Granted Patent
Utility
US 4,306,228 · App. 06/110,116
Security alarm system monitoring difference between sound signal components in two frequency ranges
Inventor:
Gunther Meyer
Patented Case
View Patent ↗
Granted: Dec 15, 1981
Filed: Jan 7, 1980
Inventor
Gunther Meyer
Assignee (at issue)
Licentia Patent-Verwaltungs-GmbH
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.