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:
Jan. 21, 1986
Filed:
Jul. 08, 1983
Bernard L Lewis, Fort Washington, MD (US);
Frank F Kretschmer, Jr, Laurel, MD (US);
The United States of America as represented by the Secretary of the Navy, Washington, DC (US);
Abstract
A digital pulse expander-compressor for generating polyphase coded pulses which are highly doppler tolerant and have autocorrelation functions which are identical under frequency sweep reversal. The expander-compressor comprises an input expansion circuit for generating N replicas of a pulse to be expanded, a matched filter FFT with phase weights disposed in each input thereto, and phase inverters disposed in every other output therefrom, and a time dispersion circuit for appropriately adding the pulses from the FFT output to yield an expanded or compressed pulse. The phase weights to be inserted at the inputs to the FFT are determined by the equation .phi..sub.n =.+-..pi.(n-1/2).sup.2 /.rho. for a PP-3 code or .phi..sub.n =.+-.[.pi.(n-1/2).sup.2 /.rho.-.pi.(n-1/2)] for a PP-4 code, where .rho. is the pulse compression ratio and n varies from 1, 2, 3 . . . .rho..