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:
Feb. 16, 1993
Filed:
Jan. 31, 1992
Andrew G Stove, Reigate, GB;
U.S. Philips Corporation, New York, NY (US);
Abstract
The frequency-versus-time characteristic of the output signal of a swept-frequency radar is linearized by determining departures from linearity of the phase-versus-time characteristic of the beat signal obtained between an actual return from a selected radar target and a sample of the current radar output signal, and applying oppositely-directed corrections to the frequency-versus-time characteristic. The relevant beat signal is selected from the output signal of a mixer (8) by performing special analysis in a Fast Fourier Transform (FFT) calculating circuit (15) and then performing an inverse FFT on a windowed portion of the FFT obtained. A second or higher-order polynomial is then fitted to the phase-versus-time characteristic of the selected beat signal after it has been expressed as time versus phase, and correction terms are derived from the coefficients of this polynomial. The radar output signal is generated by a voltage-controlled oscillator (1) controlled by a control voltage generator (7). The generator comprises a voltage source (27) and a cascade combination of integrators (18,19,20) outputs of which are connected to a voltage summing circuit (13) via respective multipliers (32,33,34,35). The correction terms are applied as multiplication factors to the higher-order multipliers (33,34,35).
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