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:
Apr. 06, 1976
Filed:
Oct. 21, 1974
Gerhard Wagner, Schaftlach, DT;
Otto Albersdoerfer, Munich, DT;
Siemens Aktiengesellschaft, Berlin & Munich, DT;
Abstract
Identification -- friend or foe systems which utilize computer control continuously changing interrogation signals and responding signals have been developed. The signals are varied in a time dependent manner, however, it is possible that an intruder might intercept a proper responding signal and repeat the code of this responding signal, and thus confuse the interrogating station. The present system allows a responding signal to be used only once during a particular time interval so that an interrogating station will know that if an otherwise proper responding signal is received twice during a time interval, that the second signal is spurious.