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:
Aug. 09, 1983
Filed:
Feb. 20, 1981
Daniel D McRae, West Melbourne, FL (US);
Frank A Perkins, West Melbourne, FL (US);
Edward B Glover, Melbourne Beach, FL (US);
Harris Corporation, Cleveland, OH (US);
Abstract
Source intelligence within a predetermined bandwidth is normally provided to a transmission channel having a bandwidth constraint of the predetermined bandwidth. For privacy transmission, a first pulse train indicative of the source intelligence is derived and is enciphered by addition of pseudo-random values to the pulses, either directly or modulo some specified constant. The enciphered pulse train is converted to first and second symbol pulse trains at subharmonic frequencies of the first pulse train. Energy within a selected spectrum is derived from each symbol pulse train, such as by filtering, and used to modulate first and second channels of a quadrature modulator having a carrier frequency centered within the predetermined bandwidth. A suppressed carrier quadrature modulated output is transmitted along with a carrier frequency component. Receiving means include a quadrature demodulator and means for reconstructing symbol pulse trains and means for reconstructing an additively enciphered pulse train from symbol pulse trains. The enciphered pulse train is provided to an adaptive filter and deciphering means for provision of an output to an intelligence utilization means. A training mode of operation is also provided in which calibrating information is transmitted from enciphering means to the deciphering means. Weights of the adaptive filter may be adjusted during the training mode, and the adaptive filter is synchronized to sample each transmitted symbol several times.