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:
Apr. 22, 1986
Filed:
Mar. 21, 1983
Kabushiki Kaisha Koden Seisakusho, Tokyo, JP;
Abstract
A variable-narrow-band rejection filter is inserted in a reception signal path for rejecting a jamming wave. Signals at input and output terminals of the narrow-band rejection filter are picked up by a pair of first and second bandpass filters each having a center frequency that can be passed thereby which is equal to a rejection frequency of the narrow-band rejection filter. A phase difference between outputs from the bandpass filter is detected by a phase comparator, and the detected signal is supplied through a switch to a hold circuit in which the supplied signal is held. The rejection frequency of the narrow-band rejection filter is adjusted into conformity with the jamming wave frequency by an output from the hold circuit. The levels of the output signals from the first and second bandpass filters are detected respectively by a pair of first and second level detectors, and the detected outputs are compared by a comparator. The foregoing switch is kept off as long as the level of the signal at the input terminal of the narrow-band rejection filter is smaller than the level of the signal at the output terminal thereof.