Cable modem signal levels!
 

Any chance on an update to 'sticky' please.
Would be nice to get an update to prevent an unnecessary phone call to Virgin?
Currently seeing 53/54dbmv on upload signals, do I have cause for concern? [This is on a SH2ac]

Re: Cable modem signal levels!
 

Good point, they haven't been updated in a long while.

Also, yes, your US levels are too high and would need a tech out to fix it. Any fluctuations higher and you'll likely lose an US channel or the whole connection. What are you other power levels/Network Log looking like?

Re: Cable modem signal levels!
 

stream DS-1 DS-2 DS-3 DS-4 DS-5 DS-6 DS-7 DS-8 Frequency (Hz) 306750000 266750000 274750000 282750000 290750000 298750000 314750000 322750000 Lock Status(QAM Lock/FEC Sync/MPEG Lock) Locked Locked Locked Locked Locked Locked Locked Locked Channel ID 106 101 102 103 104 105 107 108 Modulation 256QAM 256QAM 256QAM 256QAM 256QAM 256QAM 256QAM 256QAM Symbol Rate (Msym/sec) 6.952000 6.952000 6.952000 6.952000 6.952000 6.952000 6.952000 6.952000 Interleave Depth I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17 Power Level (dBmV) 1.62 2.86 3.14 1.88 1.83 1.64 1.50 1.44 RxMER (dB) 36.17 37.09 37.09 36.61 36.84 36.84 36.39 36.17

Re: Cable modem signal levels!
 

DS looks fine. Anything untoward (T-3/4 errors especially) in the Network log?

Re: Cable modem signal levels!
 

Nothing found in the log, mind you I have rebooted and will check after tea.

Re: Cable modem signal levels!
 

You haven't actually posted your Upstream (53/54dBmv) is a tad heated for 16QAM and too hot for 64QAM(which I recall max's at 52.2dBmv) but rather depends on what other "line conditioners/HDU" (or Not) you have on your drop?
A more comprehensive explanation in the form of Dave's(Seph's) Prima can be found on the QuickStart forum of the VM Community forums. Haven't bothered to check the more simplified "dipstick" guides here for several years.... :(

Normally as general Rule-of-thumb we say 50dBmv to allow for diurnal drift/contingency irrespective of Modulation type (at least upto 64QAM but you won't see higher mods for a while yet.....).

hth

Re: Cable modem signal levels!
 

Depends how many upstream channels are locked.

52 dBmV max would be for 3 or 4 upstreams @ 16 QAM
Whereas 2 x 64 QAM's would max at 54 dBmV.

Remember, the figures we quote now are to allow room for future channel upgrades.

Re: Cable modem signal levels!
 

Upstream US-1 US-2 US-3 US-4 Channel Type 2.0 N/A N/A 2.0 Channel ID 4 N/A N/A 3 Frequency (Hz) 25800000 N/A N/A 32600000 Ranging Status Success Other Other Success Modulation 16QAM N/A N/A 16QAM Symbol Rate (Sym/sec) 5120000 N/A N/A 5120000 Mini-Slot Size 4 N/A N/A 4 Power Level (dBmV) 53.25 N/A N/A 51.25 T1 Timeouts 0 0 0 0 T2 Timeouts 0 0 0 0 T3 Timeouts 0 0 0 0 T4 Timeouts 0 0 0 0

Re: Cable modem signal levels!
 

As an update to my last posting.
Spoke to offshore regarding upload power levels, no concern till reaches 55db/mv?

Re: Cable modem signal levels!
 

There's your problem, you spoke to offshore.

I've had engineer visits to correct power levels similar to yours. Good thing too as usually power levels crept up soon after so I would've had problems if they were not corrected.

Either speak to UK tech on the phones or use the VM Community forums for help.

Re: Cable modem signal levels!
 

At 54 dBmv the modem has maxed out for 2 upstream channels. At that point a T4 event occurs and the modem resets. You clearly have an upstream impairment. If a neighbour has the same, then it's a common cause fault' if not then it's somewhere I your bit from the cabinet to your house.

Re: Cable modem signal levels!
 

I believe it's just me Seph, rebooted and upload signal leveled out at 49db/mv.
Currently showing 49.9 and 50 for the 2 channels available.

Re: Cable modem signal levels!
 

Given it's been three weeks since your last post (outside this run), presumably upstream is not now playing up. Right?

Re: Cable modem signal levels!
 

Currently stable Seph,bearing in mind I'm on the Sam Knows monitoring team.
Would you believe if I said that UDP rock bottom since 08.00 yesterday starting to climb this morning @10.00.
Upstream US-1 US-2 US-3 US-4 Channel Type 2.0 N/A N/A 2.0 Channel ID 2 N/A N/A 1 Frequency (Hz) 39400000 N/A N/A 46200000 Ranging Status Success Other Other Success Modulation 16QAM N/A N/A 16QAM Symbol Rate (Sym/sec) 5120000 N/A N/A 5120000 Mini-Slot Size 4 N/A N/A 4 Power Level (dBmV) 50.00 N/A N/A 49.50 T1 Timeouts 0 0 0 0 T2 Timeouts 0 0 0 0 T3 Timeouts 0 0 0 0 T4 Timeouts 0 0 0 0Certain offshore comments need amending, they say 45db/mv to 55db/mv on upload is o'k?

Re: Cable modem signal levels!
 

As I mentioned before, the max is 54 dBmv on upstream, then the modem resets. There is no lower limit - if the upstream works at, say 29 dBmv, then that's enough power for the VM to make sense of what it's receiving.