The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jun. 17, 1997
Filed:
Jul. 19, 1994
Saulius Janusas, Seacliff, NY (US);
Grumman Aerospace Corporation, Los Angeles, CA (US);
Abstract
A covert communication system utilizes a series of low level duty cycle coded pulse train transmissions which at the necessary end have signal to noise ratios much smaller than unity. Such transmissions are buried in noise and hence are undetectable by ordinary means. The coded pulse trains do not carry data and their sole purpose is only to be compressed by a code matched correlator into a single large pulse per pulse train. Data are encoded in the timing between adjacent compressed pulses of adjacent pulse trains. The low duty cycle of the pulse trains is used to force an unfriendly receiver, which does not know the code of the pulse train transmissions, to integrate its own receiver noise into its detection circuits, thus making the transmissions even less detectable.