The NSA STM method is related to reading _very subtle_ variations in magnetic domain modifications. Jitter in read-write head positions can be thought of as a noise (N) added to some signal (S)l.

Extraction of signals in low S/N ration environments is a well-developed science.

As anyone who has ever subscribed to alt.sex will know ;-) Datacomms Technologies web authoring and data security Paul Bradley, Paul@fatmans.demon.co.uk Http://www.fatmans.demon.co.uk/crypt/ "Don`t forget to mount a scratch monkey" -----BEGIN PGP PUBLIC KEY BLOCK----- Version: 2.6 mQCNAjH9j+cAAAEEAMBvREiQR0ot9dFCO0TiSCSunAYLv2g1Bc6I3bz8FzKXNH53 6mieJf/W4rD+CxJpT0q9RQaaoRtkHJLwbjfK2il3D7mEahMAyqvF/xRJNqkXfhM3 sRJM0Jh43l+W0M5vwokbEbk25/bxWWGspTsLD3YHbzKnG6pOcL5OPIRbv66xAAUR tCdQYXVsIEJyYWRsZXkgPHBhdWxAZmF0bWFucy5kZW1vbi5jby51az4= =riHc -----END PGP PUBLIC KEY BLOCK-----