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:
May. 11, 1976
Filed:
Oct. 21, 1974
Thomas E Clark, San Mateo, CA (US);
Robert J Tracey, San Mateo, CA (US);
Ronald J Violet, Belmont, CA (US);
GTE Automatic Electric Laboratories Incorporated, Northlake, IL (US);
Abstract
A digital phase detector which periodically detects the phase angle .theta..sub.k of a carrier signal in which data are encoded as discrete phase changes. A coherent or differential phase-modulated carrier signal is split into its in-phase and quadrature phase components R.sub.o Sin.theta.(t) and R.sub.o Cos.theta. (t). Each signal component is sampled at a predetermined modulation interval and converted into a digital word having the form R.sub.o Cos.theta..sub.k and R.sub.o Sin.theta..sub.k. In one configuration, the two signal components are applied to a digital divider network which forms the quotient .PSI. of the two digital words such that .vertline..PSI..vertline..ltoreq. 1. The quotient .PSI.is applied to a data look-up ROM, programmed for Tan.sup.-.sup.1 operation, which forms a digital reference phase angle .PHI.limited to an angle .ltoreq. 45.degree. is corrected by selection logic to form the desired phase angle .theta..sub.k. Once .theta..sub.k is known for each modulation interval, the encoded data may be readily extracted, since .theta..sub.k is proportional to the encoded data.