Signal Check

rogeruk · 13-03-2007, 00:21

On a 2mb..

Downstream Receive Power Level : -6.8 dBmV
Downstream SNR : 35.3 dB
Upstream transmit Power Level : 44.0 dBmV

These good?. Get connection drops quite a few times during the day.

**Paul** · 13-03-2007, 00:26

http://www.cableforum.co.uk/board/12...al-levels.html

rogeruk · 13-03-2007, 01:22

Well, what can i say.. thanks for finding me a sticky!!!, so imformative.

NOT. "anything between" doesnt really help does it.

**Paul** · 13-03-2007, 01:31

Sorry, I'll try not to be so helpful in future, as will most other members I expect.

**Hugh** · 13-03-2007, 09:23

Quote:

Originally Posted by rogeruk

On a 2mb..

Downstream Receive Power Level : -6.8 dBmV
Downstream SNR : 35.3 dB
Upstream transmit Power Level : 44.0 dBmV

These good?. Get connection drops quite a few times during the day.

Quote:

Originally Posted by rogeruk

Well, what can i say.. thanks for finding me a sticky!!!, so imformative.

NOT. "anything between" doesnt really help does it.

If you read the Sticky properly

, you would have seen at the bottom of the first post that your readings are just around the minimum -6dBmV and 33dB recommended, which may be an issue.
"the recommended power range is -6dBmV to +15dBmV with a recommended SNR of 33dB.

In addition to this, Telewest are using the 16QAM upstream modulation in some areas. This requires an upstream transmit power below +55dBmV".

smelly-finger · 14-03-2007, 01:38

Quote:

OK, so you've browsed to http://root:root@192.168.100.1 and gotten your signal levels... to save any posts asking if their levels are OK here's a quickie guide as to real world acceptable ranges, rather than those dictated by the specifications for DOCSIS and EuroDOCSIS.

Downstream Receive Power: Ideally +/- 3dBmV, cause for concern at around +/- 8dBmV, different modems handle the higher and lower levels differently however I'd expect to see service degredation at that point.

Downstream SNR: Minimums are 24.5dB on the Langley platform and 26dB on the Bromley platform. Again these aren't the minimums required to function but when you're down this low you're teetering on the brink of losing your service.

Upstream Transmit Power: Anything between 28dB and 53dB is fine. Up to 55dB is also fine so long as it's fairly stable. Above 55dB suggests issues. Depending on your modem connectivity is jeopardised when transmit power hits 58dBmV or in the case of Pace set tops 61dBmV.

Edit: 18/02/2006

Both Telewest and ntl are now using the more efficient, but demanding 256QAM modulation in some areas. This gives more bandwidth but required better networks. For this modulation the recommended power range is -6dBmV to +15dBmV with a recommended SNR of 33dB.

In addition to this, Telewest are using the 16QAM upstream modulation in some areas. This requires an upstream transmit power below +55dBmV.

I read that also but was still a bit confused as it was set values and as my settings didn't match the "recommended" SNR i was worried my SNR was bad perhaps a better way to list this would be to give ranges rather that just a value.

I'm on QAM256 and my SNR is between 40 and 41 which is above the "recommended" is that bad I can't tell from the sticky, does a higher value mean a stronger signal or more noise i couldn't tell.

All i want to point out is that not everybody is as tech savvy and when we see that our setting/readings aren't matching up to the recommended values we can worry. I've been having awful problems with disconnects over the past few weeks and thought that my values had some bearing on this.

These are mine

Downstream Receive Power Level : 0.7 dBmV
Downstream SNR : 41.2 dB

Quote:

recommended power range is -6dBmV to +15dBmV with a recommended SNR of 33dB

Upstream transmit Power Level : 47.0 dBmV

Quote:

Upstream Transmit Power: Anything between 28dB and 53dB is fine

I have since been told that my settings are fine, but the high SNR did concern me.

ic2 · 14-03-2007, 19:28

Hi,

can someone advise me the best way to get the tekkies to look at my readings without letting them know I have gone into the config page (as it looks like I am outside the optimum readings)

Downstream Receive Power Level : -8.56 dBmv
Downstream SNR : 27.97 dB
Upstream Transmit Power Level : 55.75 dBmv

Plus I am running Vista and through a Watchguard firewall so I would expect some slowdown, especially as the box is running IPS/ GAV:

Wed, 14 Mar 2007 19:24:52 UTC

1st 512K took 722 ms = 709.1 KB/sec, approx 5843 Kbps, 5.71 Mbps
2nd 512K took 550 ms = 930.9 KB/sec, approx 7671 Kbps, 7.49 Mbps
3rd 512K took 543 ms = 942.9 KB/sec, approx 7769 Kbps, 7.59 Mbps
4th 512K took 539 ms = 949.9 KB/sec, approx 7827 Kbps, 7.64 Mbps

Overall Average Speed = approx 7278 Kbps, 7.11 Mbps

So I dont want to make it hard for myself or is it a case of if it aint broken........

RedDragon · 14-03-2007, 20:16

Your upstream is at the high end but workable, your downstream is below what it should be.There is no reason why you shouldn't look at the config page. Some modems will cope with low levels better than others so if you are not getting any problems then fine, but if you start to get slow browsing etc the low levels will need looking at by a tech.

ic2 · 14-03-2007, 20:23

Quote:

Originally Posted by RedDragon

but if you start to get slow browsing etc the low levels will need looking at by a tech.

Browsing now very slow and the levels have moved south:
Downstream Receive Power Level : -9.96 dBmv

Spoke to India who tell me that everything is within the accepted range according to them and as I am going through a router its my issue but yesterday I was getting 8.10 M/bs and nothing has changed.

Do I need to call support during the day and take the router out of the config?

RedDragon · 14-03-2007, 20:59

Take the router out (it will save time as they will ask you to do this anyway)but these levels are no longer acceptable so unless it is a network problem,(in which case more complaints will come in and a network tech will be dispatched)you will need a tech to investigate the signal loss.

ic2 · 14-03-2007, 21:08

Router taken out but India still insisting signal levels are within acceptable range....want me to leave it connected (minus firewall) for 24 hrs for monitoring. Not sure about that

ic2 · 15-03-2007, 07:40

Strange...................at 06:15 this morning the signal level was:

Downstream Receive Power Level : -15.36 dBmv

but I could still download at 8.02 Mbps from the speed test on this site, perhaps last night was contention?

RedDragon · 15-03-2007, 08:16

If you're reading this right you're lucky to have a connection at all. It's obvious that your downstream is degrading but it's only a matter of time untill your upstream hits 61 dB (max) and drops the connection. It's probably a loose or faulty connection on the catv cable. check all connections are screwed on tight (finger tight will do) and not cross threaded.