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Standard User kritifile
(member) Fri 18-Nov-11 09:19:29
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Strange seasonal speed changes


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I moved to this property and signed up with BT last June. At first my sync speed was below expected for my line stats so I removed ring wires and had old-type sockets replaced with NTE5. Speed increased in line with stats.
Since then I have kept the same down attenuation of 43 dB and SNR of 6 dB. I do still have an old blind master socket in the loft, but as that's not easily reachable the engineer sent to investigate last year cut the cable to the socket in my bedroom. I now have a normal master socket but it is connected to the old blind master socket in the loft and I've lost the extension socket in the bedroom. If I want that back I have to run wire from the master.
But this is the strange performance. Last summer after optimising my connection as much as possible I had a download sync speed of on average 5500 kbps. When the nights got darker and the weather colder the sync speed increased until by December/January it was 6900 to 7200 kb/s. Then as the days got longer and the weather warmer the speed dropped. For a long time it stayed on 6500 kb/s or thereabouts, then dropped to 6000 kb/s. It did drop to 5800 for a time, but I had a phone fault then.
Anyway, I didn't put a fault report in until the sync speed dropped below 6500 kb/s, in fact only made it a serious report when it dropped far lower, I had distortion, fading, silent spells on my phone as well. At that time I switched from HH2 to a Netgear so I could use Routerstats. I learned that I had a far higher number of errors although the connection was holding and my SNR and attenuation were exactly the same as when i had over 7000 kb/s sync. Also I had a very large number of bitswaps.
Since the clocks went back and the weather got colder my speeds have started to increase again. Today I managed to sync at over 7000 kb/s, apart from one accidental modem reboot caused by a power cut I've had 6900 kb/s for the last five days.
I am wondering if this could be connected with the weather as I seem to connect faster in winter than summer. I can get no more than ADSL max, so I can never get a profile better than my best of 6.5 mb/s as I don't live close to the exchange. My exchange was supposed to have been WBC enabled last autumn but that never happened, now no date at all for any upgrade is shown by SamKnows although with my line stats I could maybe get improved speeds with ADSL2+. Infinity is a distant and unlikely dream for this exchange as it is still Market 2, only 3 providers if Virgin isn't counted.

Maybe this should be posted in Technical or Wholesale Broadband, but I am wondering if anyone has an idea as to why my connection speed improves when most people expect the opposite due to more interference and longer nights.
I don't know if this could be connected with BT Retail at all. I've never had any other provider at this address as when I moved here all others went through BTW, there was no LLU and my road isn't cabled. Now I could maybe get ADSL2+ buy moving as two LLU providers moved into the exchange recently, but I prefer BT to Sky and TalkTalk.

I have a beef about BT profiles, see them as a way to reduce traffic. For me they keep my throughput down to 1 m/s or more below sync speed and I know from experience that without profiles the only problem I ever had on a very poor line was sometimes being disconnected from the ppp session due to too many errors on a truly terrible and very long line. Now, different distance from exchange and no waterlogged cables and I am permanently a few bits below the next profile.
I did have a 5.5 profile when I was syncing at 6.5, still have it although I now have a 7 mb/s sync, so throughput is 2 mb/s below modem sync. In real terms my download throughput is always 500 kb/s below the profile.

But that aside, does anyone have any idea why my modem download sync is up to 1 mb/s lower in summer than in winter, with attenuation and SNRM remaining the same. My actual SNR has improved and I want to be able to turn my modem off at night, but if I do so I could get a lower resync speed if I switch on before 7.30 am. I am waiting impatiently for my profile to increase and don't want to risk slowing that process down. I had just under 3 days with a 300 kb/s speed increase, then had the unfortunate power cut at midnight that stopped it increasing, am now on the third day in the next profile step but have to wait for any change by BT, for them to increase the profile to 6 mb/s
Administrator MrSaffron
(staff) Fri 18-Nov-11 10:11:29
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Re: Strange seasonal speed changes


[re: kritifile] [link to this post]
 
Overhead cables to property and in summer it sags more and rubs on a tree/bush

Also cold copper conducts better, but not to the extent you are seeing.

Andrew Ferguson, andrew@thinkbroadband.com
www.thinkbroadband.com - formerly known as ADSLguide.org.uk
The author of the above post is a thinkbroadband staff member. It may not constitute an official statement on behalf of thinkbroadband.
Standard User kritifile
(member) Fri 18-Nov-11 11:10:47
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Re: Strange seasonal speed changes


[re: MrSaffron] [link to this post]
 
In reply to a post by MrSaffron:
Overhead cables to property and in summer it sags more and rubs on a tree/bush

Also cold copper conducts better, but not to the extent you are seeing.


Agreed, but the closest to overhead cables are the cables fastened to the external wall of the block of flats I live in, from the DP point. In this area everything tends to be underground.
The cable does run under the metal pipe carrying wiring for security lights. That's the only odd thing I can see here. Lots of trees, but as the cable is underground there the only effect they could have would be roots and trees don't lose roots in winter.
I know the effect of cold, but it's not that much colder in daytime than it was at night in summer yet. I would have thought there may be some sign in line attenuation but that remains steady all year round. The only correlation I can make is changing the clocks and days being longer or shorter. As more electrical equipment is used in winter than summer, I'm wondering if that is actually boosting rather than interfering? I know that doesn't make any sense, but my connection seems to be the reverse of others and the one I had on my old property. It doesn't make sense, when the speed dropped in May I assumed the line had become less efficient, but now in November the speed is increasing. It increased in November last year as well. I've only lived here for 18 months so don't know yet if it happens every year, just seen the same change this year as last so far. The only stats that change are errors and increased bitswaps (interleaved due to line errors) in summer, plus the SNR increase in mid-November. In the winter my line seems to run at just about the maximum its capable of with ADSL Max, 43 dB attenuation and a 6 dB SNR margin. I never expected to ever hit over 7000 kb/s but I did last winter and have just gone over that number now. Summer, average 6,400 - 6500 kb/s, sudden increase (along with increase of 2 dB SNR at lower sync speed), jump to 6900 plus for a week apart from a power cut lasting a minute around midnight when I resynced it just under 6800 kb/s, now jumped to just over 7000 kb/s with SNR varying between 6.2 and 6.6 dB. In the summer SNR never went over 6.2 dB and dropped closer to 5 dB at night, so to me that hints at some strange noise.
Weird.


