SNR.

When we see negative dBmv values, it could mean that there's too much impedance in the way, but if the SNR is good, it often means a modem that has drifted out of spec.

When we see out of spec high dBmv values, I really don't know what to make of it. is there a street amplifier gone crazy? Is there an aberration in the modem (unlikely IMO)? Why des the engineer merely fit a forward path attenuator when the root cause isn't established?

There are real branios around who know this stuff and I'd like to be educated (along with everyone else)!

[Peter_]

You need to call Tech Support which is open 24/7 even on Christmas Day on 151 from your Virgin Media Phone.

It's absolutely free.

Or call 0845 454 1111 from any other phone line.

You without doubt need a engineer to adjust that for you.

[Dawn Falcon]

Okay.

Well, when I try and call tech support it drops the call rather than transferring me to someone (not to mention that there's no suitable option, I have an issue with broadband which doesn't actually involve disconnection). Please hold *click*. Solution?

(And no, we don't have a VM phone, using skype which is fine on everything else. Heck, the system whines enough that I don't have a VM phone number at the start...)

Looked for a website login for a trouble ticket system and...er...it insists on wanting an email address which I've never set up. Nice. (Got an external email which works for the billing system...)


Actually, I've found something which was plugged into the previous VM modem we had (when someone else had the connection), it's A "Foward Path Attenuator" 15dB.

[Sephiroth]

Bungit on. It should lower your downstream power to a sensible level. Seems like there's an amplifier in your area doing something wrong. Or something like that.

Of course you do all this at your own risk.

[Dawn Falcon]

Yea I'm strongly inclined to do that and see if it sorts the issue out thanks to VM system phone system dropping my calls.

(I bet if I waited until monday, went for the disconnections team on the phone and said I wanted to speak to a tech that'd work, but meh if this attenuator will sort it, honestly...)

[Sephiroth]

If it doesn't do the trick, perhaps you could knock on a couple of doors and ask other VM users what's happening there. Even stats if they've got problems and you can be arsed!

Then there's a trail in this forum for VM's people to see.