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, 1981
Filed:
Dec. 26, 1978
Yoshiaki Kondo, Tokyo, JP;
Akira Okamoto, Tokyo, JP;
Ricoh Company, Ltd., Tokyo, JP;
Abstract
Data signals are transmitted from a transmission unit (12) through a hybrid coil (16) and transmission line (18) to a remote transceiver. Data signals of a different frequency are received from the remote transceiver through the transmission line (18) and hybrid coil (16) in a full duplex mode and passed to a reception unit (26). A ratio of the signal levels of the received data signals passed through the hybrid coil (16) in a desired manner to transmitted data signals which leak through the hybrid coil (16) in an undesired manner is sensed at a reception signal output of the hybrid coil (16). The resistance of a variable resistance pad (17) provided in the transmission line (18) is varied in accordance with the sensed ratio so as to adjust the ratio to a predetermined optimum value. The sensed ratio is a predetermined function of the impedance of the transmission line (18) as viewed from the hybrid coil (16). The amplification factors of transmission and reception amplifiers (14), (22) are also varied to compensate for variations in attenuation of the transmitted and received signals by the resistance pad (17).