Johnatan56
Honorary Master
41 is about 11Mbps, 43 hits about 9, but it depends a lot on copper quality.
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Understanding SNR and Attenuation Rates
- Thread starter Mineer
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41 is about 11Mbps, 43 hits about 9, but it depends a lot on copper quality.
Mephisto_Helix
Resident Postwhore
Another question for you guys - second day in a row now that my SNR has dropped from it's 8.5 - 9.0 to like 4.2 and all internet goes dead AND round about the same time ..... wth is up with that?
Johnatan56
Honorary Master
Line fault. Gl.
Mephisto_Helix
Resident Postwhore
hey, line fault gives me hope of a resolution, I'll take it!
Lol
Lol
Very stable this side lately, Touch wood.
Code:
Broadband Connection
2.1TypeADSL2+ Annex A
2.2StatusUp
2.3Uptime9 days 3 hours 39 mins 11 secs
2.4Line Rate (Down / Up)12476 kbps / 1022 kbps
2.5Noise Margin (Down / Up)6.7 dB / 7.8 dB
2.6Attenuation (Down / Up)24 dB / 14.1 dB
2.7Power (Down / Up)18.2 dBm / 12.1 dBmJohnatan56
Honorary Master
Very low SNR for that Attenuation+ speed.
Yup, but somehow works.
beesboertjie
Senior Member
With ADSL one can deduce the length of your copper wire directly from your router’s attenuation. I compiled this graph.
Attenuation is the reduction in signal strength on your telephone line. The experts say attenuation is normally directly proportional to the length of your line.
1,0 km = 13,8 dB
1,5 km = 20,7 dB
2,0 km = 27,6 dB
2,5 km = 34,5 dB
3,0 km = 41,4 dB
3,5 km = 48,3 dB
4,0 km = 56,0 dB
4,5 km = 62,1 dB
5,0 km = 69,0 dB
> 5,0 km (sorry mate)
My router says my attenuation is 11 dB. According to this table I’m 800 metres from the exchange. That’s very likely. I have a 4 mbps ADSL line, my actual speed is 3,4 mbps.
beesboertjie
Senior Member
This graph shows how the speed of VDSL2 drops with copper wire, from a VDSL2 street-side cabinet, to your house.
The electrical signals run out of steam very quickly. If you happen to live close to one of these street-side cabinets, you’ll get download speeds of around 80 mbps. But notice how quickly the speed reduces, 1 km out and the speed has dropped to 30 mbps.
Windsor Castle is slightly north from The Home Park Golf Course. Queen Elizabeth might have 10 mbps internet.
With optical fiber distance does not matter, speeds remain constant.
https://neil-fairbrother.squarespace.com/blog/2013/7/1/gfast-a-high-speed-cul-de-sac
TypeADSL2+ Annex A
2.2StatusUp
2.3Uptime3 days 6 hours 36 mins 47 secs
2.4Line Rate (Down / Up)12476 kbps / 1022 kbps
2.5Noise Margin (Down / Up)6.5 dB / 7.5 dB
2.6Attenuation (Down / Up)24 dB / 14.1 dB
2.7Power (Down / Up)18.3 dBm / 12 dBm
Tx. Just over 1 km for me..
beesboertjie
Senior Member
Hi BigBear, taking your Down Attenuation of 24 dB, the length of your copper wire is 1,7 km.
Please test your line speed with the Ookla speedtest. At 1,7 km your ADSL should already be slower.
Click here for your desktop PC or laptop computer http://www.speedtest.net/
For your smartphone on Wi-Fi through your ADSL router http://www.speedtest.net/mobile/
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Johnatan56
Honorary Master
Attenuation has nothing to do with speed past the max speed you can sync at. A 4Mbps DSL line will hit ~3.6Mbps after overheads if it's 100m from the exchange or 3km.
The difference in latency is negligible, shouldn't even be 1ms.
Geoff.D
Honorary Master
The distance from the node manifest itself as a line attenuation which in turn only determines whether the modem locks onto the signal at a level that will not be affected by too high noise levels. After that, service performance is entirely determined by the service setup. And that is where the problem usually lies. Especially when the ISP or service provider now provides you with a service according to the LCD principal.
Current busy streaming etc
http://www.speedtest.net/my-result/i/2187941270
Best and usually get around these numbers
http://www.speedtest.net/my-result/i/2172085070
beesboertjie
Senior Member
Wow!
Johnatan56
Honorary Master
Wow what? That his is so much higher?
I am at the edge of what my max sync is, 40dB Attenuation (Though I have 10Mbps sync, so max out at ~8.6Mbps).
beesboertjie
Senior Member
Hi Johnatan56, I’m saying Wow! because you’re both fast, compared to my 3,4 mbps. More than twice two-times double my speed. Your PING is almost as fast as Wayde van Niekerk.
With 40 dB attenuation, the length of your copper wire is 2,9 km.
With 40 dB attenuation, the length of your copper wire is 2,9 km.
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beesboertjie
Senior Member
Hi Johnatan56, I’m just checking out the validity of the graph. The graph seems to be reliable, assuming that you and BigBear are both on 10 mbps ADSL lines.
Johnatan56
Honorary Master
Hi, I am on ADSL2+, my sync is 10Mbps with a max of 13Mbps.
You can't graph the speedtest as that does not include overheads (which account between 15-20% on ADSL, 10-15% on VDSL, 5-10% on fiber though fiber is usually set to burst to make up for it.).
BigBear is probably on 10Mbps with interleave, Telkom set it so that if one is on interleave you'd sync at 12Mbps to help with packet correction. 4Mbps syncs 5Mbps, 8Mbps syncs about 10Mbps.
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beesboertjie
Senior Member
Hi Johnatan56, thank you for your expertise. I’ve adjusted your speedtest of 7,83 mbps by 15% and by 20% to include the overheads. The graph now seems good to me, it clearly shows that you’re on ADSL2+ and your overheads are 20%. Don’t you also think this is spot-on? I hope so.
7,83 mbps / 0,85 = 9,21 mbps and 7,83 mbps / 0,80 = 9,79 mbps
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