Kitz Forum
Broadband Related => FTTC and FTTP Issues => Topic started by: michty_me on November 26, 2015, 01:37:20 PM
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On my MDWS graphs I occasionally see SNR spikes on the upstream and downstream. On the 25th of November, I saw my Upstream went from 6.8db up to 10.4dB and settled at 7dB. The Downstream went from 6.1dB up to 7.4dB and settled back to 6.1dB, This only happened for a couple of minutes. Any thoughts why I see this quite often?
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One of your line's (crosstalk) neighbours rebooting their modem?
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Hmm possibly, I've seen it at multiple times throughout the day. Maybe neighbours lines being reset during the day or DLM resetting in the early hours I guess.
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I see this effect too, on a regular daily'ish basis. Downstream SNRM leaps from 6 to 10 or 11, the downstream max rate leaps from the usual 39 mbps to circa 45 mbps, then at the next 15-sec point, drops back to normal.
My Plusnet service is the 40 mbps, but for the first 6 months was running at around 45 mbps max rate (the Plusnet profile ran at circa 39 mbps), then a month ago the max rate also dropped back to below 40 mbps. I had concluded it was probably the DLM trying to put the line to max possible achievable speed, but then some process chopping it back to the 40 mbps service max.
But I used to be on ADSL with 2 mbps (max) so it is more of a matter of interest than concern.
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I did wonder if it was DLM testing the line as after a few months of it my upstream speed has slowly increased from 16.5Mb to the full 20Mb. The Downstream has also gone from a max sync of 71Mb to 72.1Mb (This could just be sync times), My BT speed calculator has gone from always showing 71.5Mb to now showing a clean line should manage 79Mb but everyone knows the inaccuracy of that.
It is obviously causing no harm anyway but was just curious to see if anyone had an answer.
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Is it possible that your neighbour has an evil phone?
I used to have an evil DECT phone which stuffed my SNR when it went off hook, and I think the SNR stayed low(er) for the duration of the call, although iirc the transient at the start of the call was the really bad bit. Solution: I had to double-microfilter the phone to make it behave, and later on I just got rid of the phone entirely and had no phone at all on that line. I couldn't say whether this could have affected others, because at the time I didn't have neighbours with the right kit nor I did have a second line myself at the time.
Now I have zero phones and three DSL-only lines, but I'm afraid I have to say I've never done a reverse test, with me operating a phone at a neighbour’s house while simultaneously monitoring my SNR at my own house.
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I'm not sure to be honest. I haven't noticed any spikes as of late.
It doesn't seem to be causing any issues, I was more interested in seeing if there were any explanation to them. Not sure if it is a DECT phone issue as it just happens randomly, Sometimes in the dead of night, Others throughout the day.