Speed vs Line Stats

[Elmlea]

Hello all,

Not sure if anyone might be able to help here. I've got an attenuation of 45dB so was hoping for around 8Mbit/s when I was connected, but it stabilised at 5017kbit/s which I figured I could live with. The noise margin, when I checked today though, has dropped to 1.3dB which seems bizarrely low, even though the connection was perfectly stable.

One quick reboot later and I'm still at 45dB attenuation, but noise margin's back to a more sensible 7.1dB. However, my sync speed's fallen to 4786kbit/s, despite having no extensions and being plugged into the master socket.

Does anyone have any advice on how I might be able to pull my speed up a little more?

[Isitme]

It is possble you have a fault on your line. Do you have the filter plugged into the Master socket first, with the router and any splitters plugged into it. Post your stats so we can see if anything obvious is wrong. If you have an NTE5, it may be better plugging into the Test socket, just in case the faceplate is faulty.
How to get your router statistics

[Elmlea]

Oh yes; been chasing ways to perfect my broadband connection since I was one of the long-suffering Virgin broadband subscribers in 05/06 when their contention issues ruined their entire network!

Filter in the test socket with the faceplate dangling off because it's hidden from view, then the only splitter after that runs a cable to the Sky HD box. In the test socket as I said, but there's still a filter in the other socket upstairs just in case, and I've disconnected the ring wire and other little tricks like that.

The router's plugged into another Belkin N router as per the guide posted here about connecting 2 routers together.

Line stats:

Downstream: Connection speed 4854kbps, Attenuation 45.5dB, Noise Margin 7.2dB
Upstream: Connection speed 796kbps, Attenuation 27.5dB, Noise Margin 14.4dB.

Approximately 0.92 miles straight line to the exchange.

[Isitme]

Could you try unplugging everything except the router, give it a few minutes to settle and take your stats again? Very often the the Sky filters are dodgy and do not properly filter the 'noise' from a Sky digibox.

Are your extensions dead, ie, no dial tone, when the faceplate is removed from the master socket?

[Elmlea]

Those stats were taken with everything unplugged. Now, a day later, I'm roughly the same; noise margin has fallen to 5.4dB downstream but everything else is the same.

[Isitme]

It is possible you have a fault on your line, or it may just be of a generally poor condition. Do you have any noise on your voice line? Plug in a corded phone on its own, into the test socket and dial 1 digit. Your line should be quiet with only a very faint hiss at most. Without noise on the line you are unlikely to get anything done. If you do have noise, report it to your phone rental provider as noise on the line. Do not mention broadband or you will be given the run-around.

[Elmlea]

Another plea for help. Some people have suggested speaking to Sky to be set on a "gaming profile," which apparently might help things.

I've just run a fairly comprehensive line checker, which gives me the following output:

BlueEther's stats checker at BlueEther's ADSL / ADSL2+ Stats Checker thinks my line is made of bog standard phone wiring.

BlueEther's ADSL / ADSL2+ Stats Checker

Please submit your stats with at least 6 hours uptime for the best results.
If your line is too unstable to gain 6 hours then here is an interpretation of the submitted stats:
Down sync is low (56% of the theoretical maximum).
You are on ADSL2+
SN margins vary by too much.
Attenuation looks normal.

Uptime:			0h 00m 00s 
Modulation:		ADSL2+ -  on Annex A
				(Up Stream)	/	(Down Stream)
Sync:				796	/	4660
Data Transferred:		/	
Attenuation:			27.3	/	45.5
SN Margin:				14	/	6.3
Power:					0	/	0
Vendor:				Generic	/	
Modem:			Generic
LoF:					0	/	0
LoS:					0	/	0
Error Sec.:				0	/	0
FEC:					0	/	0
CRC:					0	/	0
HEC:					0	/	0

You are synced at 4,660 kbps. This sync will have a max throughput of about 0.47 MiB/s or 3,868 kbps.


Your expected max sync depends on many things, mostly the quality of the line and the target Signal to Noise margin at the time of sync.
Expected max syncs are:
3db Fastpath: 11,182
6db Fastpath or 3db Interleaved: 10,105
6db Interleaved: 8,257


You appear to be on the standard Signal to Noise margin and with set.
Your sync is 56% of the estimated maximum for a line with and standard SNR at your line length (3,295 meters).
As your sync is not above 81% of the estimated maximum you might wish to investigate a potential problem.

You appear to have a noise issue on the line as the upstream and downstream SN margins vary by too much:
1) that has caused the DSLAM to sync you at a higher SNR on the upstream.
2) there was noise on the downstream frequencies when you synced that has now lessened. This noise is likely to return.
3) there is noise on the upstream frequencies now that was not there when you synced.
4) there could be faulty equipment on the line.

Obviously something's gone awry; it reckons I should get almost double the sync speed I'm getting, and the fact the SNRs vary so much show there could have been some problems with the line before?

Can I get Sky to try DLM again from scratch, or uncap the line, or try something else? Would turning off interleaving achieve much?