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:
Jul. 04, 1978
Filed:
Feb. 22, 1977
David Paul Casasent, Pittsburgh, PA (US);
The United States of America as represented by the Secretary of the Navy, Washington, DC (US);
Abstract
A method and apparatus for determining the value of a Doppler frequency shift component .DELTA.f present in a signal f .+-. .DELTA.f employing a correlation process which utilizes the Mellin transform and is scale invariant. The location of the correlation peak in the reference coordinate system used provides a measure of the magnitude of .DELTA.f. The sequence of steps involved in the correlation process when optical apparatus is used include forming a transmittance pattern of the signal f .+-. .DELTA.f, which has a horizontal scale that is the natural log of the time scale of the original signal, forming a similarly scaled transmittance pattern of the reference signal, f, and utilizing the first patttern in the input plane of a frequency plane correlator that has a holographic matched spatial filter that is produced from the second pattern and contains a term corresponding to the conjugate of the Mellin transform of the reference signal in its frequency plane.