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Author Topic: Sync rate locked?  (Read 17456 times)

sevenlayermuddle

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Re: Sync rate locked?
« Reply #15 on: April 28, 2010, 03:43:48 PM »

this interference could be anywhere between my house and the exchange?) 

In principle that's true, so certainly keep an open mind.

But (others may disagree here...  I'm by no means the forum's REIN expert ) I'd argue it's more likely be to be closer to your  home, and possibly even within it.    The router will be more vulnerable to interference that is generated nearby , simply because the interference signal decays with distance.  It's also possible that the interference is being injected into your phone line remotely and overwhelming the DSL signal before it reaches your home, but that would also be more likely closer to your home than the exchange, since it's easier to overwhelm a DSL signal that's already attenuated, rather than a nice strong signal where it leaves the exchange.

Routerstats should be able to draw 'bit-loading' graphs, which can  be useful.  If you see an obvious dip in the graph, it can give you a clue what frequency to tune on the radio, though in many cases it may just be general noise over many frequencies.  See link for a calculator that converts dsl tone numbers numbers to frequency...  http://www.kitz.co.uk/adsl/adsl_technology.htm



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Wildy

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Re: Sync rate locked?
« Reply #16 on: April 28, 2010, 06:44:30 PM »

Have had a look through the bumf about bitloading, and found the facility in RS (pic attached).  Would I be right in thinking I'm having real problems with tones 113 - 130?

As an aside, we got a letter from Sky today saying they're winding up the Everyday package and we're being upgraded to the ADSL2 unlimited package.  I daren't even guess what will happen to our connection then.

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waltergmw

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Re: Sync rate locked?
« Reply #17 on: April 28, 2010, 06:56:50 PM »

Hi Wildy,

With the exception of the pilot tone 64 you have noise problems wherever there are no blue "pencils" or short ones too.

ADSL2 should give you slightly better performance but more if your noise problems were cured.

Kind regards,
Walter
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jeffbb

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Re: Sync rate locked?
« Reply #18 on: April 28, 2010, 07:12:14 PM »

Hi
@wildy: RS provides the option to display bits and tone /SNR margin . See button next to SNR button . The advantage you can see the actual Margin /tone ,rather than having to calculate it from the bit loading and SNR.

Regards Jeff
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sevenlayermuddle

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Re: Sync rate locked?
« Reply #19 on: April 28, 2010, 07:51:41 PM »

Have had a look through the bumf about bitloading, and found the facility in RS (pic attached).  Would I be right in thinking I'm having real problems with tones 113 - 130?

IMHO, in addition to the Jeff an Walter's comments, it certainly looks a bit suspect and it'd be well worth tuning your radio into that area, around 500-550 kHz.  If there's a powerful AM transmitter then that would explain the big gap, but if you mainly hear buzzes and crackles then you'd probably be onto something.

Radio 5 live does cause problems in many parts of the country, at the lower frequency end (upper wavelength) of the old MW band.  But I'm not sure if these are the frequencies typically used.  I hope not.  

I do get a gap for radio 5 myself, but it's not as pronounced, or as clean-cut, as the gap you've posted.  Sorry I can't show you, my router died a few weeks ago and I'm using a temporary one, and haven't bothered setting it up for RS.

 I don't suppose there's a huge BBC Radio tower overshadowing the  end of your garden ?   :o

- 7LM
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Wildy

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Re: Sync rate locked?
« Reply #20 on: April 28, 2010, 08:36:51 PM »

Just reposting bitloading graph changed as per Jeff's comment. I've got no idea what this one means I'm afraid  :-[

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Wildy

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Re: Sync rate locked?
« Reply #21 on: April 28, 2010, 10:01:03 PM »


 I don't suppose there's a huge BBC Radio tower overshadowing the  end of your garden ?   :o


Nowt round here but speed bumps, do they work on adsl signals?
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sevenlayermuddle

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Re: Sync rate locked?
« Reply #22 on: April 28, 2010, 10:31:33 PM »

[Nowt round here but speed bumps, do they work on adsl signals?
:lol: Nice idea, but don't say it too loud or you might find some of the Indian ISP support centres take it seriously and add the topic to their scripts.   :D
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jeffbb

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Re: Sync rate locked?
« Reply #23 on: April 28, 2010, 10:58:18 PM »

Hi

List of   mw radio stations  in UK

Something very odd about your Bits tone /snr margin graph. Even where the SNR margin is very high the bit loading does not appear to be optimised .As an example around tone 133 where there is no bits allocated the snr margin is 17,18,19, 17 db ??

Never seen such a spiky  snr margin tone  .

Regards Jeff
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sevenlayermuddle

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Re: Sync rate locked?
« Reply #24 on: April 29, 2010, 12:18:00 AM »

List of  mw radio stations   in UK

@Jeff That's a useful link Jeff.  It does seem to indicate there's no high power transmitters around 500 to 550, which renders radio interference an unlikely explanation,  unless Wildy happens to live next door to one of the few low-power transmitters.   Correct me if I'm wrong, but wouldn't the high margin on these tones just be consistent with the fact that they had been unavailable in the past, and the router hadn't got around to swapping them back - or for that matter, the router hadn't bothered to swap them back as it had nothing to gain, since it could easily maintain its connection speed without swapping?  What do you think, Jeff?

