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Standard User adslmax
(knowledge is power) Sat 22-Feb-20 22:47:16
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Re: 3db SNR - DLM Parameters?


[re: RobertoS] [link to this post]
 
In reply to a post by RobertoS:
BT Wholesale estimator output, and BT Wholesale speed test Further Diagnostics.


I think wolvesmad already know this one!
Standard User RobertoS
(elder) Sun 23-Feb-20 00:47:49
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Re: 3db SNR - DLM Parameters?


[re: adslmax] [link to this post]
 
Other people, maybe even newbies and non-registered people, read these forums for information, help and advice tongue wink.

My broadband basic info/help site - www.robertos.me.uk. Domains, site and mail hosting - Tsohost.
Connection - Three 4G, tbb tests normally 35-45Mpbs down, 65Mbps off-peak, 9-24 up.
==================================================
"Democracy means simply the bludgeoning of the people by the people for the people." Oscar Wilde
Standard User BLaZiNgSPEED
(member) Wed 04-Mar-20 14:31:01
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Re: 3db SNR - DLM Parameters?


[re: RobertoS] [link to this post]
 
It seems like the BT Checker doesn't reflect real world performance.

Something really bizarre has happened with the BT checker for my post code and this I have noticed today for the first time!
This is the latest readings now...
High Low High Low
VDSL Range A (Clean) 78.1 55 20 14.2 49 Available --
VDSL Range B (Impacted) 75.5 49 20 12.1 40 Available --

Before it was
High Low High Low
VDSL Range A (Clean) 80 68.2 20 19 62.1 Available --
VDSL Range B (Impacted) 80 65.1 20 19 56.6 Available --

I cannot explain this drastic drop from the minimum 68.2Mbps to 55Mbps and 49Mbps for Impacted while before it was 65.1Mbps.

The highest now shows as 78.1Mbps. Nonetheless, this has had zero negative effect on my speeds.

Line 1
Downstream Upstream
Actual Rate [Kbps] 80000 19999
Maximum Rate [Kbps] 80534 19999
Noise Margin [dB] 6.30 15.00
Attenuation [dB] 17.90 0.00
Power [dBm] 13.00 7.50

I am still syncing at max 80Mbps and 20Mbps upload so far 27 days connection up-time! And noise margins have been at 6.30dB. Briefly it did drop to 5.80dB for a few days but the connection sync has been unaffected.

Last few days the noise margins jumped back up to 6.30-6.40dB and 27 days no drop-out at full speeds. BT Checker doesn't really make any sense, I do not believe in the last few days there can be such a drastic crosstalk that would make the estimated speeds drop to this low.

Anyway, it doesn't really matter what the checker estimates show. As long as the router stats sync at the max 80000, 19999 I suppose that's all that really matters! The fact I am still syncing at max speeds at 6+dB noise margins suggest there isn't any crosstalk yet.


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Standard User deleted
(deleted) Wed 04-Mar-20 17:09:37
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Re: 3db SNR - DLM Parameters?


[re: BLaZiNgSPEED] [link to this post]
 
Rather than using your postcode try using your telephone number and if that isn't recognised (if not on a BT Wholeslae line) use the address checker - entering your postcode and then selecting your address from the drop down box. Remember that not everyone on a postcode sees the same speeds.
Administrator MrSaffron
(staff) Wed 04-Mar-20 17:25:20
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Re: 3db SNR - DLM Parameters?


[re: BLaZiNgSPEED] [link to this post]
 
What checker says does not impact your sync speeds, so if started showing just 10 Kbps your sync would remain where is was.

Likely that another property in the postcode has feedback some sync data and things have been recalculated

The author of the above post is a thinkbroadband staff member. It may not constitute an official statement on behalf of thinkbroadband.
Standard User BLaZiNgSPEED
(member) Wed 04-Mar-20 20:30:29
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Re: 3db SNR - DLM Parameters?


[re: deleted] [link to this post]
 
Yes, I've tried using my telephone number to check. But I get
"There is no data available for this number. This could be either because it is not a BT line or it is a new BT number that has just been provided. Most new numbers will appear on the checker 24 hours after BT has installed the line.

If this is a new BT number and does not appear after 24 hours then please click here for further details."

I switched to TalkTalk with a new telephone number as part of the upgrade on the 3rd of February last month.

The old telephone number is cancelled. The new number has shown the same result last 1 month on the BT Checker https://www.dslchecker.bt.com/adsl/ADSLChecker.Telep...

I've read I have to wait around 6 weeks for this change to take into effect. Anyway, when I joined last month TalkTalk FTTC it was 68.2Mbps minimum 80Mbps max for clean line.

In fact the BT Openreach engineer came on the day of the install with a VDSL Faceplate upgrade and he checked his device and it showed 70Mbps minimum and 83Mbps max for my address.

However, the checker on the website https://www.dslchecker.bt.com/adsl/ADSLChecker.Addre... has changed today for the first time to 55Mbps Low and 78.1Mbps High which has kind of shocked me. Something I have never observed before since making the same test from October 2019 when my cabinet went live until today.

Good news is that my router has pretty much always synced at 80000/19999 Kbps from the very beginning since I've joined and consistently got 75-80Mbps in speed test. Line has so far been very stable for 27 days no drop-outs, so I am pleased so far. smile

I just don't understand why the speed estimates on the BT checker have changed so much. I would think if it was crosstalk then my noise margins would try to drop to 3dB to achieve max sync. But it has been averaging consistently above 6dB download and 15dB upload.
Standard User Zarjaz
(eat-sleep-adslguide) Wed 04-Mar-20 20:53:24
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Re: 3db SNR - DLM Parameters?


[re: BLaZiNgSPEED] [link to this post]
 
Why are you fretting about this ?? It is, quite simply, not worth worrying about.

You have a short line. It produces stable high speed sync.

Move along please, nothing to see here.

Standard User BLaZiNgSPEED
(member) Wed 04-Mar-20 21:56:33
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Re: 3db SNR - DLM Parameters?


[re: Zarjaz] [link to this post]
 
Many thanks for the reassurance, Zarjaz! smile

You are probably right, I shouldn't be worrying about these estimate figures!

I just wanted to make sure my speeds aren't affected any time for the foreseeable future. And I hope that if in case my router did re-sync next time due to power cut, etc that it would continue to sync at the full 80Mbps and not drop to 78Mbps.

That was my only concern, other than that I have no other complaints. Fingers crossed, it remains that way! smile
Administrator MrSaffron
(staff) Wed 04-Mar-20 22:26:10
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Re: 3db SNR - DLM Parameters?


[re: BLaZiNgSPEED] [link to this post]
 
I'll repeat - what the checker says is in no way going to influence how the modem resyncs

The author of the above post is a thinkbroadband staff member. It may not constitute an official statement on behalf of thinkbroadband.
Standard User deleted
(deleted) Fri 06-Mar-20 13:23:35
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Re: 3db SNR - DLM Parameters?


[re: BLaZiNgSPEED] [link to this post]
 
In reply to a post by BLaZiNgSPEED:
Many thanks for the reassurance, Zarjaz! smile

You are probably right, I shouldn't be worrying about these estimate figures!

I just wanted to make sure my speeds aren't affected any time for the foreseeable future. And I hope that if in case my router did re-sync next time due to power cut, etc that it would continue to sync at the full 80Mbps and not drop to 78Mbps.

That was my only concern, other than that I have no other complaints. Fingers crossed, it remains that way! smile


I don�t understand why you care if it drops to 78Mb! You wouldn�t notice, don�t worry about it.
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