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. 04, 1977
Filed:
May. 14, 1975
Yasuo Fukata, Mitaka, JA;
Ryoichi Hatsumi, Nagareyama, JA;
Abstract
A signal identification system, in which a signal of a specified frequency included in an analog signal indicated by an input pulse train converted from the analog signal is detected from the pulse train. The input pulse train is multiplied by two reference wave pulse trains having peak valves following the signal of the specified frequency but displaced by .pi./2 in phase from each other, respectively. The results of the multiplications are separately accumulated. The signal of the specified frequency is identified by utilizing a fact that the absolute value of at least one of the accumulated values exceeds a predetermined threshold value in the range of a permissible frequency deviation of the signal of the specified frequency and in the range of its permissible level fluctuation. The decision of the above fact may be performed when the accumulation is achieved at a certain number of times, which is predetermined in view of a permissible frequency deviation and a permissible level fluctuation of the signal of the specified frequency.