Granted Patent
Utility
US 4,571,711 · App. 06/457,264
Sonar apparatus
Inventor:
Victor J. Chadwick
Patented Case
View Patent ↗
Granted: Feb 18, 1986
Filed: Jan 11, 1983
Inventor
Victor J. Chadwick
Assignee (at issue)
Plessey Overseas Limited
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.