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Standard User geordiekris
(experienced) Fri 18-Nov-11 19:08:34
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Re: Strange seasonal speed changes


[re: kritifile] [link to this post]
 
as an OR eng once put it to me, in the winter the copper contracts due to the colder weather thus casuing tighter joints better signal transmission in the summer the copper expands with the heat casuing looser joints and a worse signal strength, apparently this alos applies to aliminium cable as well. Again this info was supplied to me by an OR engineer

i can say whatever i want as i no longer work for the [censored]!
Standard User kritifile
(member) Fri 18-Nov-11 19:29:22
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Re: Strange seasonal speed changes


[re: geordiekris] [link to this post]
 
In reply to a post by geordiekris:
as an OR eng once put it to me, in the winter the copper contracts due to the colder weather thus casuing tighter joints better signal transmission in the summer the copper expands with the heat casuing looser joints and a worse signal strength, apparently this alos applies to aliminium cable as well. Again this info was supplied to me by an OR engineer

Thanks for the info which I'd more or less guessed at as I used to be an electronics engineer, but it shouldn't make that much difference I think.
I'll ask my ex-BT (pre OR) friend, but I figured that unless there was a jointing fault the extra noise and longer hours of darkness would have cancelled that out. It did where I lived before, but there the joints got waterlogged and the cable soaked up water when it rained., I've not heard of getting a +7mb sync speed with 43 dB attenuation, officially I think 6 mb is the max on an up-to-8 mb Max connection.
Administrator MrSaffron
(staff) Fri 18-Nov-11 23:29:35
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Re: Strange seasonal speed changes


[re: kritifile] [link to this post]
 
7 Meg sync at 43 db attenuiation is not impossible just rare, ADSL has often exceeded expectations, even with the high loop density the UK has now.

Andrew Ferguson, andrew@thinkbroadband.com
www.thinkbroadband.com - formerly known as ADSLguide.org.uk
The author of the above post is a thinkbroadband staff member. It may not constitute an official statement on behalf of thinkbroadband.
Standard User tommy45
(fountain of knowledge) Sat 19-Nov-11 00:16:55
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Re: Strange seasonal speed changes


[re: MrSaffron] [link to this post]
 
In reply to a post by MrSaffron:
7 Meg sync at 43 db attenuation is not impossible just rare, ADSL has often exceeded expectations, even with the high loop density the UK has now.
over the past 9mths my attenuation up/down has shown a slight increase from may onwards until October/November

when it started to decrease again,
But in my case the sync speed showed a upto 1mbit increase during the summer, and so far is around what it was last winter, all the bt line plant from house to cab and back to the exchange is underground

Standard User MHC
(legend) Sat 19-Nov-11 15:29:24
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Re: Strange seasonal speed changes


[re: geordiekris] [link to this post]
 
Wrong way round ... in a Krone type IDC or even the gel crimps expanding copper would make a tighter joint between the two cutting edges. But I doubt if that actually has very much effect as they are sprung loaded.





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M H C


taurus excreta cerebrum vincit
Standard User MHC
(legend) Sat 19-Nov-11 15:34:15
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Re: Strange seasonal speed changes


[re: kritifile] [link to this post]
 
One thought is that atmospheric moisture content is higher in the winter. The moisture will absorb some of the RFI which is abundant in the atmosphere from radio stations across Europe, street lights and other equipment. That will effectively improve teh SNR and a resync will take then reduce the SNR to the standard value and give you extra speed.

By how much? No idea, but it is one possible explanation for some changes.





~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


M H C


taurus excreta cerebrum vincit
Standard User kritifile
(member) Sat 19-Nov-11 16:50:42
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Re: Strange seasonal speed changes


[re: tommy45] [link to this post]
 
In reply to a post by tommy45:
In reply to a post by MrSaffron:
7 Meg sync at 43 db attenuation is not impossible just rare, ADSL has often exceeded expectations, even with the high loop density the UK has now.
over the past 9mths my attenuation up/down has shown a slight increase from may onwards until October/November

when it started to decrease again,
But in my case the sync speed showed a upto 1mbit increase during the summer, and so far is around what it was last winter, all the bt line plant from house to cab and back to the exchange is underground


7 meg is far higher than I expected to get with my stats, but I got up to 7.2 meg last winter and it's heading that way again.

Tommy45, my exchange doesn't have ADSL2+ so if I lived next door to it I couldn't sync above 8 meg, but logically I would expect to see a winter decrease, not the opposite, because of more RF noise in winter. InsteadI see a 1 meg plus decrease in summer compared to winter. If the exchange is ever upgraded I have no idea if I'll benefit as I get such weird summer/winter variations now and because ADSL2+ uses higher frequency bins they're more likely to be knocked out by noise I assume. All cables are underground here apart from the ones climbing the walls of the block but I'd expect that if there was a seasonal change it would be the same as yours.
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