Hi ukhardy07 - you know me as snadge from DSLzone

What do you reckons the chances they didnt actually do anything to your exchange in response to your letters and emails etc and it was fixing a problematic exchange (they were already working on) that yours was daisy-chained too that sorted the problem...?

I think this was probably the case however if nobody complained I doubt anything would be done.

I wish I never switched from o2 ... just like many others, and if I go back to BT/o2 I can not get the legacy package I was on and would have to pay through the nose at BE* to get my connection back.

I have to admit my pings last week were real bad and throughput suffering but past 5 nights or so its gone backwards a bit , still some latency issues but instead of 100-200ms most of the time they are 30-40ms with 5ms jitter half of the tests AND 40-80ms and 20ms jitters the other half of the time...no loss of throughput, so I think a dodgy exchange I was daisy chained to may have been upgraded OR Iam just hitting lucky past few days.

Yes the o2 packages now are totally unattractive and perhaps this attracts more customers to sky. It's good to see you've had a good few days. I think that sky are dealing with these issues so all we can do is wait.

BE charge higher but I've also read a fair few issues recently with their network.

to make matters worse my broadband already on SVBN but phone is not and because the phone has to be moved over DLM has to be restarted so i will have 10 days of [censored] speeds and DLM will finally settle on 15Mb again like last time when my line is capable of 18Mb and im gunna have to call up to get it un-capped again...which is hit & miss, this time i may not be so lucky and end up stuck with 15Mb or less (ive seen 13Mb syncs on 26db lines by SKY's DLM)

You have to remember that DLM is very risk averse. DLM aims for stability and not speed. On a line that is not entirely perfect the speed will be capped slightly. A bonus of DLM is that the line is stable, doesn't drop and customers aren't complaining of a dropped connection.

A large percentage of customers have a far from ideal setup. Plenty of people connect to an extension and then have an argos style DIY extension plugged in there... Sky have to provide these people an ok connection.

It's definitely too quick to reduce peoples speed in my opinion but it does provide a very stable connection for most people - regardless of their internal setup.

But yes - my complaints probably went on deaf ears.

& also hello there.. I also left the forum over at dslzone as it sadly died out. The last time I logged in it asked me to change my password and I simply gave up. The demise really started for me when the virus got in a while back

Sad to see you've not had a great experience though! I know you had things pretty sorted over on o2 at a 3db noise margin.

Edited by ukhardy07 (Thu 22-Mar-12 00:06:10)

Hi ukhardy07

Ive seen about 50+ new connections on their forums, guided new users from sign-up to post-dlm and not one connection has gotten the correct speed for the line, most of them came from o2 or other ADSL2+ providers and said they get nowhere near what they had before and their line attenuation confirms this, Sky always blame noise...but all of a sudden their line is noisey since moving to sky? lol...yeah I get DLM is sensitive and users may have had a small amount of manageable noise on previous ISPs and DLM wants to set the line with NO noise at all...but this shouldnt drop syncs by 10-20% on average (which is what seems to happen on DLM) the worst ive seen like I say was 13Mb on a 12db line but most the time its about 20% less, mine was 15Mb on an 18Mb line....no errors at all on 18Mb confirmed by sky last week, my friends was 16Mb on a 20Mb line...he now has 20Mb and no errors - a few more of my friends are in the same boat, now if it only happened to the odd person (as has been suggested by Sky themselves) then whats the chances that me and 4 of my friends and my neighbours all get the same results? nil...unless just about everyone gets same treatment.

I think its more in the Power Management Module in the ASSIA software, the PMM dynamically adjusts/sets the Output Power on the line...it takes into consideration energy saving figures entered by the ISP - a small decrease in output power in dBm and therefore a small decrease in speed can have a massive saving in energy consumption, I think this is why DLM falls short of the mark, because SKY either deliberately or unbeknown to them have unrealistic energy saving figures entered and its being restrictive of output power and thus achievable speeds, as the Output Power in signal (dBm) increases by 3dBm the Energy Consumption doubles on previous figure, so as you can see a lot of money can be saved here if you slightly restrict speed a little, combine all this with forcing 100% error free line then this is why you get speeds lower than what your line is capable of, like I say mine was 100% error free on SKY's system on the 18Mb profile, so the PMM restricted 3Mb sync from me (15Mb) to further save Sky money, had nothing to do with stability...both syncs had the same 7db Noise Margin which further indicates lower power output because signal to noise ratio is less, if output power was same on both sync rates then the Noise Marging would have been greater on the 15Mb sync.

Yes I got sick of that forum too...it kept resetting and not working properly...some of tse users that were left were getting a bit snotty too with users who became part timers...

nice to see a familar face - or should I say 'name' hehe

Edited by paulb100 (Thu 22-Mar-12 22:58:11)

I find what you just wrote very interesting.

