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| reply to BobTheVeg
Re: Need help/tips about DSL connection speed Hi again,
I revisited your inital post, i woke up and
thought maybe i could get thru once more...
When i align the numbers on a paper sheet,
these conclusions emerge: the attenuation
levels are both steady and so is the Remote/
UpStream SNR Margin which is a mere 6 dB. I
can observe both power levels fluctuate: on
the Local/UpStream side from 10.12 to 12.48
dBm, on the Remote/DownStream side from 7.63
to 8.63 dBm. Finally, the Local/DownStream
SNR Margin varies from 15.5 to 18 dB but we
see this happen quite often on DSL Reports.
Now, the "noise" curve says that your line
is suitably quiet except on some occasions.
The level of CRC Errors you're experiencing
is of no concern and it is normal to have so
few on an interleaved profile such as yours.
Well, there can be noise bursts but at the
moment this is what the curve leads to...
The UpStream SNR Margin, on the other hand,
is a major problem since there's no safety
margin left. I was hoping "Spectral Shaping"
would help here by allowing you to lower the
UpStream speed to something like 512, 384,
288 or even 256 Kbps - whatever it takes...
Unfortunately, the late 'DMT' capture appears
to indicate that your GNet BB0060B device is
not responding to tweaking the way mine does;
it's so puzzling i wonder if you saved this
configuration and rebooted (a cold power-up
boot, for example)... In any case, the final
objective is to make trade-offs relatively
to your UpStream signal as i just explained.
Lets suppose you managed to force this GNet
unit and its peer to negociate 2496/288 Kbps,
that doesn't mean you won't be able to find
a "sweet spot" where the UpStream SNR Margin
will be adequate/tolerable. Using "InterLeaved"
mode already, tweaking might buy you a raise
of profile but there's something wrong with
your attenuation levels: they tell me your
estimated "GNet distance" is shorter than my
own by five hundred meters and yet i'm on a
6016/512 Kbps Interleaving profile! So, it
seems to me it's likely because of a wiring
problem which Bell "fixed" by lowering your
profile instead of actually going after the
source of failure... I've thought of urban
cross-talk as the explanation but it would
not resurface like this just because one more
DSL neighbour arrived or switched to "Total"!
There are limits to what MoDem tweaking can
accomplish and trade-offs have to be made,
it's not going to resolve any phone line issues
magically but good trouble-shooting can help
you to understand the situation and then you
will be more persuasive when the time comes. | |
| 
Reduced speed |
I enabled the log each 10min and noticed that the Downstream SNRM has hit 20.0 over the day which I never seen before. As opposed to 11.5 from my first screen shot. | |
1 edit | Hi,
There's still a problem with the UpStream SNR Margin
so it would be hard to convince your ISP to ask Bell
for a profile raise, in my own opinion! If the decision
were mine, i know i'd have a hard time trying to put
in the balance the fact that you're on "Interleaved"
mode vs your relatively stronger DownStream signal.
The areas coloured in purple are those you must focus
for the time being, while the ones in red shall guide
you toward the goal to attain... 1st of all, call the
ISP and request that they capture the statistics from
Bell's "Line Test" portal in order to know what your
RCO numbers are with and without tweaks, additionally
to the attenuation levels. The other numbers coming
from the ISP's end would be nice to see as well. As
for the tweaking itself, once you have done this you
will find that there's no easy way to accomplish this:
it's a slow process during which you must try to learn
what value ranges are acceptable. Ideally, this must
be done one parameter at a time and then you can try
combinations later... For example, it's probable the
MoDem won't connect if you change all the numbers at
once using extreme values; lower 1 parameter slightly
(in steps) each time until you reach a limit beyond
which issues occur. Keep in mind that this limit may
very well move while other parameters are optimized,
meaning you better revisit previous limits when some
progress is made and then back off a bit to remain in
the stable operating range. The objective is to give
away some transmission power and hence related noise:
watch the UpStream "Tx Pwr" (Transmition Power) level
in hope that a few less dBm will translate as a few
more dB, with the UpStream SNR Margin but possibly
also the DownStream SNR Margin since less local noise
should leave more room for the DownStream signal too.
Euh... I made an error about the RCO in this graphic:
you should read "Enter Maximum Theoretical Speed based
on RCO"!... It may equally tell us what's a viable target.
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