Granted Patent
Utility
US 4,698,769 · App. 06/698,095
Supervisory audio tone detection in a radio channel
Inventors:
Ross McPherson, Kenneth Frank Smolik, David Thomson
Patented Case
View Patent ↗
Granted: Oct 6, 1987
Filed: Feb 4, 1985
Inventors
Ross McPherson
Kenneth Frank Smolik
David Thomson
Assignees (at issue)
American Telephone and Telegraph, Co.
Bell Telephone Laboratories, Inc.
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.