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. 13, 1979
Filed:
Apr. 26, 1978
Lester R Querry, Laurel, MD (US);
Digital Communications Corporation, Gaithersburg, MD (US);
Abstract
A direction phase shift keyed communication system provides the capacity to transmit any one of two symbols for each modulation level. The modulator produces a substantially constant frequency signal which includes a phase transistion in respect of each information bit. In a system with a single modulation level, corresponding to a phase transistion .phi., one of the two symbols is represented by a phase transition +.phi., i.e., an advancing phase transition. The other symbol is represented by a phase transition -.phi., i.e., a retarding phase transition. A demodulator responds to a substantially constant frequency signal with a phase transition included, and produces an output signal of a first kind in response to an advancing phase transition +.phi. and an output signal of a second kind in response to a retarding phase transistion -.phi.. The system is capable of operating with multiple modulation levels, each of which can represent any one of two symbols, depending on the sense, i.e., advance or retad, of the transistion. Preferably, each modulation level is 180.degree. or a multiple thereof.