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High loss of signal figure

peter10
Grafter
Posts: 231
Registered: 04-03-2009

High loss of signal figure

My normal speed is 11 - 12Mbps. This has dropped to 5-6 Mbps. According to my router I had a lot of disconnections at about 4-00 AM and the local loss of signal figure seems high!
Uptime: 0 days, 4:29:41
DSL Type: G.992.5 annex A
Maximum Bandwidth (Up/Down) [kbps/kbps]: 576 / 15,012
Bandwidth (Up/Down) [kbps/kbps]: 440 / 9,592
Data Transferred (Sent/Received) [MB/MB]: 3.35 / 27.96
Output Power (Up/Down) [dBm]: 12.5 / 20.0
Line Attenuation (Up/Down) [dB]: 16.5 / 30.0
SN Margin (Up/Down) [dB]: 13.5 / 12.0
Vendor ID (Local/Remote): TMMB / IFTN
Loss of Framing (Local/Remote): 0 / 0
Loss of Signal (Local/Remote): 65,536 / 0
Loss of Power (Local/Remote): 0 / 0
Loss of Link (Remote): 0
Error Seconds (Local/Remote): 851,958 / 0
FEC Errors (Up/Down): 15 / 33,023
CRC Errors (Up/Down): 102 / 189
HEC Errors (Up/Down): 14 / 6,778
Normal figures are :
Maximum Bandwidth (Up/Down) [kbps/kbps]: 776 / 14,496 Bandwidth (Up/Down) [kbps/kbps]: 440 / 13,432 with SN margin down of 3 and loss of signal local ~ 2.
Is this my Thomson router giving weird figures or is there a problem? The router is plugged into the main socket.
Thanks for any info.
12 REPLIES
Community Veteran
Posts: 19,099
Thanks: 434
Fixes: 21
Registered: 31-08-2007

Re: High loss of signal figure

All the disconnections will be the cause of the Noise Margin being at 12dB and hence the slower sync speed (Bandwidth down). Have you had any other problems with disconnections either before or since because those LOS figures are high!?
Maybe a Plusnet DC team member could have a look at your connection history as well.
Plusnet Alumni (retired) orbrey
Plusnet Alumni (retired)
Posts: 10,540
Registered: 18-07-2007

Re: High loss of signal figure

Indeed Smiley
<img src="http://ccgi.psmith12.plus.com/visradius/generated/image13373437403251.png" />
I would say that's the start of an intermittent connection issue that's slowed since the lowering of the profile. Probably worth running through the wizard at http://faults.plus.net and our faults agents will get it sorted for you.
GrahamC
Grafter
Posts: 257
Registered: 19-07-2009

Re: High loss of signal figure

This...
Planned BT Network Maintenance - Friday 18th May Midnight-6.00am
...seems a likely culprit.
cheers
Graham
Community Veteran
Posts: 19,099
Thanks: 434
Fixes: 21
Registered: 31-08-2007

Re: High loss of signal figure

Good point, that might have caused some disconnects of the PPP sessions, but that work would have been unlikely to a have caused a drop in sync, which it looks as though may have happened.
peter10
Grafter
Posts: 231
Registered: 04-03-2009

Re: High loss of signal figure

Thanks for all the help.Router stats seem to have settled and are

Uptime: 0 days, 9:09:07
DSL Type: G.992.5 annex A
Maximum Bandwidth (Up/Down) [kbps/kbps]: 576 / 14,976
Bandwidth (Up/Down) [kbps/kbps]: 440 / 9,592
Data Transferred (Sent/Received) [MB/MB]: 13.57 / 122.48
Output Power (Up/Down) [dBm]: 12.5 / 20.0
Line Attenuation (Up/Down) [dB]: 16.5 / 30.0
SN Margin (Up/Down) [dB]: 13.5 / 12.0
Vendor ID (Local/Remote): TMMB / IFTN
Loss of Framing (Local/Remote): 0 / 0
Loss of Signal (Local/Remote): 65,536 / 0
Loss of Power (Local/Remote): 0 / 0
Loss of Link (Remote): 0
Error Seconds (Local/Remote): 851,958 / 0
FEC Errors (Up/Down): 15 / 45,137
CRC Errors (Up/Down): 102 / 225
HEC Errors (Up/Down): 14 / 7,594
Normally connection seems to drop for about a minute every 4 - 5 days. However recently it has been reconnecting at a lower speed which has been cured by going into the router and disconnecting and reconnecting once but the SN margin has been staying at 3. Just over a month ago on the 10th April I had a few disconnections in quick succession and the SN margin rose and the slower speed stayed for about a week. Hope it is not an intermittent fault as they never happen when you want them to. Will raise a fault on Monday if more connection drops.
Thinking back I had a phone call last night about 9-00 and there was noise on the line but I know the caller has had problems so thought it was his line. Phone seems fine now and I've tried a quiet line test with a corded phone which was OK.



