Bitloading

[jezuk1]

Hi all,

I should point out this is entirely for interest purposes. I've noticed that a couple of tones are unused on my connection, there is no obvious reason as to why this is - i.e. the SNR ratio is normal. My only guess is that a few tones have been kept in reserve in case there is a burst of noise and a load of bitswapping required.

In this particular screenshot tones 95 (409.68 Khz, 2 bits) 100 (431.25 Khz, 0 bits) and 430 (1850.06 Khz, 0 bits) are the ones in question. I should point out on the previous sync last week the unused tones were different. Tone 211 (909.94 Khz) suffers from interference with the lower SNR ratio and bitloading (it's been like that for a while - must be something on that freq) but it's the unused tones that interest me more!

Any comments welcomed 

[Steve]

Have you read this article http://www.kitz.co.uk/adsl/adsl_technology.htm

[jezuk1]

I have done yep, a very useful website in general. None of these tones today fall into the category of "Tones which aren't in use." and I haven't read anything else that would explain why some tones are entirely unused. Perhaps I missed something 

[Rik]

It's possible that, at the time of syncing, those tones were 'noisy', and the router decided it was better to avoid them.