SNR Values incorrect

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ThatOtherGuy

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Hi,

I logged a call with SAOL coz my speeds have degraded in the last 2 days(even though it wasn't like some of you guys reported, even before this.) Anyway, they told me that they tested the line and found that the SNR values are not correct and they have logged a call with Telkom who will contact me(hopefully soon).

What are SNR values and how does it affect speed? If it is corrected, will it improve my speeds? How is it resolved(and will it cost me?) Does SNR have anything to do with my router, will getting a better router improve it?

Sorry about all the questions. :o
 
SNR = signal-to-noise ratio.

The more noise the worse the Speed. Telkom will look into the problem but there is not much they can do. If its really bad they might replace something and get the noise level down a little.

There would be no cost from your side.

If you pick up your phone, do you hear crackling ?
 
Noise Margin (AKA Signal to Noise Margin or Signal to Noise Ratio)
Relative strength of the DSL signal to Noise ratio. The higher the number the better for this measurement. In some instances interleaving can help raise the noise margin to an acceptable level.

6dB or below is bad and will experience no-synch or intermittent synch problems
7dB-10dB is fair but does not leave much room for variances in conditions
11dB-20dB is good with little or no synch problems* (but see note below)
20dB-28dB is excellent
29dB or above is outstanding

* Note that there may be short term bursts of noise that may drop the margin, but due to the sampling time of the management utility in your modem, will not show up in the figures.

Line Attenuation
Measure of how much the signal has degraded between the DSLAM and the modem. This is largely a function of the distance from the exchange. The lower the dB the better for this measurement.

20dB and below is outstanding
20dB-30dB is excellent
30dB-40dB is very good
40dB-50dB is good
50dB-60dB is poor and may experience connectivity issues
60dB or above is bad and will experience connectivity issues
 
ThatOtherGuy said:
Hi,

I logged a call with SAOL coz my speeds have degraded in the last 2 days(even though it wasn't like some of you guys reported, even before this.) Anyway, they told me that they tested the line and found that the SNR values are not correct and they have logged a call with Telkom who will contact me(hopefully soon).

What are SNR values and how does it affect speed? If it is corrected, will it improve my speeds? How is it resolved(and will it cost me?) Does SNR have anything to do with my router, will getting a better router improve it?

Sorry about all the questions. :o
Click to expand...

Telkom will just say it's within acceptable limits, your best hope, and I know it sounds stupid, is that you have a lot of noise (crackling, static) on your voice line, because then they have to sort that out and in most cases it will resolve your problem with the ADSL as well.
 
The lightning destroyed my modem and phone line over the weekend. Telkom responded quickly and repaired the line on Monday. Problem is that I now have a line attenuation of 54 and Telkom refuse to anything about it, as the ADSL 'synchs'.

They categorically state that the upper limit is 55, my line is within that limit. Line is fine for surfing, mail and the like....just don't play WoW or torrent!

Thinking of hooking up a welder to the twisted pair and frying their exchange...or casually driving past the Telkom box and setting it alight.
 
Scoliosis said:
Problem is that I now have a line attenuation of 54 and Telkom refuse to anything about it, as the ADSL 'synchs'.
Click to expand...
Probably reconnected your line via longer route (basically attn = distance). I'm in the same boat, attn = 57-60db on a 512K line and Telkom recon there's no other copper/route.

Only advice I can give is get yourself an ADSL modem/router that uses the Broadcom BCM63XX chipset which is infamous for handling long/crappy lines the best. My primary router is a fancy Cisco 877W, but I rather connect it to a cheap modem with the BCM chipset instead of the Cisco's built-in modem as the performance drills the Cisco's STMI (Alcatel) chipset.

Two cheapy (~R250) BCM based ADSL modems/routers readily avaliable on the market are;

D-Link DSL-2500U
TP-Link TD-8840 (one I use)

NB: Your performance may vary as Telkom uses different makes of DSLAMs each with a different chipset.
 
I don't particularly remember a scratchy sound on the phone, but then again I don't use the phone. Anyway, I'll have to see what telkom says. I'm not sure what my SNR and attenuation is though. I'll see if I can see anything in my modem's config when I get home.
 
Signal-to-noise ratio is NOT the same as the noise margin. The noise margin tells you how far above the REQUIRED signal-to-noise ratio you are, to sync at a particular speed.
 
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