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. 20, 1976
Filed:
Apr. 27, 1973
Hitachi, Ltd., , JA;
Abstract
A multi-frequency signal receiving circuit comprising a check circuit for discriminating the existence of a predetermined number of signal frequencies constituting a signal to produce an output, a timing circuit for delaying the output of the check circuit, a rectifying circuit for receiving the signal to detect the received signal energy and produce an output, a timing circuit for delaying the output of the rectifying circuit, an AND gate circuit for receiving the outputs of the two timing circuits to produce an output, and control means for controlling the transmission of the signal to the output circuit of the receiving circuit in accordance with the output of the AND gate circuit, whereby the normal operation of the receiving circuit can be ensured even when the signal frequencies arrive with a large arriving time difference and the operation start time is quickened.