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:
Mar. 22, 1977
Filed:
Jan. 29, 1975
Kenneth M Branscome, Dallas, TX (US);
William M Feath, Irving, TX (US);
George E Goode, Richardson, TX (US);
Kenneth W Heizer, Dallas, TX (US);
Barrie O Morgan, Dallas, TX (US);
Datotek, Inc., Dallas, TX (US);
Abstract
The specification discloses a voice scrambler technique wherein a voice signal is split into a plurality of discrete frequency sub-bands. A random code generator generates a randomized sequence of digital signals. A preselected first portion of each of the digital signals is utilized to control the rearrangement of the order of the frequency sub-bands according to a limited subset of all possible combinations of rearrangements of the frequency sub-bands. The limited subset is chosen to include only the most unintelligible of the possible combinations of rearrangements of the frequency sub-bands. A preselected second portion of each of the digital signals is utilized to control the random inversion of ones of the frequency sub-bands. The rearranged and inverted frequency sub-bands are then transmitted over a conventional voice communication line to a similar voice scrambler unit which operates in synchronism to rearrange and invert the frequency sub-bands to the original state in order to render the voice signal intelligible. The system includes a unique synchronism technique which automatically compensates for time delays in transmission and which allows tolerance of transmission errors. The system includes an alarm function which becomes operative upon the occurrence of a malfunction and also includes various other safety devices to prevent the transmission of uncoded voice data in case of a malfunction of the system.