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Standard User WilliamGrimsley
(committed) Tue 04-Apr-17 19:12:50
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Why Does An Incoming Phone Call Affect Upstream?


[link to this post]
 
I've always noticed that when we having an incoming phone call, there are several upstream CRC's. Why does this happen? Is it because the upstream spectrum is closer to the phone signal's?

Sync: 35133/7900 Kbps.

Edited by WilliamGrimsley (Tue 04-Apr-17 19:14:36)

Standard User micksharpe
(legend) Tue 04-Apr-17 22:41:39
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Re: Why Does An Incoming Phone Call Affect Upstream?


[re: WilliamGrimsley] [link to this post]
 
That is correct.
Standard User Banger
(eat-sleep-adslguide) Tue 04-Apr-17 23:20:20
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Re: Why Does An Incoming Phone Call Affect Upstream?


[re: micksharpe] [link to this post]
 
Always remember my Telecoms lecturer at college saying voice occupies 300-3400hz on the telephone line. Upstream isn't that far off.

Tim
www.uno.net.uk & freenetname
Asus DSL-N55U and TP-Link WD9970 on 80 Meg LLU Fibre
http://www.thinkbroadband.com/speedtest/button/14910...


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Administrator MrSaffron
(staff) Tue 04-Apr-17 23:45:33
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Re: Why Does An Incoming Phone Call Affect Upstream?


[re: micksharpe] [link to this post]
 
For ADSL, on VDSL2 things are different a quick version of the bands https://en.wikipedia.org/wiki/VDSL

http://www.niccstandards.org.uk/files/current/ND1436... and note the chat about band plans

The author of the above post is a thinkbroadband staff member. It may not constitute an official statement on behalf of thinkbroadband.
Standard User eckiedoo
(fountain of knowledge) Wed 05-Apr-17 07:25:49
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Re: Why Does An Incoming Phone Call Affect Upstream?


[re: WilliamGrimsley] [link to this post]
 
I wonder if this also occurs on out-going phone calls, particularly to the same numbers if the CRCs are confined to certain numbers on the incoming calls?
Standard User WilliamGrimsley
(committed) Wed 05-Apr-17 11:51:05
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Re: Why Does An Incoming Phone Call Affect Upstream?


[re: Banger] [link to this post]
 
Thanks for explaining. I don't notice any upstream CRC's with outgoing phone calls. Maybe this is because Upstream data is sent from the EU instead of receive.

Sync: 35133/7900 Kbps.
Standard User tommy45
(knowledge is power) Wed 05-Apr-17 12:21:39
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Re: Why Does An Incoming Phone Call Affect Upstream?


[re: WilliamGrimsley] [link to this post]
 
In reply to a post by WilliamGrimsley:
Thanks for explaining. I don't notice any upstream crcs with outgoing phone calls. Maybe this is because Upstream data is sent from the EU instead of receive.
It's a minor line fault, As there should be no interaction going on between data And PSTN services My VDSL line started doing this but i see around 20 error seconds whilst the phone is ringing , it is in part to do with the increase in voltage that occurs only whilst ringing,

Edited by tommy45 (Wed 05-Apr-17 14:38:43)

Standard User WilliamGrimsley
(committed) Wed 05-Apr-17 12:54:52
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Re: Why Does An Incoming Phone Call Affect Upstream?


[re: tommy45] [link to this post]
 
I hope not, just had a telephony fault fixed and the broadband boost engineer told me my line pair was "perfect".

Sync: 35133/7900 Kbps.
Standard User MHC
(sensei) Wed 05-Apr-17 13:33:14
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Re: Why Does An Incoming Phone Call Affect Upstream?


[re: tommy45] [link to this post]
 
In reply to a post by tommy45:
In reply to a post by WilliamGrimsley:
Thanks for explaining. I don't notice any upstream crcs with outgoing phone calls. Maybe this is because Upstream data is sent from the EU instead of receive.
It's a minor line fault, As there should be interaction going on between data And PSTN services My VDSL line started doing this but i see around 20 error seconds whilst the phone is ringing , it is in part to do with the increase in voltage that occurs only whilst ringing,


And not much you can do about it! Hitting the filter with a burst of 75v cadenced to provide the ringing will always have an effect.


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

M H C


taurus excreta cerebrum vincit
Standard User WilliamGrimsley
(committed) Wed 05-Apr-17 13:40:16
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Re: Why Does An Incoming Phone Call Affect Upstream?


[re: MHC] [link to this post]
 
Oh yes! It still fascinates me about how it all works!

Sync: 35133/7900 Kbps.

Edited by WilliamGrimsley (Wed 05-Apr-17 13:40:46)

Administrator MrSaffron
(staff) Wed 05-Apr-17 13:48:51
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Re: Why Does An Incoming Phone Call Affect Upstream?


[re: WilliamGrimsley] [link to this post]
 
A perfect line pair can still be subject to burst radio frequency interference

The author of the above post is a thinkbroadband staff member. It may not constitute an official statement on behalf of thinkbroadband.
Standard User WilliamGrimsley
(committed) Wed 05-Apr-17 16:58:34
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Re: Why Does An Incoming Phone Call Affect Upstream?


[re: MrSaffron] [link to this post]
 
Understood. The downstream SNR margin can drop by about 0.4 dB when there's a phone call.

Sync: 35133/7900 Kbps.

Edited by WilliamGrimsley (Wed 05-Apr-17 17:09:16)

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