Granted Patent
Utility
US 4,514,844 · App. 06/506,561
Duplex digital span transmission circuit arrangement
Inventor:
Thomas J. Perry
Patented Case
View Patent ↗
Granted: Apr 30, 1985
Filed: Jun 22, 1983
Inventor
Thomas J. Perry
Assignee (at issue)
GTE Automatic Electric Incorporated
This patent predates the USPTO's electronic file wrapper — prosecution documents from this era exist only in the Patent Office's paper records. A certified copy of the file history can be ordered from the USPTO's paper archives.