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Author Topic: Increasing Down snr increases line speed!  (Read 735 times)

parkdale

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Increasing Down snr increases line speed!
« on: May 19, 2017, 07:09:26 PM »

Increasing Down snr increases line speed! I'm a bit perplexed at this ???
As you can see in the attached pics my line has had a resync but the snr down values have gone from 20db to 24db, same with upload speed increase of 4db.
The bit that I don't get is the increase in attainable speed both up and down, this is the third resync this week after 12 months of stable line.
I was getting 19db down untill AVM issued a firmware update, this had a knock on of increasing my download by 1db.
Feb stats are what was normal.
My snrm looks like it's been on a rollercoaster ride this past 2 weeks.
QLN tests are absolutely quite, except on the first resync, there was noise on the line, but that went on second resync.
I was looking at Skyeci post, looks the about same but ....... :-\
Any thoughts?
Have asked Plusnet if they can run a GEA test to see if anything stands out.
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ejs

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Re: Increasing Down snr increases line speed!
« Reply #1 on: May 19, 2017, 07:59:31 PM »

The differences between the two sets of stats look fairly ordinary and entirely to be expected.

The differences in attenuation will probably be due to different bands or frequencies being usable or not. Higher frequencies have higher attenuation, and the single attenuation figure will be some sort of average over all the bands.

The difference in max attainable rate is fairly minor and will depend on the current conditions, if there's less noise around, the max attainable rate will be higher.

The high current SNRM and low current speed will probably be due to there being more noise present at the time it connected, which has now gone.
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parkdale

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Re: Increasing Down snr increases line speed!
« Reply #2 on: May 20, 2017, 10:42:22 AM »

Thanks for the reply ejs. I got kicked off again last night:( speed went down to 25Mb/s DS was back at 20db But my snrm went up to 14db - 16db.
Ran a quite line test, nothing here but silence again.
I'm almost at the point of re-flashing my Fritzbox firmware back to previous version, all this seems to have started when it updated a couple of months ago, to see if it improves stability.
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WWWombat

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Re: Increasing Down snr increases line speed!
« Reply #3 on: May 20, 2017, 01:05:24 PM »

I'm not an expert in Fritzbox statistics, but the topic in the "subject" line doesn't seem to be borne out by the statistics: "Increasing Down snr increases line speed" doesn't seem to have happened.

The February statistics seem to say that the line was synchronised at approx 54Mbps down, 17Mbps up - numbers which match the "attainable" figures at the time, and backed up by having SNRM figures of 6dB.

The May statistics tell us that the line is synchronised very differently - 40Mbps down, 17.5Mbps up. That's a terrible drop in line speed, not an increase!
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burakkucat

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Re: Increasing Down snr increases line speed!
« Reply #4 on: May 20, 2017, 02:40:59 PM »

I wonder if there was visual "line slippage" whilst reading those GUI snapshots?

In February, the Line Attenuation was shown as 19 dB DS (receive) and 25 dB US (transmit).
In May, the Line Attenuation was shown as 24 dB DS (receive) and 29 dB US (transmit).

Could those "Line Attenuation" lines have been misread as the "SNRM" lines?

I'm very confused with the information provided . . .  ???
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parkdale

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Re: Increasing Down snr increases line speed!
« Reply #5 on: May 20, 2017, 05:45:48 PM »

Sorry to all, I ment to mean... the attainable has gone up.. whilst the line DS went up!
I thought that the higher the DS in db the lower the attainable would be :-[  (BB did go down to 25Mb/s then up to 30Mb/s on 2 resyncs)

Any how I got John Lewis(Plusnet) to run a GEA test and it's come back with a:-

I have ran a GEA test and following is the outcome:

Impairment in copper joint detected most likely in local network. Means there is a possibility of fault in your internal wiring or telephone socket (s).

Ok so i've poked and moved the cables around upto and after the master socket and I can't find hear any noise to indicate any breaks anywhere.

When the last OR man came round he replaced the line from the pole to house but not all of it... There's a join outside then another just inside the front door, then another section to the NTE5 box.

Edit to improve (sort of :-[) understanding of my dilemma.
« Last Edit: May 20, 2017, 06:04:29 PM by parkdale »
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Dray

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Re: Increasing Down snr increases line speed!
« Reply #6 on: May 20, 2017, 06:14:17 PM »

Max attainable isn't the same thing as Sync speed
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parkdale

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Re: Increasing Down snr increases line speed!
« Reply #7 on: May 20, 2017, 07:00:46 PM »

Sorry I mean that the Max attainable DS went up as my 'apparent length' of my line increased i.e. my line is 639 metres so @ 19db DS is giving me about 58Mb/s of max attainable speed of which about 50-54Mb/s is all I normally get. So 24db DS I thought would mean that my line has increased in length to about 807 metres, therefore my overall attainable should have dropped back to 45-48Mb/s , and give me about 40Mb/s speed at the router.
To get those speeds as attached.  i.e. someone moved my house nearer to the cab.
Hope this helps.
Sorry for my bad subject line.
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parkdale

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Re: Increasing Down snr increases line speed!
« Reply #8 on: June 01, 2017, 07:00:53 PM »

After a bit of a 20Mb rollercoaster ride on the download speeds... things seem to have settled down now.
While we were out  :( We had a visit by OR on Saturday, sods law  :-\ anyhow as you can see whatever he/she did the line now is on 6db margin constantly.
Still getting errors but at least the lines not getting reset every day :)
I have been doing BT Wholesale tests for my isp every day, one day says you are getting 52Mb/s this is the best/optimum speed for your line... another day it was you are getting 25Mb/s this is ....etc ???
Sorry for the poor quality of the available stats from my Fritzbox.
I see, according to UNO, my Fritzbox 3490 has made it onto the approved Sin list...

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