coolbuddy_79
The Coolest One!!!
all the modulations are selected, that's multi-mode anyhow 
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MTNL Triband: Frequent Disconnections After 2mbps Upgrade?
- Thread starter amish
- Start date
- Replies 96
- Views 19,757
ashishgoel
Don
well SNR margin is goin to reduce as the line speed increases.What your modem shows is not the actual SNR but the SNR margin ie the difference between the actual SNR on the line and the SNR required to attain the speed allocated. As the speed increases from 256 to 2mbps the SNR required to sustain the speed increases but the actual line SNR remains the same, hence the drop in SNR margin.Currently MTNL is using the ITU g.992.1 standard also known as G.DMT so its advisable to disable all other modulations from the ADSL setting in the modem and select only g.dmt. Doing this should increase the SNR ratio. I have tried it and SNR has increased in my case.
smartbuddy_82
Regulars
me too changed the adsl setting to g.dmt...
Results:
1) Increase in my downstream data rate (from 2013 to 2048
2) SNR--- Downstream unchanged, upstream changed from 12 to 17
But Line Attenuation increased from 16 to 20 (downstream) and decreased from 34 to 10 (upstream)..
Any comments on this, @cyberwiz.... :huh:
Results:
1) Increase in my downstream data rate (from 2013 to 2048
2) SNR--- Downstream unchanged, upstream changed from 12 to 17
But Line Attenuation increased from 16 to 20 (downstream) and decreased from 34 to 10 (upstream)..
Any comments on this, @cyberwiz.... :huh:
QUOTE(yogi1771 @ Jan 12 2007, 07:18 PM) [snapback]74821[/snapback]
well changed the adsl setting to g.dmt,the result increase in my downstream data rate from 2013 to 2048 but decrease in my upstream rate frm 260 to 256 and my snr decreased frm 20 to 15
[/b]
Well its upto you, if u feel that changing the modulation doesnt work for u, u can always switch switch back. Though i think u are correctly synced now coz 2013 and 260 is not a profile that MTNL gives i.e. if ur modem sync's correctly then ur profile should be 2048 Downstream and 256 Upstream. And any SNR above 10 is adequate and reliable.
QUOTE(imranais @ Jan 12 2007, 09:33 PM) [snapback]74831[/snapback]
me too changed the adsl setting to g.dmt...
Results:
1) Increase in my downstream data rate (from 2013 to 2048
2) SNR--- Downstream unchanged, upstream changed from 12 to 17
But Line Attenuation increased from 16 to 20 (downstream) and decreased from 34 to 10 (upstream)..
Any comments on this, @cyberwiz.... :huh:[/b]
I think u have better stats now except that small drop in attenuation which shouldn't be a cause for worry coz its still pretty good.
well changed the adsl setting to g.dmt,the result increase in my downstream data rate from 2013 to 2048 but decrease in my upstream rate frm 260 to 256 and my snr decreased frm 20 to 15
[/b]Well its upto you, if u feel that changing the modulation doesnt work for u, u can always switch switch back. Though i think u are correctly synced now coz 2013 and 260 is not a profile that MTNL gives i.e. if ur modem sync's correctly then ur profile should be 2048 Downstream and 256 Upstream. And any SNR above 10 is adequate and reliable.
QUOTE(imranais @ Jan 12 2007, 09:33 PM) [snapback]74831[/snapback]
me too changed the adsl setting to g.dmt...
Results:
1) Increase in my downstream data rate (from 2013 to 2048
2) SNR--- Downstream unchanged, upstream changed from 12 to 17
But Line Attenuation increased from 16 to 20 (downstream) and decreased from 34 to 10 (upstream)..
Any comments on this, @cyberwiz.... :huh:[/b]
I think u have better stats now except that small drop in attenuation which shouldn't be a cause for worry coz its still pretty good.
ashishgoel
Don
QUOTE(cyberwiz @ Jan 12 2007, 06:54 PM) [snapback]74819[/snapback]
well SNR margin is goin to reduce as the line speed increases.
What your modem shows is not the actual SNR but the SNR margin ie the difference between the actual SNR on the line and the SNR required to attain the speed allocated. As the speed increases from 256 to 2mbps the SNR required to sustain the speed increases but the actual line SNR remains the same, hence the drop in SNR margin.
Currently MTNL is using the ITU g.992.1 standard also known as G.DMT so its advisable to disable all other modulations from the ADSL setting in the modem and select only g.dmt. Doing this should increase the SNR ratio. I have tried it and SNR has increased in my case.[/b]
well i'm using a different router, n in that either i can select one modulation or select it to - auto-sync...... it automatically chose - G.DMT and i even tried by selecting it - but still my SNR Margin - Down - 7 - 9 and Up - 9 - 11.... still on 256 kbps ... don't know what will happen if got upgarded??????????
well SNR margin is goin to reduce as the line speed increases.
