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:
Jul. 16, 1985
Filed:
Jul. 14, 1982
Applicant:
Inventors:
Takeo Kusama, Chigasaki, JP;
Hisasi Kiyonaga, Hadano, JP;
Assignee:
Hitachi, Ltd., Tokyo, JP;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
H04M / ; H04Q / ;
U.S. Cl.
CPC ...
34082505 ; 370 15 ; 1791 / ; 375 10 ;
Abstract
In a return loop control system in a data transmission system having data transmission units such as modems connected at opposite ends of a transmission line, a return loop being formed at one of the data transmission units by a command signal from the other data transmission unit when the transmission line, modulator, demodulator, etc. are to be tested. Where a data to be transmitted is sent out a predetermined time period later than the send-out of a signal for establishing a communication status to the transmission line, a command signal for forming a return loop is sent out within the predetermined time period.