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:
Sep. 29, 1981
Filed:
Jun. 29, 1979
Frank de Jager, Eindhoven, NL;
Rudolf A Van Doorn, Eindhoven, NL;
Johannes J Verboom, Eindhoven, NL;
Marino G Carasso, Eindhoven, NL;
U.S. Philips Corporation, New York, NY (US);
Abstract
The invention relates to a method of demodulating a quadphase coded data signal and a receiver for carrying out the method. The quadphase code comprises four elementary wave forms, each wave form representing two bits of the original non-coded binary signal. An elementary wave form consists of four half bit intervals, the signal corresponding to the first and the second bit, respectively, being transmitted in the first and the second half bit interval and the signal corresponding to the inverted value of the first and the second bit, respectively, being transmitted in the third and the fourth half bit interval. In a receiver according to the invention such a signal is sampled in each of the four half bit intervals. In principle all information is already available after the sampling operations in the first and the second half bit interval, but by utilizing all four samples a proper protection from noise, interference and zero level shifts is obtained. The receiver determines the difference of the samples taken in the first and the third half bit interval and the difference of the samples taken in the second and the fourth bit interval. A positive difference represents a logic 1, a negative difference a logic 0.