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Author Topic: SNRM Step Changes Without Re-Synch  (Read 417 times)

tiffy

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SNRM Step Changes Without Re-Synch
« on: October 02, 2019, 03:43:36 PM »

Noted last night that I have had US & DS SNRM step changes (decrease) on my VDSL2 line which have occured without a re-synch, would have thought that such SNRM step changes would be the likely to be the product or bi-product of a line re-synch, for whatever reason.

Not complaining, hence the post in "BB Technology" as opposed to "FTTC and FTTP Issues" forum, this is the first time I have achieved a 3dB DS SNRM target since migration from ADSL to VDSL in June 2018, just curious how the changes came about without a line re-synch.

DSLStats snapshots attached for reference, note, they are on a 4 day "X" axis.

Edit: Axis correction   
« Last Edit: October 02, 2019, 04:59:26 PM by tiffy »
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roseway

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Re: SNRM Step Changes Without Re-Synch
« Reply #1 on: October 02, 2019, 03:56:01 PM »

>> they are on a 4 day "Y" axis

I think you mean a 4 day "X" axis, i.e. the horizontal axis.
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  Eric

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Re: SNRM Step Changes Without Re-Synch
« Reply #2 on: October 02, 2019, 04:25:58 PM »

changes like that are usually due to sudden changes to signal interference.  e.g. a disturber line disconnecting/connecting or interference from a device been turned on/off.
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tiffy

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Re: SNRM Step Changes Without Re-Synch
« Reply #3 on: October 02, 2019, 05:03:48 PM »

Quote
>> they are on a 4 day "Y" axis

I think you mean a 4 day "X" axis, i.e. the horizontal axis.

Thanks Eric, I was thinking "X" but typed "Y", likely an age thing !

Remembering from my long ago school days, "X is across and Y's up"
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tiffy

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Re: SNRM Step Changes Without Re-Synch
« Reply #4 on: October 02, 2019, 07:12:22 PM »

changes like that are usually due to sudden changes to signal interference.  e.g. a disturber line disconnecting/connecting or interference from a device been turned on/off.

Yes, I'am lucky to live in a low volume area where the majority of the local residents are retirees and still use ADSL service so not used to seeing much SNRM disruption or step changes unless via a line re-synch for whatever reason, thought that the "magical" 3dB DS SNRM target achievment might be significant but believe that any DLM intervention to bring about this would involve a line re-synch.
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kitz

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Re: SNRM Step Changes Without Re-Synch
« Reply #5 on: October 02, 2019, 07:34:31 PM »

One of your neighbours moving from adsl > vdsl can also result in a sudden drop in your SNRm.   My immediate and previous neighbour only had adsl2 and wasn't bothered about faster speeds.  When the new people moved in they got FTTC. 

ADSL can cause a small amount of crosstalk.  It's not as easy to spot as with fttc because it doesn't affect as many tones, but it is still there and even when she had adsl2 I could tell when she turned her router off as my SNRm would go up by about 0.5dB.  After the new people moved in, they came home from work one evening at about 6pm and bam I lost ~4dB immediately they switched on the router. :(   
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j0hn

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Re: SNRM Step Changes Without Re-Synch
« Reply #6 on: October 02, 2019, 07:54:52 PM »

Looks identical to a new crosstalker coming online.
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tiffy

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Re: SNRM Step Changes Without Re-Synch
« Reply #7 on: October 02, 2019, 08:30:38 PM »

Thanks to all for explanations, makes sense, just something I've not seen to this extent until now on my line.
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