Sky BB speed issues - improving a poor noise margin

[Tezcatlipoca]

As I've kind of hijacked the Sky BB 16meg thread from around page 5 onwards

http://www.cableforum.co.uk/board/sh...2&postcount=68


I thought I'd start a new one, just for my noise margin issues (& anyone else's if they want). I may try splitting & merging at some point, when I've got time to comb through the Sky 16meg thread.

So, from here onwards: http://www.cableforum.co.uk/board/sh...8&postcount=83

Originally Posted by Chrysalis

Matt what I should have told you to do is take the faceplate off and try the test socket, as this bypasses all the extenstion cabling stuff.

It should be easy, 2 screws come off and the front comes off like a lego piece, behind that you see another socket like the socket on the faceplate, plugin the router there as normal and see if the stats improve.

If they do then you need to do a more permenant fix in removing the ringwire.

The 4mbit you getting isnt a big shock considering your noise margin. Welcome to the world of adsl where its entirely possible to only burst to a fraction of the max speed.

Ah, hence dragon's mention of the faceplate.

Never mind, I can still try it.


Googling "removing the ringwire" led me to http://www.kitz.co.uk/adsl/lowSNR.htm & http://www.clarity.it/telecoms/adsl_faceplate.htm amongst others.


So, possible options could be....

1) Remove the ringwire. (I assume the phones still ring, & it's easy to reconnect if/when I move properties?). EDIT: Yes they do - the phone ring is apparently powered by the microfilter so the ringwire (orange, IDC terminal 3) is completely unnecessary (& is a cause of problems anyway - poor noise margin).

2) Fit a filtered faceplate to the master, & connect the router to it's ADSL socket. [awkward position though, & an ADSL extension cable would be very inconvenient].

3) Fit a modified filtered faceplate, such as the one Clarity sell, which has bits on the back to hardwire an ADSL extension to if you don't want to just plug the modem/router into the front ADSL socket (as well as the normal bits a filtered faceplate has to wire in normal phone extensions at the back). A new extension could then be run fed from the ADSL connections on the back of the faceplate - however, like option 2, an extension is not convenient.



Current router stats, Sky BB "up to 16mbps":

Originally Posted by Netgear DG834GT "Sky Broadband Box"

ADSL Link Downstream Upstream
Connection Speed 5728 kbps 768 kbps
Line Attenuation 41.0 db 28.0 db
Noise Margin 6.1 db 14.0 db

Previous router stats, Firefly BB 2mbps:

Originally Posted by Netgear DG834G v 2

ADSL Link Downstream Upstream
Connection Speed 2272 kbps 288 kbps
Line Attenuation 39 db 12.5 db
Noise Margin 17 db 28 db

[Paul K]

Just so that I don't have to trawl through that thread, have you had your line tested by the provider and did you try the test socket? If you tried the test socket and had the same results I would ask BT or whoever is currently parked on the line to sort it out as line noise can be caused by numerous reasons

[Tezcatlipoca]

I assume that line tests were done when I first got ADSL a year ago, & again when I migrated from Firefly 2meg to Sky "up to 16 meg".

Or do you mean some sort of additional tests?

I haven't tried the test socket yet - gonna do that at the weekend.

[Chrysalis]

your downstream synch is better then expected at least, but poor for your attenuation.

My line is worse my current upstream noise is now pretty high and it can barely do 448kbit upstream.

[Central]

Line attenuation does rise a little bit on ADSL2+

[Chrysalis]

line attenuation is static, on adsl2+ the reading is just taken firther up on the frequency range on a weaker part of the signal so reports a higher number.

[Tezcatlipoca]

Right, I tried out the test socket this evening on the BT master.

Definite difference.

Originally Posted by Netgear DG834GT via extension socket

ADSL Link Downstream Upstream
Connection Speed 5728 kbps 768 kbps
Line Attenuation 41.0 db 28.0 db
Noise Margin 6.1 db 14.0 db

Originally Posted by Netgear DG834GT via BT master's test socket

ADSL Link Downstream Upstream
Connection Speed 8096 kbps 768 kbps
Line Attenuation 40.0 db 27.5 db
Noise Margin 9.0 db 13.0 db

Synch speed of 8096 suggests to me it's actually on ADSLMax up to 8meg, rather than ADSL2+ up to 16meg???

Noise margin is definitely better via the test socket.


I ran some speed tests (CF, DSLZone, Dan Elwell's BB Speed Tester), yet they only came out slightly higher than what I get via the extension socket (between 3 & 4mbps for each socket, but closer to 4 for the test socket).

[Chrysalis]

yeah the 8096 seems to indicate a 8meg cap. Still a bit low for your attenuation but that just goes to show attenuation isnt the be all and end all of what you will get only a rough idea. Your line probably has a bit more noise on it then the average line with the same attenuation.

It probably isnt adsl max and I think it is actually adsl2+ but capped as the other guy noticed your reported attenuation went up which is common with adsl2+ over adsl. Your router should be able to tell you if you using adsl or adsl+. If you are on adsl max tho then sky may charge you as I am fairly sure their prices are only lower for their LLU areas, and adsl max would indicate you not on LLU, also if its adsl max it explains why your speeds havent gone up as BT operate a poor BRAS rate limiting mechanism that keeps you throttled for 3 days after the increase in synch speed and if the synch speed remains stable it will then increase the rate limit.

