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Author Topic: Dslstats SNRm per Band  (Read 1259 times)

Sheepie

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Dslstats SNRm per Band
« on: December 06, 2016, 10:16:07 AM »

I monitor my FTTC connection using dslstats running on a Raspberry Pi and configured to upload to MDWS (user=Sheepie). The Downstream SNRm per Band for D1 looks very odd, like there is 1dB of noise quite often (dslstats running at 1 sample per 60 secs).

So I decided to run dslstats on a windows PC at a much shorter interval ( 1 sample every 10 secs) to try and figure out what is going on, and I do not see the same spikes. The graph at 10 sec intervals does have the odd spike but nowhere near like the 1dB seen at the 60 sec interval graph.

Which graph should I believe?

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roseway

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Re: Dslstats SNRm per Band
« Reply #1 on: December 06, 2016, 10:58:29 AM »

You should be able to believe both of them. DSLstats takes the values directly from the pbParams data (see Telnet Data --> pbParams) without any further processing, so what you see in the graphs is exactly what the modem is reporting.

I can't really explain the difference, except that these are only snapshot values at the times the samples are collected, and in reality SNRM is a continuously varying quantity. Internally the modem only refreshes its values at short intervals, not continuously.
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  Eric

Sheepie

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Re: Dslstats SNRm per Band
« Reply #2 on: December 06, 2016, 12:36:46 PM »

I did suspect it was getting the values from pbParams mixed up but no the telnet output shows it's correct.

With such erratic values in the D1 band I either have some noise somewhere then, or the [new] modem is faulty. I have a second line coming into the house in the same cable (ADSL2+) and that one is fastpath and very low noise and only a small amount of CRC errors.
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