VDSL SNR margin and line attenuation

[Derina]

Hi everyone I have a question that I couldn’t find the answer to it
I have a VDSL connection. The modem shows that current speed is at 80mbit download but I can never even get close to it and there are so many packet errors and max SNR margin is at 7. After sometime using the net the SNR margin even gets lower to near 3 and sooo many error packets.
Line attenuation is good like 13.5 and lower but SNR is so bad.
How can I fix that? Does changing copper wires all along help with this? cause line attenuation is great but snr is terrible or it will not help at all?

[Dujith]

VDSL / ADSL is very much dependent on 2 things (more but these 2 dictate most)

1. Distance from the distribution point, the father you are away the worse it will be. 
2. Interference, the list of things that interfere with DSL is long and things in that list are in most all houses. 

(1) Distance is something you have no influence on. The extra length in your house is not the issue, the way it acts like an antenna in your house does however.

(2) Interference is something you can deal with, The cable from the telecom provider is most likely shielded up until your house.

The moment that stops any extra length will start to pick up interference. So either: use shielded cable to your modem or keep your modem as close to the telecom provider as close as possible.

 

[Derina]

1 hour ago, Dujith said:

VDSL / ADSL is very much dependent on 2 things (more but these 2 dictate most)

1. Distance from the distribution point, the father you are away the worse it will be. 
2. Interference, the list of things that interfere with DSL is long and things in that list are in most all houses. 

(1) Distance is something you have no influence on. The extra length in your house is not the issue, the way it acts like an antenna in your house does however.

(2) Interference is something you can deal with, The cable from the telecom provider is most likely shielded up until your house.

The moment that stops any extra length will start to pick up interference. So either: use shielded cable to your modem or keep your modem as close to the telecom provider as close as possible.

 

My main confusion is that how can line attenuation be very good but snr margin so bad. If noise was the case my line attenuation would also go up right?

[Dujith]

Line attenuation is not SNR, Line attenuation is related to your distance from the distribution point.

It means how much of the signal was lost while traveling to your house. It however says nothing about how noisy the signal is.

 

Thats why you have SNR it will tell how how much signal there is vs noise.

As a simple explanation: Lets say we are standing 50 meter apart and we are talking to each other. In a silent room that would be no problem.

But lets say someone is drilling in between us: i'll need to shout now and maybe repeat thing.

What u hear over the drill is the SNR. Its the effective signal that can be used.

Anything below 10dB will cause issues.

 

Best bet is placing the modem next to the provider point and test there. If there is still a bad SNR then call your provider.

If its good, see if you can leave it there and work with network cables from there to switches and such.

 

[Derina]

2 minutes ago, Dujith said:

Line attenuation is not SNR, Line attenuation is related to your distance from the distribution point.

It means how much of the signal was lost while traveling to your house. It however says nothing about how noisy the signal is.

 

Thats why you have SNR it will tell how how much signal there is vs noise.

As a simple explanation: Lets say we are standing 50 meter apart and we are talking to each other. In a silent room that would be no problem.

But lets say someone is drilling in between us: i'll need to shout now and maybe repeat thing.

What u hear over the drill is the SNR. Its the effective signal that can be used.

Anything below 10dB will cause issues.

 

Best bet is placing the modem next to the provider point and test there. If there is still a bad SNR then call your provider.

If its good, see if you can leave it there and work with network cables from there to switches and such.

 

Ok thank you so much for your help and explanation.

I have had tested where provider point is but the SNR is about the same but there is no to little packet errors and more speeds

[Dujith]

1 minute ago, Derina said:

Ok thank you so much for your help and explanation.

I have had tested where provider point is but the SNR is about the same but there is no to little packet errors and more speeds

Every dB matters when you are talking about SNR. If its 7 there then call your ISP and let tem send a tech.

[Derina]

13 hours ago, Dujith said:

Every dB matters when you are talking about SNR. If its 7 there then call your ISP and let tem send a tech.

It is about 8 in ISP point in our alley but around 6 to 7 in ground floor. Then when it comes up to my apartment on 5th floor the snr is about the same but speeds drop.

It is 15 meters from alley ISP point to my ground floor. Is there any real problem or it is normal for those drops along the way?