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Some Questions For Dave or Ben (CS) Please.

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Some Questions For Dave or Ben (CS) Please.

Hi,

I joined Plusnet 28/11/2002 on wires only ADSL Home Surf 512K and paid an initial charge of £70.50 . I have my own router which I changed to an LINKSYS WAG54G V.2 Wireless router as the previous one was faulty. Things have been going slowly over the past week - (browsing the Web , email PN and this forum ) taking anywhere from 30 - 60 seconds between pages that I click on . Even when in email I send a message to TRASH. It seems to be working a lot faster today , but before it was worse than dialup. Any problems that you know of at your end? I have four other PC's ( my childrens) linked via Wireless.

I know that I can't use P2P on this service , but would like to (usage probably up to 2.5Gb/mth ) on top of the 3.5 or there abouts that I use normally per month. My concern is that I probably won't be able to get 2Mb as I'm not sure if I'm on the edge of line length from the exchange.

My exchange is Basingstoke Code : THBZ and I'm on DSLAM ID:-

BZ-ADSL-101 which was originally due for upgrade in June 2005 , then changed to July 2005 , then August 2005. It is now nearly November 2005 and still nothing heard!!!!
Here are the DSL Connection rates from my router:-

Downstream rate: 576Kbps
Upstream Rate: 288Kbps
Downstream Margin : 11db
Upstream Margin : 20db
Downstream Line Attenuation : 63
Upstream Line Attenuation : 31


Oh , by the way - my exchange has LLU (Easynet ) enabled.

My questions are :-

Will I ever be able to get up to at least 2Mb speed and be able to use P2P?

How do I find out how far away I am from the exchange ?

When are BT going to upgrade my DSLAM?

Will LLU help me to get faster speeds?

Would a WHOOSH test on my line give me any info. about Sig To Noise Ratio , true attenuation on the line etc , and how do I go about it?

I reckon that my max usage per month would be up to about 5 - 5.5 Gb/mth and only occasionally up to 10Gb. I don't think that that is too excessive.

Hope you can help with this ?

Kind Regards
Ian
20 REPLIES
shellsong
Grafter
Posts: 2,191
Registered: 03-08-2007

Some Questions For Dave or Ben (CS) Please.

My heart bleeds for you!-- With those noise and attenuation figures you must be very lucky to get close to 512kbs at all! Sad
I don't think anything other than cable or moving a couple of Km closer to the exchange could improve matters even with the best possible equipment at the exchange-- My commiserations!
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Some Questions For Dave or Ben (CS) Please.

upgrading to 1mbit, even on LLU is highly unlikely to happen within the next decade, sorry m8

If you want p2p, change account... otheriwse move to cable if u can, if u cant then broadband premier would be the move to go for, p2p on bb+ isnt good
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Some Questions For Dave or Ben (CS) Please.

Hi

You could upgrade to premier account , but a lot of users still get poor p2p speeds on premier, myself included .

Or you could find a isp that will give you good p2p speeds at all times , taking in to account that p2p can be effected by the number of seeds etc and you might never max you connection out d/l ing .

thxs
Community Veteran
Posts: 38,311
Thanks: 972
Fixes: 57
Registered: 15-06-2007

Some Questions For Dave or Ben (CS) Please.

Youi need to carry out some speed tests to see what is happening as you shouldn't be getting that slow browsing.
If the Plusnet or ADSL Guide speed tests show bad results you swill need to try the BT speed test as this bypasses the Plusnet network.
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Re: Some Questions For Dave or Ben (CS) Please.

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Will I ever be able to get up to at least 2Mb speed and be able to use P2P?

I would think so, yes, once BT MaxDSL kicks off.

Quote
How do I find out how far away I am from the exchange ?

www.samknows.com will tell you, as does www.dslzoneuk.net however, it is really the length of your line which of importance, not how far you are away from the exchange. The line could be going half way around your town before coming back to the exchange, even though you might be 50 yards from your exchange. That can happen!

Quote
When are BT going to upgrade my DSLAM?

It depends what you mean by upgrade. I have a feeling that ALL BT enabled exchanges already support MaxDSL speeds. It's just that BT haven't gone live with the technology yet. The reason I say this is - like you, I have 60dB line attentuation and the fastest I can go just now (or rather, the fastest BT will let me go) is half meg. However, my Draytek router is reporting the the maximum obtainable speed on my line is around 3.5mbits. Once MaxDSL becomes live, BT will introduce a whole set of new packages to ISPs allowing the line limits that they currently enforce to be dropped meaning you should easily be able to obtain 2Mbit on your line (I say this with confidence after speaking with a very helpful sales rep @ Zen Internet).

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Will LLU help me to get faster speeds?

No. Same technology but by passing BT. Ok, ADSL2+ is new but for your line attentuation will not benefit you. See:

http://www.internode.on.net/images/copyright/internode-adsl2-distance.jpg
http://whatismyspeed.sourceforge.net/demo/images/myimage.gif

for more information (particularly the 2nd image on the above links).

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Would a WHOOSH test on my line give me any info. about Sig To Noise Ratio , true attenuation on the line etc , and how do I go about it?

Yes, but probably nothing more than what your router is already telling you. Raise a support ticket using "contact us" to get PN staff to run a test for you.

Hope all that answers your questions.
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Some Questions For Dave or Ben (CS) Please.

Thank you to all who have replied with very helpful posts!!

Cheers
Ian
shellsong
Grafter
Posts: 2,191
Registered: 03-08-2007

Some Questions For Dave or Ben (CS) Please.