What your modem shows is not the actual SNR but the SNR margin ie the difference between the actual SNR on the line and the SNR required to attain the speed allocated. As the speed increases from 256 to 2mbps the SNR required to sustain the speed increases but the actual line SNR remains the same, hence the drop in SNR margin.
Currently MTNL is using the ITU g.992.1 standard also known as G.DMT so its advisable to disable all other modulations from the ADSL setting in the modem and select only g.dmt. Doing this should increase the SNR ratio. I have tried it and SNR has increased in my case.[/b]
well i'm using a different router, n in that either i can select one modulation or select it to - auto-sync...... it automatically chose - G.DMT and i even tried by selecting it - but still my SNR Margin - Down - 7 - 9 and Up - 9 - 11.... still on 256 kbps ... don't know what will happen if got upgarded??????????
Ashish there are a lot of factors involved when we talk abt ADSL. Though u are quite near the lower limits of SNR margin, its not necessary that u will have an unreliable connection. In some cases SNR could be high but line attenuation also could be very high resulting in disconnections. In other cases line att could be high but SNR could be low leading to connectivity probs. Ur modem also plays an imp role some brands can hang to connections having SNR margin as low as 2 or 3, others might disconnect even at 7 or 8. So bottom line is that as long as it doesnt disconnect dont worry abt it.
QUOTE(cyberwiz @ Jan 12 2007, 06:54 PM) [snapback]74819[/snapback]
well SNR margin is goin to reduce as the line speed increases.
What your modem shows is not the actual SNR but the SNR margin ie the difference between the actual SNR on the line and the SNR required to attain the speed allocated.[/b]
SNR margin is NOT the difference as you said but its tolerance level.
How much decrease (difference) in SNR can be tolerated from exchange
to your modem. More the tolerance wud mean if noise is high it wud try
to re-correct the packets sent/received but that would mean speed will
decrease as same data is sent again. But then to achieve faster speeds
this tolerance should be decreased.
Noise here is not just noise created by voice but it cud be additional
disturbance caused in waves travelling through tel wire. Say by cable
TV wires, LAN cables etc. immitting signals and hindering tel signals,
inspite of insulation there still exists some disturbance.
Here is para from UT-Star modem help page:
"SNR Margin- Amount of increased noise that can be tolerated while maintaining the designed BER (bit error rate). The SNR Margin is set by Central Office DSLAM. If the SNR Margin is increased, bit error rate performance will improve, but the data rate will decrease. Conversely, if the SNR Margin is decreased, bit error rate performance will decrease, but the data rate will increase."
"Line Attenuation- Attenuation is the decrease in magnitude of the ADSL line signal between the transmitter (Central Office DSLAM) and the receiver (Client ADSL Modem), measured in dB. It is measured by calculating the difference in dB between the signal power level received at the Client ADSL modem and the reference signal power level transmitted from the Central Office DSLAM."
well SNR margin is goin to reduce as the line speed increases.
What your modem shows is not the actual SNR but the SNR margin ie the difference between the actual SNR on the line and the SNR required to attain the speed allocated.[/b]
SNR margin is NOT the difference as you said but its tolerance level.
How much decrease (difference) in SNR can be tolerated from exchange
to your modem. More the tolerance wud mean if noise is high it wud try
to re-correct the packets sent/received but that would mean speed will
decrease as same data is sent again. But then to achieve faster speeds
this tolerance should be decreased.
Noise here is not just noise created by voice but it cud be additional
disturbance caused in waves travelling through tel wire. Say by cable
TV wires, LAN cables etc. immitting signals and hindering tel signals,
inspite of insulation there still exists some disturbance.
Here is para from UT-Star modem help page:
"SNR Margin- Amount of increased noise that can be tolerated while maintaining the designed BER (bit error rate). The SNR Margin is set by Central Office DSLAM. If the SNR Margin is increased, bit error rate performance will improve, but the data rate will decrease. Conversely, if the SNR Margin is decreased, bit error rate performance will decrease, but the data rate will increase."
"Line Attenuation- Attenuation is the decrease in magnitude of the ADSL line signal between the transmitter (Central Office DSLAM) and the receiver (Client ADSL Modem), measured in dB. It is measured by calculating the difference in dB between the signal power level received at the Client ADSL modem and the reference signal power level transmitted from the Central Office DSLAM."
