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:
Nov. 17, 1987
Filed:
Sep. 26, 1983
Carl F Andren, Indialantic, FL (US);
David A Olaker, Palm Bay, FL (US);
Harris Corporation, Melbourne, FL (US);
Abstract
In a spread spectrum communications system employing cyclic code shift keying as its primary modulation, the transmission waveform is spread for transmission security by modulo-2 adding a pseudo-noise sequence to the CCSK data symbols prior to phase modulating onto a carrier signal for transmission. If the transmission modulation is minimum shift keying (MSK) the two components of the data stream are applied to the carrier with a differential encoding step implicit in the modulation scheme. This differential encoding characteristic makes stripping of the PN spread function prior to CCSK demodulation difficult at the receiving end. In order to demodulate this waveform in an optimum manner, an array correlator, the adjacent correlator stages of which have one chip relative time displacements of their CCSK reference waveform, is employed. In effect the array correlator becomes a parallel array of matched filters matched to each cyclic shift of the incoming waveform. By modulo-2 addition of the PN spreading waveform with the time displaced CCSK reference waveform in each stage of the correlator, the correlator can be made to match all versions of the spread symbol being received.