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:
Oct. 22, 1991
Filed:
Apr. 18, 1990
Eckhard Meissner, Munich, DE;
Franz Auracher, Baierbrunn, DE;
Siemens Aktiengesellschaft, Munich, DE;
Abstract
Method and apparatus for obtaining phase and/or polarization-insensitive optical heterodyne receiving for DPSK or ASK-modulated transmission signal wherein an intermediate frequency which is very low as compared to the data rate of the signals is utilized and at every clock of the transmission signal the phase of the signal is shift keyed between 0.degree. and 90.degree. at the start A1 and in the middle M of the clock time T and the polarization of the signal is shift keyed at least at the start A2 of the second and at the start A4 of the fourth quarter of the clock time T. The transmission signal which is shift keyed in this manner is received by a simple optical heterodyne receiver which has the special characteristics that an intermediate frequency filter ZFF is an integrator which integrates over a respectively one-quarter of the clock time T.