@Wildy, in addition to Jeff's comments,  do you hear any marked buzzes/crackles on the radio - perhaps intermittent -  in the region I mentioned...? It's probably near the end of the dial (lower freq/upper wavelength) on the MW band?

BTW, RS is clearly incredibly useful but it's not very responsive in real-time.  If you think there's an intermittent problem, I personally find the native Netgear HTML interface is often better as it reports the SNRM with a refresh rate that's configurable right down to 1 second.  If you  have access to something like a small laptop, or better still an Ipod Touch or the likes, you can either listen to a radio, and/or wander around the house switching things on/off, and see an almost instant change in SNRM when the problem strikes.
 
- 7LM

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waltergmw

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Re: Sync rate locked?
« Reply #25 on: April 29, 2010, 08:57:46 AM »

@ 7LM,

The reason that I'd mentioned faulty ADSL equipment in the other noise-related thread was that I know BT O stipulate power output to reduce cross-talk, although I believe a larger problem exists when VDSL is deployed in the same cable. However that doesn't preclude any high-power capable device from causing difficulties in the same bundle.

A year or so back I came across a faulty analogue wireless phone which played mayhem with ADSL2+ signals whenever a call was made. The offending device was replaced with a modern DECT phone and everything returned to peaceful normality.

Kind regards,
Walter
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sevenlayermuddle

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Re: Sync rate locked?
« Reply #26 on: April 29, 2010, 11:05:19 AM »

The reason that I'd mentioned faulty ADSL equipment in the other noise-related thread was that I know BT O stipulate power output to reduce cross-talk, although I believe a larger problem exists when VDSL is deployed in the same cable. However that doesn't preclude any high-power capable device from causing difficulties in the same bundle.

Agreed, anything's possible.  That train of thought is particulary relevant as Wildy earlier mentioned that others in the street have similar connection speeds.

A year or so back I came across a faulty analogue wireless phone which played mayhem with ADSL2+ signals whenever a call was made. The offending device was replaced with a modern DECT phone and everything returned to peaceful normality.

I'm not surprised by that, the old analogue cordless base stations used to TX just off bottom of  the MW radio band, about 1.6MHz I think.  That's not so far from ADSL frequencies, and well within ADSL2+ frequencies.  I think opinions still vary as to whether DECT ever spells trouble for ADSL but, personally, I'd take it as a forgone conclusion for old analogue cordless.
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Wildy

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Re: Sync rate locked?
« Reply #27 on: April 29, 2010, 04:19:13 PM »

unless Wildy happens to live next door to one of the few low-power transmitters.  

Nope, only one on that map within about 50 miles of us is the Virgin 1242 one, I guess I can stop looking for cunningly painted masts now.

Will try and supply better answers/comments later, as I'm supposed to be working at the moment  :)
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coolsnakeman

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Re: Sync rate locked?
« Reply #28 on: April 29, 2010, 05:55:00 PM »

Is your phone line overhead or underground? There is alot of spikes going on there from what i am reading on that graph but excuse me for my lack of experience on those graphs i haven't really used them before so please do correct me if i am wrong. If you have overhead cabling and live somewhat out in the sticks there is still that possible chance of perhaps a tree branch knocking of your cable which wouldn't be caused by powerful winds just the slightest of wind can cause the branch to move and scratch of the cable this can cause noise spikes causing your BB connection to do these type of things i have seen this as a problem in the past for BB users that live out in the sticks. Off course underground cabling wouldn't be getting effected by such a thing however if it is underground do you live near a busy/main road or dual carriageway as the likes of lorries and cars and basically any vehicle type going over the road can cause vibrations which can also cause these spikes. There is a way OR can fix that sort of thing to reduce the amount of vibration going through the cables they will just put that down as an underground cabling fault. Try not to just look at REIN but look at the bigger picture cause there is other types of interference out there. If this is something beyond your premises then leave this to your SP to contact BTW to deal with this as long as you have eliminated your own domain and find no faults there then your job is done the rest is down to who you pay for the service cause at the end of the day thats what your paying for:)

Regards
Gary
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Wildy

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Re: Sync rate locked?
« Reply #29 on: April 29, 2010, 07:48:49 PM »

To the best of my knowledge the cables are underground the whole way here from the exchange, so I think tree-spotting is out for now. We're on the edge of town, though the exchange here also serves the next town over, a couple of miles down the road, and if BT's availability checker is to be believed can supply them with the same speeds as we're getting. It appears to be raining now but I'm off work tomorrow so will try and get busy with the radio and see if that sheds any light.

I'm also no expert on the bitloading malarky but I'll try restarting the router during quiet time tomorrow and see if that gets any improvement.

If nothing comes of that it looks like another call to India's on the cards. Thank God the calls are free  ;)
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