Re: detecting keystokes via satellite

From: Jan Panteltje (pNaonStpealmtje_at_yahoo.com)
Date: 07/07/05 

Date: Thu, 07 Jul 2005 13:36:13 GMT

On a sunny day (7 Jul 2005 12:35:58 GMT) it happened n05W27+mgk25@cl.cam.ac.uk
(Markus Kuhn) wrote in <daj7je$d92$2@gemini.csx.cam.ac.uk>:

>
>
>"Nathan Gant" <NGANT17@peoplepc.com> writes:
>|> Is it possible for overhead satellites to detect the infrared or Van Eyk
>|> signature of the keystrokes coming from a typical PC?
>
>The paper
>
> http://www.cl.cam.ac.uk/~mgk25/ieee02-optical.pdf
>
>explains (in section 6.3) how you can calculate a theoretical upper
>limit (due to shot noise) for the range at which a passive
>eavesdropping attack on an IR channel works. You just need
>to plug in some numbers for your particular scenario
>(in particular: bit rate, transmitter luminosity, background
>luminosity within the receiver band).
>
>Markus
Is that the best picture in that pdf that you got?
There is still a significant error (smear) in the LF range.
Line based clamp (DC component restor) + perhaps some LF compensation
would further improve things?
This sort of LF error can be compensated a lot by RC filters.