Granted Patent
Utility
US 4,876,489 · App. 07/290,875
Signal processing
Inventor:
Christopher Derrick Cawthorne
Patented Case
View Patent ↗
Granted: Oct 24, 1989
Filed: Dec 27, 1988
Inventor
Christopher Derrick Cawthorne
Assignee (at issue)
STC PLC
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.