I am on 21CN ADSL1 - at my request and these are my stats
Noise Margin: 4.6 dB (default is 6dB)
Connection Rate: 5024 Kbps
Line Attenuation: 50.0 dB
The reason it drops from 6dB to 4.6dB is that the higher tones drop out in the evening and don't re-establish.
Looking at the graph of frequencies actually used there is virtually nothing above 800kHz and even immediately after a resync the bit loading over 840kHz is very low

And the 3dB difference is a doubling of actual attenuation, because twice the number of frequency bins are involved.

Once you plot the bins out for a line, particularly the marginal ones at the ADSL2/ADSL2+ cross over it is obvious

Is that how the actual calculation is done.
Although ADSL2+ goes up to 2,200kHz I would be surprised if the attenuation calculation rates all those bins equally.
I suspect it depends on the router calculation algorithm and whether the tones used are the theoretical maximum or the actual tones in use.
http://wiki.kitz.co.uk/index.php?title=Attenuation_i...

The averaging is probably weighted according to how many bits are allocated to each tone, so the calculation is fairly complex, and different modem/routers can use different algorithms for making the calculation.

Thanks for the ongoing feedback but sadly some of it is now going over my head

I took a screen grab of the Routerstats bit tone graphing and here is the link (sorry file size is bigger than intended but did not want to lose viewable details by reducing the colours too much.

http://1stdesignit.co.uk/random/bit_tone_page.bmp

So, any added insigt of what this tells you & me would be welcome.

As noted above here again is the copied info about the conection itself

Channel: FAST, Upstream rate = 443 Kbps, Downstream rate = 3147 Kbps
Link Power State: L0
Mode: ADSL2
Channel: Fast
Trellis: U:ON /D:ON
Line Status: No Defect
Training Status: Showtime
Down Up
SNR (dB): 6.3 18.8
Attn(dB): 54.5 28.7
Pwr(dBm): 0.0 13.1
Max(Kbps): 4020 828
Rate (Kbps): 3147 443

Many thanks again in advance

In reply to a post by adamtemp:

In my own case the differance between the additional atten from 2+ can be seen daily. now on a wbc connection via madasafish (plusnet)

At night on the 3db target snr router resyncs to adsl2 with a atten of 48.8 sync aound 4443
Reset after 8am I get 3db target snr router resyncs to ADSL2+ with atten of 52.1 sync around 5318 depending on local noise.

Previously to wbc on max I was on atten around 48 and sync around 4200 most of the time.with a 9db target snr see thread here http://forums.thinkbroadband.com/freenetname/f/40840...

Hope that helps

Hi

Very intertesting that your "Max Rate" is equal to "Your Current Rate" whereas mine is not thought granted my attenutaion is higher???

Which is what I would expect - maximum frequency in use is about 750kHz so ADSL2+ would have no advantage over ADSL2.
In fact, other than the slightly better algorithm, ADSL1 would give similar results
You do realise that you have also posted your IP address in the image

Hi Oldjim

Thanks for the insight..............I surmise that is why the training period defaulted it back to ADLS2 flavour not 2+

It does seem that I am getting quite close to ADSL Max figures though (I will post to discuss/share later) I was getting a small but welcome improvement in sync and measured speed until a few days ago!

PS thanks for the heads up ~ now cropped and re-uploaded Hopefully no harm done???