Thread: SNR Margin and Line Attenuation - What do they mean?

Originally Posted by mansawy

tell me this's good or not

I thought you will be attentive enough to check the previous post to your thread. It is explained here




Attenuation is high.Which normally happens when your location is a bit far from exchange.

Reproduced from thread UDAAN.
LINK back: http://www.indiabroadband.net/bsnl-b...tml#post330317 (BSNL udaan no response)
By @whitestar_999

@meetdilip,i hope you won't mind me correcting some of the common myths surrounding SNR & Line attenuation values here & since you are a frequent & reputed poster i am hoping you will spread this.

first of all simply saying high SNR value in any situation is good is incorrect.besides line condition SNR value also heavily depends on the rate at which your modem syncs with the DSLAM in exchange.that is why in many european countries/usa where people use 16-24mbps plans their snr values are usually 10-15.in india most bsnl users syncs at ~2mbps so here snr ~30 or more can be considered as good but if & when user start syncing at 8mbps or higher this does not hold true.

Quote:
from a known australian broadband forum:

Dont understand why people are saying that a snr over 30 is good when i can download at 2.35mb/sec and my snr is well and truely below 30
Sync speed down 23500 up 1000
snr down 4.5db up 9db
att down 8.5db up 6.5db
also the chart you used for attn values is not correct.again from the same forum as mentioned above:
attn values & expected speeds
Fremnet.net
1.0km = 13.81dB = 23Mbit
1.5km = 20.7dB = 21Mbit
2.0km = 27.6dB = 18Mbit
2.5km = 34.5dB = 13Mbit
3.0km = 41.4dB = 8Mbit
3.5km = 48.3dB = 6Mbit
4.0km = 56dB = 4Mbit
4.5km = 62.1dB = 3Mbit
5.0km = 69dB = 2Mbit

my downstream attn is 42 & i get usual ~1.8mbps speed on 500C plan while modem reports max attainable rate as 8mbps.one more important thing to keep in mind is that different modems report different SNR & attn values because of the difference in their calculating method.my nokia c2110 modem reports attn as 36 while my TP-LINK modem reports downstream attn as 42 on same line.

@meetdilip
try this tool for finding distance to Exchange and theoretical speed.
( Note KBits)

Fremnet.net

Here



Exchange is about 300 m from my home.

@meetdilip

Since we have Home 750 plan max 512 Kbps speed ,
again verify the sync rate/rate as shown in different
modems with different mod modes.

Instead of groping in the dark, applications and data like these
help non tech users like me to try something to improve speed,
short of selling present house and buying a new house near the exchange !!
for best ATTN SNR figures and good speed!!

SNR is a bit low. Do you hear hissing sound on your land line ? Talk to the line man. Ask him to give a clean line. Make sure there are no joints or non insulated parts. It is better handled as line man level. If still no change, talk to the SDE.

This may help

http://www.indiabroadband.net/broadb...ubleshoot.html (Frequent Disconnection : Steps to troubleshoot)

SNR Margin (dB): 7.7 (Downstream) 13.8 (upstream)
Attenuation (dB): 51.0 ((Downstream)) 32.4 (upstream)
Output Power (dBm): 12.9 ((Downstream)) 0.0 (upstream)
Attainable Rate (Kbps): 5300((Downstream)) 876 (upstream)
Rate (Kbps): 2044((Downstream)) 874 (upstream)

What does this rating shows???
i am having frequent dsl break.....doi need a line change???

If you post in an old thread , it is presumed you have read all the posts!
then the query will not be there !
see Post no 151.
check with
http://fremnet.net/article/216/adsl-...eed-calculator
Post with details of modem number in your Isp's forum as a NEW thread.

My specifications are


SNR Margin (dB): 3.7 5.7
Attenuation (dB): 53.0 35.8
Output Power (dBm): 12.9 0.0

With this I was getting download speed (uTorrent and also shown by bandwidthmeter) approx 190 kB/s. But then now i get only 25-30 kBps and often (for 10-15mins the full speed).So i called the lineman.He came,sees the line and after that no improvement in speed although there is no noise in my telephone.
Please help.

Try port forwarding. Or switch to bridge mode. All ports are open by default.

This may help

http://www.indiabroadband.net/broadb...onnection.html (How to: get max. speed of a connection)

Originally Posted by Rameshjeee

From the junction box,the telephone wire directly runs to my house. Its a new wire,I got it changed recently.
I dont have any paralled connection.
But still the SNR value is around 7~8.
Attn Value is around 40~45.
I do experience frequent disconnection for 10 sec...
When the connection is there...I get the expected speed & I dont face any issues.

According to just4kix Chart, I have the following.
SNR value is around 7/Downstream ~ 6/Upstream.
Attn Value is around 41/Downstream ~ 22/Upstream.


Looking at the table My SNR = Fair but does not leave much room for variances in conditions.
Line Attenuation = Good,

Fair + good doesn’t sound that promising really. I never really looked into the numbers before until today, I get good speeds. Speed test around 10.5mbps, upload speeds is crap of course.

In my mind I thought well connection running good, maybe a few drop outs from time to time other than that I assumed everything is in order But? When you look at the facts things look different on this side of the fence so to speak.

Would be nice to see, this kind of numbers Right.

SNR
1. 20dB-28dB. = Excellent
2. 29dB. or above = Outstanding

Line Attenuation
1. 20bB. and below = Outstanding
2. 20dB-30dB. = Excellent


I think all of us who has read this thread will think the same Yes, So how do we improve the numbers on the router is it a router issue, is it a ISP issue, or just the line itself, what can we do ourselves to make it better, any thoughts or suggestions.


Twisted.

If you are in Australia , the ISP may be contacted.
Mention adslmodem/make/number.

I feel SNR is a bit low and Attenuation a bit high. Get you line fixed. Make sure there are no joints, non insulated / non oxidised parts. Inspect manually and make sure that the line is clean.



This chart may be a bit inaccurate for speed above 8 Mbps.

What do my stats say here?
Why Output Power is so low here. Sometimes its negative !!

Update from @amasoun after trying different mod modes.
http://www.indiabroadband.net/bsnl-b...tml#post343180 (Changing DNS BSNL Punjab)