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. 30, 1986
Filed:
Jul. 22, 1985
Yukinobu Ishigaki, Tokyo, JP;
Kazutoshi Hirohashi, Yokohama, JP;
Victor Company of Japan, Ltd., Yokohama, JP;
Abstract
In a quarternary differential PSK demodulator, a QPSK input signal is applied to first and second synchronous detectors to which carriers with a 90-degree phase difference therebetween are respectively applied from a voltage-controlled oscillator. A first double-balanced phase detector multiplies the outputs from the synchronous detectors. A second phase detector squares the output of the second synchronous detector. A third double-balanced phase detector provides multiplication of the outputs of the first and second double-balanced phase detectors to generate an output having four times the frequency of the outputs of the synchronous detectors to cancel the information carried by the input PSK signal. A loop filter converts the output of the third phase detector to a DC phase control signal to be applied to the voltage-controlled oscillator.