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Author Topic: SNR drop in winter  (Read 2652 times)

adslmax

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SNR drop in winter
« on: November 06, 2014, 12:41:30 PM »

Is that true that FTTC SNR will drop more in winter than the summer season?

Code: [Select]
Downstream Upstream
Line Coding (Trellis) On On
SNR Margin (dB) 8.9 14.7
Attenuation (dB) 11.5 0.0
Output Power (dBm) 12.4 -0.7
Attainable Rate (Kbps) 90883 33108
Rate (Kbps) 79987 19999
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tommy45

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Re: SNR drop in winter
« Reply #1 on: November 06, 2014, 07:29:00 PM »

Can't see why the time of year would affect the snr, the attenuation can change a little due to the temperature outside, if really cold for a while ,or hot in the summer , But there can be other things during the winter months that may have a negative effect, such as xmas tree lights,Central heating boilers as well as associated moisture rotting the copper in particular  in the older joints
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NewtronStar

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Re: SNR drop in winter
« Reply #2 on: November 06, 2014, 07:53:34 PM »

It would sound that your SNRM does drop during evenings this is down to Radio propagation in the
E & F layer ionospheric refraction, during the daytime the E & F layer is kept at bay but just before or after sunset the e & f layer becomes stronger, and as the days are getting shorter the e & f layer stays with us much longer in the winter.

http://en.wikipedia.org/wiki/Radio_propagation#Ionospheric_modes_.28skywave.29

I would not say your snrm will drop further in winter time than summer time it's just the duration is longer in the winter.
« Last Edit: November 06, 2014, 08:00:52 PM by NewtronStar »
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kitz

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Re: SNR drop in winter
« Reply #3 on: November 06, 2014, 08:25:23 PM »

I agree with the others.. its not winter itself, but more chance of interference from electrical items.. and of course longer nights as mentioned by NS.  Theres an explanation of that also on the main site on the page about REIN ~ RFI in the atmosphere

If by posting your stats, then you mean youve noticed a sudden drop, then its more likely to be crosstalk.
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Bald_Eagle1

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Re: SNR drop in winter
« Reply #4 on: November 06, 2014, 08:38:30 PM »

FWIW, I have been logging stats/monitoring my FTTC connection since June 2011.

It does appear that physical line attenuation decreases slightly during colder weather & it increases during hotter weather.

With a decrease in line attenuation should come an increase in SNRM for those users able to achieve the full 80/20 sync speeds.

For users such as myself, only able to achieve around 21/4.5, an increase in SNRM above the target 6dB can actually lead to increased sync speeds when resyncing (SNRM will end up back at 6dB again).

So, my connection does appear to generally perform at slightly higher speeds during winter months.

Thankfully, I don't seem to be affected too much by increases in electrical equipment use and/or Xmas tree lights etc.

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Chrysalis

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Re: SNR drop in winter
« Reply #5 on: November 06, 2014, 09:03:56 PM »

I think the winter drop theory is from the following.

Lines with high loop loss suffer from a drop of snr at night, newt's line does it, my old adsl line used to do it, winter has longer nights, hence lower snr.
But not all line's drop at night, my FTTC snr is not affected by night and day and if anything is better at night.

Second things like christmas tree lights and central heating can cause interference, doesnt happen to me personally but seems to happen to some people.
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NewtronStar

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Re: SNR drop in winter
« Reply #6 on: November 06, 2014, 10:03:34 PM »

newt's line does it, my old adsl line used to do it, winter has longer nights, hence lower snr.
But not all line's drop at night, my FTTC snr is not affected by night and day and if anything is better at night.

It sure does Chry and without 24/7 stats running it was something that was missing to my eye how the SNRM plays out over 24 hours it's RFI in the atmosphere and you can see how the Uptream is not being affected by radio propagation to much because the US is using a lower frequency band than the higher frequency downstream band of D2 this is where the atmospheric RFI is getting into my longer line.

I would say to ADSLMAX to get the stats monitoring tools up & running 24/7 it gives you a
clearer picture of day to day month to month year to year line adjustments on your broadband.
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konrado5

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Re: SNR drop in winter
« Reply #7 on: November 06, 2014, 10:56:10 PM »

It is curious. My SNR margin in night is the same or higher than my SNR margin on the day. Moreover, my SNR margin in the winter is the same as in the summer.

Best regards
konrado5
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NewtronStar

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Re: SNR drop in winter
« Reply #8 on: November 06, 2014, 11:17:55 PM »

It is curious. My SNR margin in night is the same or higher than my SNR margin on the day. Moreover, my SNR margin in the winter is the same as in the summer.

Best regards
konrado5

That would indicate your line does not suffer from RFI  :)
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