@paygo

Am I mistaken in thinking that the download SNR is the main factor for estimating the achievable speed-- subtract 6dB for each doubling of speed down to 10dB as the lowest really viable level.
gardeni would appear to be down at 11dB already-- I hope you can show me to be wrong?
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Some Questions For Dave or Ben (CS) Please.

I'm not really up to speed with the technicalities, but in short, yes, the SNR does affect the speed your line can run at and if that goes too low, the connection will become unstable. 10dB seems to be the magic figure that people quote as the "lowest safe SNR" but I have not actually seen any definite print anywhere which says this to be the case.

As much as your 6dB drop theory for each doubling in speed is correct, I'm not sure if this applies to DSL. I know from doing an audio engineering course that each bit depth of an audio signal gives you 6dB of dynamic range. So, CD quality (16-bit) audio gives you 96dB of dynamic range on play back.

However, I don't think it is as simple as this for DSL because DSL uses a whole collection of mini frequency bands on your line (called BINS) each with a bandwidth of 4.3125 kHz (see this rather good white paper on the technicalities) so as far as I can tell, there is not one SNR ratio at work here - there are numerous for each BIN that your modem uses on your line. Some BINS will have a better SNR than others.

My guess is - BT are just being safe (and milking money from us and ISPs). That is why they currently fix the rate at 0.5/1/2 mbit for their IP stream products. However, the truth of the matter is most peoples' lines can go much faster than these set limits. Infact, I'll post my Draytek stats:

Running Mode            :    G.DMT

State : SHOWTIME
DS Actual Rate : 576000 bps
US Actual Rate : 288000 bps
DS maximum Rate : 3744000 bps
US maximum Rate : 768000 bps
DS Path Mode : Fast
US Path Mode : Fast
NE Current Attenuation : 59.5 dB
Cur SNR Margin : 18.0 dB
DS actual PSDM(C) : 00000007
US actual PSDM(R) : 00003e77
ADSL Firmware Version : 41e2be2c


As you can see, it clearly says the line can handle 3744000 bps, 6.5 times faster than my current "actual" half meg link. Note that this figure does change depending on the line quality at the time.

As for gardeni, yes, 11dB is low. Maybe he should buy a Draytek (and they aren't cheap) or, borrow one, just to plug it in and see what the "DS maximum Rate" figure is - I'm sure it will be much higher than 576000 bps.

Maybe the SNR figure on routers is actually a kind of "average" across all the BINS that the modem is using. As such, once MaxDSL is main stream, I'll maybe see my SNR level drop to stupidly low levels (like 3dB) but using all available BINS on the line and still be able to get 6.5 times the speed I'm currently on. Maybe that's how it works?

Hope this sheds some light on the mysteries of DSL for you! Smiley
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Some Questions For Dave or Ben (CS) Please.

Hi @paygo,

I have been on the two different sites:- both say that I have COMPATIBILITY problems on my line.

"The line could have an incompatible product, such as ISDN or DACS, or other phone distribution system on it. "


I paid Plusnet £70.50 for BT to get a decent line in for me , as the original line was faulty , so I suspect that BT just connected in any old line just to get me up and runningHuh?

I wonder how I fair in getting BT to recheck my line for problems such as above?
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Some Questions For Dave or Ben (CS) Please.

It sounds like BT's database is wrong. According to BT, if a line has "incompatible rented products" on it, you can't get ADSL. This includes DACSed and ISDN lines. Such products must be removed before BT start an order to place ADSL on your line.

PlusNet are not the people who will "get you a decent line in" (so to speak). That is all BT's department. It wouldn't surprise me if they have just "connected you on any old line" available. That maybe one that is 10 years old, it might be one that's brand new.

Raise a support ticket with PN who can pass the buck to BT in this particular case as BT's database clearly holds incorrect information about your line.
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Some Questions For Dave or Ben (CS) Please.

If anyone is interested (and wants to prove me wrong, cause I don't actually know if I'm right here), this is where your 8 mbit figure comes from in ADSL.

The PDF I linked to earlier in this thread tells you the following information:

256 total BINS of 4.3125 kHz each, each capable of transmitting 15 bits on a good quality line. 32 of these are upstream and 244 are downstream.

So, with a bit of maths, out pops the following magic numbers that we all know and love Smiley

15*224*4.3125*1000/2 = 7245000 bits which is approximately 8Mbits downstream.

15*32*4.3125*1000/2 = 1035000 bits which is approximately 1Mbit upstream.

You have to multiply by 1000 to convert kHz to Hz and then divide by 2 since (I think) it will be a method known as Amplitude Modulation that is getting used on the BINS to encode your 15 bits and if I recall, the bandwidth of a frequency band using AM modulation is half of it's frequency spectrum.

So it is clear to me there must be loads of SNRs for each BIN and the modem will constantly analyse each of these and adjust the bit depth of the BINS to obtain the fastest speed possible out of your line.

Apologies if this post is off topic.
Community Veteran
Posts: 5,877
Thanks: 1
Registered: 05-04-2007

Some Questions For Dave or Ben (CS) Please.

Your posts look extremely interesting, but caould we have them in english or do I have to get Marius (my comms tech tutor) to translate on wednesday :razz:
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Some Questions For Dave or Ben (CS) Please.

Sorry, a lot of this is spilling over from when I did network communcations at university. Anyway, I better zip it before this post goes completely academical and off topic Tongue
shellsong
Grafter
Posts: 2,191
Registered: 03-08-2007

Some Questions For Dave or Ben (CS) Please.

Thanks paygo, that was quite a helpful insight-- particularly the Allied Telesyn white paper. Smiley