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Noise Margin & Data rate - Quick sanity check

FIXED
quinnaaa
Dabbler
Posts: 13
Registered: ‎31-07-2020

Noise Margin & Data rate - Quick sanity check

Hi All, 

Just looking at the stats on the router and wondered why the upload noise would be so much more than the download?
Also the data rate vs max data rate.  Losing around 10Mbps is that expected?

Data rate: 19999 / 76344
7. Maximum data rate: 27481 / 86759
8. Noise margin: 15.2 / 6.7
9. Line attenuation: 13.9 / 13.1
10. Signal attenuation: 13.6 / 13.1


As a side note, the exchange is less than 40 meters away. Although it might bounce around a few cabs to get there. 

Thanks

3 REPLIES 3
MisterW
Superuser
Superuser
Posts: 14,575
Thanks: 5,411
Fixes: 385
Registered: ‎30-07-2007

Re: Noise Margin & Data rate - Quick sanity check

Fix

Noise margin (snr) is the difference between the level of signal and the level of noise. Since noise tends to increase as speeds increase, a line syncronise at the fastest speed it can whilst maintaining a noise margin of about 6db ( the target snr )

However, there arel imits to the sync speeds, on the Fibre extra it is 80Mbdown and 20Mb up.

Your line is capable of higher speeds but the limit of 20Mb up, means that the line can achieve that easily and so the snr is higher I.e more headroom. In this case a higher snr is good Asiatic will mean less errors

Superusers are not staff, but they do have a direct line of communication into the business in order to raise issues, concerns and feedback from the community.

PeeGee
Pro
Posts: 1,217
Thanks: 84
Fixes: 3
Registered: ‎05-04-2009

Re: Noise Margin & Data rate - Quick sanity check

Firstly, the max data rate is a figment of the router's imagination! Basically it is what some algorithm suggests you may be able to get if you have a connexion above 80Mbps/10Mbps based on line parameters.

Secondly the lower frequencies used for upload are generally more tolerant of noise, so the margin is higher.

Plusnet FTTC (Sep 2014), Essentials (Feb 2013); ADSL (Apr 2009); Customer since Jan 2004 (on 28kb dial-up)
Using a TP-Link Archer VR600 modem-router.
198kHz
Seasoned Hero
Posts: 5,730
Thanks: 2,773
Fixes: 41
Registered: ‎30-07-2008

Re: Noise Margin & Data rate - Quick sanity check

I believe @MisterW 's explanation to be more accurate.

Murphy was an optimist
Zen FTTC 40/10 + Digital Voice   FRITZ!Box 7530
BT technician (Retired)