bz wrote:

> "Sebastian G." <seppi@seppig.de> wrote in
> news:62qjtgF2484t3U3@mid.dfncis.de:
>
>> bealoid wrote:
>>
>>> "Sebastian G." <seppi@seppig.de> wrote in
>>> news:62q4cpF2486s5U1@mid.dfncis.de:
>>>
>>> [snip]
>>>
>>>> This is nothing special though, even Peter Gutmann mentions much more
>>>> potent ways like magnetic force scanning tunneling microscopy.
>>> and even gutmann says that no longer works and that 3 random overwrites
>>> is about as good as you can do.
>>
>> And even I wrote that one overwrite is enough, but this doesn't change
>> the result that such techniques allow to retrieve information
>> statistically significantly better than random guessing. If the high
>> level data are encoded with redundancy as well, this might be a problem.
>
> remember that you are allowed as many read passes as you want on each
> track. This allows 'averaging out' much of the noise.


I doesn't average out the noise that is itself part of the recorder signal
on the media, which is the main reason why this technique isn't effective
any more.