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. 02, 2002
Filed:
Jan. 22, 2001
Herbert Kleiber, Ludwigsburg, DE;
Airsys Navigation System GmbH, Stuttgart, DE;
Abstract
A method for monitoring a localizer course facility in an instrument landing system, including modulating a course signal at a first signal frequency and at a second signal frequency, and transmitting the modulated course and clearance signals. The method also includes detecting by sensors the modulated course and clearance signals, demodulating the modulated course and clearance signals, monitoring variables obtained from the demodulated course and clearance signals to ensure that the variables are within limit values, and subjecting the demodulated course and clearance signals to Fourier transformation. Also included is determining a first phase difference for a first modulation frequency between the course and clearance signals detected by the sensors and a second phase difference for a second modulation frequency in the course and clearance signals, betweem the course and clearance signals detected by the sensors. Further, the phase differences which have been determined for the first and second modulation frequencies are compared with the limit values provided for each of these differences and a warning signal is produced if the limit values are infringed.