Community Veteran
Posts: 19,099
Thanks: 434
Fixes: 21
Registered: 31-08-2007

Re: High loss of signal figure

Sounds like keep an ear on the phone. Often easier (& better) to get these things fixed as a phone fault.
Shadowamd
Newbie
Posts: 6
Registered: 18-05-2012

Re: High loss of signal figure

Whilst your SNR is decent, CRC's (Cyclic redundancy check) is usually a sign of something wrong. But it depends on how much you have been downloading to be able to comment.. I work mainly with core networks and service provider / business networks so <1% is normally acceptable due to VOIP being real time it's so sensitive to drops.
Remember copper is sensitive to electromagnetic interference, don't run it near power or anything of that sort. Make sure your wiring is not loose in your socket.
Community Veteran
Posts: 19,099
Thanks: 434
Fixes: 21
Registered: 31-08-2007

Re: High loss of signal figure

CRC (and other errors) can increase even when not down loading, it's the underlying rate that is a better indication of problems. On the last stats at the moment those errors are OK, but then I'd hope they would be with that noise margin, which has gone up due to an intermittent joint somewhere by the sound of the information provided.
peter10
Grafter
Posts: 231
Registered: 04-03-2009

Re: High loss of signal figure

Thanks for all the help. My knowledge of broadband is very limited so I have been grateful to you. I have
not lost connection overnight so if (as seems likely) it is an intermittent fault and happens again I will go through the faults wizard suggested by Matt. I guess that if the line remains stable then the SN margin will drop and the speed increase.
This morning the router stats show -
Uptime: 1 day, 6:10:15
DSL Type: G.992.5 annex A
Maximum Bandwidth (Up/Down) [kbps/kbps]: 576 / 15,032
Bandwidth (Up/Down) [kbps/kbps]: 440 / 9,592
Data Transferred (Sent/Received) [MB/MB]: 66.39 / 901.63
Output Power (Up/Down) [dBm]: 12.5 / 20.0
Line Attenuation (Up/Down) [dB]: 16.5 / 30.0
SN Margin (Up/Down) [dB]: 14.0 / 12.0
Vendor ID (Local/Remote): TMMB / IFTN
Loss of Framing (Local/Remote): 0 / 0
Loss of Signal (Local/Remote): 65,536 / 0
Loss of Power (Local/Remote): 0 / 0
Loss of Link (Remote): 0
Error Seconds (Local/Remote): 851,962 / 0
FEC Errors (Up/Down): 15 / 97,339
CRC Errors (Up/Down): 102 / 562
HEC Errors (Up/Down): 14 / 30,759
Community Veteran
Posts: 19,099
Thanks: 434
Fixes: 21
Registered: 31-08-2007

Re: High loss of signal figure

If the line remains stable, yes DLM will eventually reset the Target SNRM. But those HEC are a bit high for the duration cf. the CRC's, I think there is still some residual noise on the line. Keep listening to your phone. If your line rental provider is Plusnet, there shouldn't be a problem ringing them whilst you can hear the noise and getting them to do a copper test ie. as a phone fault. You'll still have to do that whoever you pay line rental to, but don't mention the broadband when reporting a phone fault otherwise you are likely to get the run around.
Shadowamd
Newbie
Posts: 6
Registered: 18-05-2012

Re: High loss of signal figure

I work as a tier 4 SP engineer / architect highly certified with 10 years experience, so I hope I know what I'm talking about. You need data on the line to cause CRC's how can you drop frames or packet's if there is nothing to drop?
Easiest thing to do is contact your phone line service provider, get them to check the line for noise. If it requires an engineer to visit after testing, that's what needs to be done... I can see that the line isn't in a perfect state so just get in touch and they should be able to help you out.
Community Veteran
Posts: 19,099
Thanks: 434
Fixes: 21
Registered: 31-08-2007

Re: High loss of signal figure

So your modem/router isn't talking to the exchange then when you aren't downloading.  Huh    Eg. try looking at your overnight usage when your computer is switched off between midnight any 0800  Lips are sealed