Kitz Forum
Broadband Related => Router Monitoring Software => Topic started by: NewtronStar on April 17, 2014, 08:02:05 PM
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Hello Guys & Girls and happy Easter ;D
I would like to understand how the Power dBm / dBmV works on BroadBand and as it's shown on most monitering programs it must be very important
All I know at the moment from research is it's decibels and millivolts (power ratio) and SNR seem to be part of this equation.
So lets give you my Power dBmV > 11.1 Downstream and 0.6 Upstream, and please could you put this in laymans terms ;)
Cheers
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I wrote a little bit about it here (http://www.kitz.co.uk/adsl/linestats_explanation.htm).
It is important, because the more power supplied, then the higher your SNR(m) will be, thus a higher sync speed. Our routers have the ability to up the power slightly if its struggling after say bitswap or errors. On adsl2+ its not uncommon to see 18dB upon sync but after time it may ramp up to 20dB.
However..... it should be bourne in mind that PSD masks play a huge part in this process too and will cut back power on shorter lines. The PSD masks are much an undisclosed feature.. all I know is there are supposed to be 5 different profiles depending upon line length (for adsl/adsl2+), but I dont know any actual parameters or what tones are masked. At one time I searched to find out more information but drew complete blanks on this subject.
When it comes to VDSL the PSD masks are different again.. and further complicated by multiple sub-channels, each having what appear to be their own parameters.
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The units for measuring power are dBmW (normally just referred to as dBm), not dBmV. I wrote a short explanation here: http://wiki.kitz.co.uk/index.php/Decibels#Decibels_used_as_power_measurement
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N*Star -- You might like to take a look at the last few posts to this thread (http://forum.kitz.co.uk/index.php?topic=13306.msg253206#msg253206), where 4c and b*cat were wittering on about this & that and the relationship between power (expressed as dBmW) & voltage (expressed as mV) of an audio circuit.
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Many thanks Kitz and Eric & my big Black cat BC for responding back, I am finding it hard to get my head around dBm and I am reading both your links it may take a few nights for it to sink into the grey matter, it's something I look at in the stats but don't really understand what it meens and how to interpret those figures from one line to another ???
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Hesitantly, I offer a link to a Wikipedia page on dBmW (http://en.wikipedia.org/wiki/DBmW) . . .
That page provides links to other related topics and, as a result of following them, etc, etc, one will eventually end up reading about stendec (http://en.wikipedia.org/wiki/Stendec). ::)
(As with any foray into Wikipedia, the result is a rapid deviation which ultimately homes into Mornington Crescent (http://en.wikipedia.org/wiki/Mornington_Crescent_%28game%29). :-X )
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Hesitantly, I offer a link to a Wikipedia page on dBmW (http://en.wikipedia.org/wiki/DBmW) . . .
That page provides links to other related topics and, as a result of following them, etc, etc, one will eventually end up reading about stendec (http://en.wikipedia.org/wiki/Stendec). ::)
I have to say BC thats was a good read ;D