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:
Jul. 06, 1982
Filed:
Jul. 30, 1980
Smith A Rhodes, Falls Church, VA (US);
Communications Satelite Corp., Washington, DC (US);
Abstract
A Frequency Shift Offset Quadrature (FSOQ) signal which is a constant envelope frequency-shift keyed version of an offset quaternary phase shift keyed (O-QPSK) transmission is provided. A technique for generating an FSOQ signal in a manner similar to O-QPSK by modulating offset quadrature channels with selectable pulse shapes which yields the desired 3-tone continuous phase FSK approximation of O-QPSK is disclosed. Receiver synchronization circuits are also provided which enable FSOQ to be detected as a special case of O-QPSK, whereby the detection performance of synchronous coherent QPSK, rather than the relatively inferior performance of FSK detection, is obtained. FSOQ provides a constant envelope and requires less bandwidth than minimum shift keying (MSK).