You already found the links yourself to ring wire websites so I guess you dont need to know what to do next.

remember also http://yarwell.blogspot.com/2005_08_...l_archive.html linked from the website you mentioned.

[Carl J]

OP is not on the non-LLU package, that only has an upstream of 448kbps as it's the BT Wholesale home max product. Definitely ADSL2+ which means capping at 16Mbit not 8.

[Chrysalis]

yeah sorry I didnt notice the upstream that defenitly explains why his speed hasnt improved as he will need to wait 3 days for BRAS to update. In that case 8096 with a 9db noise margin is pretty good then.

[Carl J]

No he won't. He's on LLU there is no BT style training period.

[Tezcatlipoca]

Yeah, from looking around, seems it must still be the Sky LLU service, as the upstream is still a nice full 768kbps.


I disconnected the ring wire yesterday.... instant improvement. I now get the same stats as if it was connected to the test socket.

Originally Posted by Netgear DG834GT

ADSL Link Downstream Upstream

Connection Speed 8096 kbps 768 kbps

Line Attenuation 41.0 db 27.5 db

Noise Margin 8.9 db 14.0 db

Did some speedtests at DSLZone...got a very nice 6meg, even with Alison downloading stuff at the same time.


From having a look around ThinkBroadband (formerly ADSLGuide) & Skyuser.co.uk, it seems like Sky have a policy of capping people's speeds dependant on line quality, with some people also being put on G.DMT (?) rather than ADSL2+.

It's apparently possible to get Sky to uncap your speed, & put you on ADSL2+, if you talk to "Tier3" tech support & they think your stats are good enough for it.

Originally Posted by Netgear DG834GT ADSL info

/usr/sbin/adslctl: ADSL driver and PHY status

Status: Showtime Channel: INTR, Upstream rate = 768 Kbps, Downstream rate = 8096 Kbps

Link Power State: L0

Mode: G.DMT

Channel: Interleave

Trellis: ON

Line Status: No Defect

Training Status: Showtime

Down Up

SNR (dB): 8.4 14.0

Attn(dB): 41.0 27.5

Pwr(dBm): 19.8 11.5

Max(Kbps): 9120 1120

Rate (Kbps): 8096 768

G.dmt framing

K: 254(0) 25

R: 12 16

S: 1 8

D: 64 8

ADSL2 framing

MSGc: 1 1

B: 254 25

M: 1 8

T: 1 1

R: 12 16

S: 1.0470 8.6153

L: 2040 208

D: 64 8

Counters

SF: 711208 711206

SFErr: 88 0

RS: 96724306 6045251

RSCorr: 539088 4

RSUnCorr: 948 0



HEC: 56 0

OCD: 0 0

LCD: 0 0

Total Cells: 230858165 0

Data Cells: 12459284 0

Drop Cells: 0

Bit Errors: 0 0



ES: 73 0

SES: 3 0

UAS: 47 0

Total time = 3 hours 22 min 41 sec

SF = 711208

CRC = 88

LOS = 3

LOF = 0

ES = 73

Latest 1 day time = 3 hours 22 min 41 sec

SF = 711208

CRC = 88

LOS = 3

LOF = 0

ES = 73

Latest 15 minutes time = 7 min 41 sec

SF = 27171

CRC = 6

LOS = 1

LOF = 0

ES = 6

Previous 15 minutes time = 15 min 0 sec

SF = 52931

CRC = 6

LOS = 0

LOF = 0

ES = 4

Previous 1 day time = 0 sec

SF = 0

CRC = 0

LOS = 0

LOF = 0

ES = 0

15 minutes interval [-30 min to -15 min] time = 15 min 0 sec

SF = 52930

CRC = 5

LOS = 0

LOF = 0

ES = 5

15 minutes interval [-45 min to -30 min] time = 15 min 0 sec

SF = 52931

CRC = 6

LOS = 0

LOF = 0

ES = 4

15 minutes interval [-60 min to -45 min] time = 15 min 0 sec

SF = 52989

CRC = 4

LOS = 0

LOF = 0

ES = 4

[Chrysalis]

Originally Posted by Carl J

No he won't. He's on LLU there is no BT style training period.

sorry misread you for saying hes got 448kbit.

If he is on LLU it doesnt mean he is on adsl2+ sky also have a upto 8mbit LLU setting which may well use adsl1, the only way to know for sure is get the info from the router. Its also possible he is on adsl2+ but just capped at 8096.

---------- Post added at 15:10 ---------- Previous post was at 15:03 ----------

yeah not only are you on adsl1 then you are also on interleaving mode, interleaving increases your latency and decreases synch speed to provide extra error correction to increase stability. good lines shouldnt need interleaving but it helps on poor lines.

I think you will benefit from adsl2+ so I would try and get on that if you can, I think its a strange policy from LLU providers to only allow the best lines on adsl2+ as it is beneficial in all regards even for larger lines since it has improvements in other things other then increased frequency range.

[Tezcatlipoca]

Yeah, I'm thinking of phoning Sky later in the week, to see if I can get through to "Tier3" & get them to try it out on ADSL2+.

Originally Posted by Matt D

Yeah, I'm thinking of phoning Sky later in the week, to see if I can get through to "Tier3" & get them to try it out on ADSL2+.

May I ask what you mean by getting though to Tier3 CS?