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Individual
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Individual
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Priority to FR964612DpriorityCriticalpatent/FR964612A/fr
Application filed by IndividualfiledCriticalIndividual
Priority to GB963148Aprioritypatent/GB647852A/en
Priority to CH269678Dprioritypatent/CH269678A/fr
Publication of GB647852ApublicationCriticalpatent/GB647852A/en
H04M11/00—Telephonic communication systems specially adapted for combination with other electrical systems
H04M11/04—Telephonic communication systems specially adapted for combination with other electrical systems with alarm systems, e.g. fire, police or burglar alarm systems
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Engineering & Computer Science
(AREA)
Signal Processing
(AREA)
Fire Alarms
(AREA)
GB963148A1948-04-061948-04-06Fire alarm signal systems
ExpiredGB647852A
(en)
Improvements in or relating to apparatus adapted to provide an indication or effect a control, in dependence upon a frequency difference between two electrical oscillatio ns