I too was restricted. I have my line set to an 18mbps profile now (to get the 1 mbps upload) but in practice I get around 15 mbps.
Sky DLM set my line to 13.3 mbps however it only ever synced at 13.2 I believe.

This was on a new line...
When I first saw my line synced at 13.3 mbps I assumed that was the best I could get. Largely because I had a 7db noise margin. I hadn't thought of the output powers.

Whilst complaining about these speed issues sky changed my profile manually. I suddenly saw 15mbps.

I do totally take your opinion on board now. I've never seen a DLM capped line with a noise margin above 8db - yet once it's uncapped I've often seen several more mbps and the noise margin only drops to 7db.

All in all though when it works and when it's finally uncapped it works well. Even if sky try to convince you that the line cannot handle anymore speed .

yup it does work well once sorted and the sagemcom router is actually quite impressive, its whopping my beloved netgear GT with Wi-Fi in same 'G' mode for reception and is stable as hell (not one dropout since last sync weeks ago)... my line/exchange does have its problems on paper but in practice its spot on at moment...just hope it doesnt get worse...other than that Iam happy enough I suppose, 6 months free then £7.50 month...cant go wrong.. the only thing is they have new offer on of 6 months half price..I just hope this doesnt bottleneck it further and thus augment the latency/speed problems...

Aye the Power Output theory has all the evidence there too support it, Sky even told me themselves that DLM can lower the line rate without changing the Noise Margin itself (when I queried why me & my 4 friends had same NM on extremely different sync rates before and after un-capping) - that confirms output power is being reduced, its even documented by assia in the link I supplied, assia licence out the software to ISPs to run on their Dslams/Isams - someone who brought it too my attention said he monitored his output power during 10-day DLM and it did not go above 10dBm which managed a 13Mb sync on his 17Mb line with a 7db NM - 10dBm uses 10mW of energy - after getting it un-capped he was on 18dBm with 17.7Mb sync and still a 7db NM, 18dBm uses 64mW of energy - so as you can see in his line as example Sky were saving 80% in energy by giving him a 20% lower sync...now imagine how much they would save doing that too all 3 million customers... assia qoutes their default settings (which I dont think sky are using, they have obviously set it higher) save around £500,000 per year for every 1 million DSL lines...so DLM's PMM on default would be saving SKY about £1.5 million per year - now all lines vary but in example above they saved 5 times more money, you can easily see SKY saving TENS of millions from this 'sneaky' process, shorter lines capable of faster speeds would be saving them the most money when restricted.

just as reference, heres Output Power in dBm VS Energy Consumption in mW so you can see what kind of money can be saved. DSL can use anywhere up to 26dBm ,

0dBm = 1mW (one thousandth of a watt)
3dBm = 2mW
6dBm = 4mW
9dBm = 8mW
12dBm = 16mW
15dBm = 32mW
18dBm = 64mW
21dBm = 128mW
24dBm = 256mW
26dBm = 400mW
you can see the trend here....

I think Sky have gotten greedy and turned up the savings knob a bit on the PMM and using the fact that DLM is known to sync a little lower (and thats all it should be to be get rid of tiny amounts of weak tones to make a more stable line) as a 'cover' for whats really restricting it by a large amount.

A friend of mine has just been through DLM. They got a sync set to 4 mbps. It synced just short of this. Attentuation of 57db.
After having the line uncapped and set to 10mbps profile it's only syncing at 4051 kbps.

In this case I don't think the output power was restricted? Perhaps it's only the shorter lines that are subject to such 'tough' measures?

I know a few people with long lines who have switched over and haven't complained of significantly slower speeds.

I'd be interested in collecting results or something.

its defo the short lines its more noticeable on, I have seen one connection on Sky's forum recently that was sync'd about were it should be...

me and four of my friends and one neighbour all had same thing...whats the odd's of that happening if it were just a fraction of people = plus like I say, I see a hell of a lot of it on Skys forums... it doesnt mean it happens 100% of the time like, it could well be that many factors come into play such as energy consumption on that particular ISAM/Exchange.

shorter lines can go with less energy on the output power and still gain reasonable syncs, so it would be these lines that would save the most money on evergy savings and also the 'type' (short) of line that would be best suited to energy saving tweaks.

reps dont always get it right either..I asked for mine to be uncapped at 15.4Mb and he said he done it and I asked him to confirm it and he said "should have no problems" (when lowering SNR Margin) - however he got my router to sync at 18,013k - no matter how low I got my NM it would not move above that 18,013k which means instead of "un-capping" it he simply shunted it up from a 16Mb profile to an 18Mb one.

