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:
Jun. 07, 1988
Filed:
Mar. 20, 1987
Fujitsu Limited, Kawasaki, JP;
Abstract
A call meter signal receiver is provided for a subscriber's private metering system operated by a call meter signal sent from a central office. The receiver is operable both by common mode and normal mode signals. The receiver is small sized and can be installed in a central office trunk of private branch exchanger equipment. The call meter signal receiver is composed of a frequency tuned receiver including two buffer circuits, the first one for receiving the common mode and the second one for receiving the normal mode signal. The first buffer circuit is connected to the input side of a hybrid circuit of the COT, and has a high impedance, while the second buffer circuit, for receiving the normal mode signal, is connected to one of the output terminals of the hybrid circuit, and has a high impedance for voice signals. The outputs of these buffer circuits are fed to the frequency tuned receiver composed of a phase locked loop, of which frequency is tuned to 50 Hz, 12 kHz or 16 kHz by switching an externally attached circuit composed of a capacitor and resistors.