All the lines ive seen capped then un-capped always have the same 7db NM which shows it must be the Output Power thats being changed.. my friend has 16,000k / 7db before , then 19,999k / 7db after. When I queried Sky about all this they said my line was restrictre because DLM must have thought it was unstable (even though I never had one dropout)...however, after 3 weeks on 18,013k I contacted Sky and they sent me an email with copy/past of my line results and it showed ZERO errors for entire period..lol

Personally, I think DLM is really sensitive to both predicting how stable a line is and a bit greedy when applying energy savings .

what I will do is create a spreadsheet and every new sky connection I will enter the results and we can see whats what....sound good? that way we will get a picture of whats happening...I spend a lot of time on Sky forums helping anyway so...

Edited by paulb100 (Sun 25-Mar-12 19:40:15)

It's really interesting. Especially if shorter lines are restricted more than longer lines.

If DLM was entirely sensitive to poor line conditions you would think that longer lines would have a greater reduction in speed to maintain stability. The truth that we are seeing is that shorter lines are being restricted more (as a percentage) from what I can see. Although this may not be the case...

Also sky do not have an 'uncapping' system as such. They can only apply profiles. If you asked to be uncapped they just raise you to the profile above.

The way the sky staff seem to be taught is incorrect.
E.g. if my line syncs at 13 mbps. If I ask sky to uncap me they apply a 16 mbps profile.
Say I now sync at 15 mbps with a 7db SNR...

If I now ask sky to raise my profile to the 18mbps profile. If they did this I would still sync at 15 mbps with a 7db SNR (or somewhere around this speed)

Sky somehow seem to believe that increasing the profile from 16 mbps to 18 mbps would cause me great instability as they are apparently 'pushing too much speed down the line.' When in fact it's no different to the 16 mbps profile in this situation.

Trying to explain this to them and they have no idea.

It's like I've just had an issue with my line speed. The woman was saying that REIN was the problem. My SNR was only fluctuating from 6.5 and 7.2 db. Clearly not REIN. I told her this and she still said outside interference wouldn't change your SNR.

TBH to sum up sky customer services and even CST have very lacking knowledge. Even networking thought that the solution to my throughput problems was to turn my devices off standby to reduce REIN. My sync was stable for 100s of hours at a time too.

Anyway keep me informed on this. DLMs introduction was possibly an avenue into reducing power levels.

you would think when you ask to be uncapped it would just straight onto the max 20Mb profile regardless of what the line is capable of, if it works like any other LLu ADSL2+ ISP the line will just sync at the max attainable rate with a 7db NM....and no more..

like you say a lot of the reps dont know how it really works and how too apply our requests.

the longer lines seem to be more but percentages are usually about the same when I look at it..15-20% sometimes a bit more...sometimes less... ive seen 8Mb lines on under 4Mb which is 50%..!! long line would be more sensitive to DLM's restrictions due to line length and errors etc.. thats why I think they may get hit harder.

I asked Sky for more info on DLM and they refused to hand it out as "sensitive information" - yet you can go on assia website and learn all about it there - I emailed assia asking about PMM on DLM telling them my ISP (a large UK ISP) may be using the PMM aggresively and explained about it but didnt mention names....needless to say they did not reply... I may try again from diff email asking for more info for my "tech site" hehe

can you tell me your stats (for my spreadsheet)
I need:
Sync rate after DLM finished and the noise margin
Sync rate after you got line uncapped
Line Attenuation

my spreadsheet has those and 'exchange' , 'estimated sync' and 'difference' (uncapped minus capped) - although Im wondering if I need two colomns for differences.. one for people who managed to get uncapped so we have physical evidence of difference and one that shows difference from estimated speed,

can you tell me your stats (for my spreadsheet)
I need:
Sync rate after DLM finished and the noise margin
Sync rate after you got line uncapped
Line Attenuation

Estimated speed during sign up was 5 - 10 mbps

LINE SPEEDS:

Sync after DLM: 13320 kbps
Upstream: 1105 kbps

After uncapping and having the 18 mbps profile applied (for the 1mbps upload)

14415 kbps downstream - sometimes syncs higher at almost 15 mbps.
1161 kbps upstream

Attenuation: 30.5 db down
18.9 up

In all cases SNR was 7db

If you notice sky always give quite conservative estimates too.

Edited by ukhardy07 (Sun 25-Mar-12 22:31:26)

i did notice that hehe - ages ago...

I have just read this on kitz which seems to mention other reasons for power cut backs on healthy lines could be to aid in prevention of cross-talk - so SKY's DLM may be making the carrier channels (tones) weaker in an attempt to do just this, also combined with sensitivity to line stability it could be that SKY just want less people contacting CST with problems...even if it means 20% speed reduction for most people...

thanks for your details...gone into my spreadsheet, i will post it up once i have a healthy amount of stats