3866206 is referenced by 13 patents and cites 3 patents.

A remote electrical signalling system in which emergency call stations are manually operable to communicate with a home station, and a confirmation signal is automatically transmitted back from the home station when a call signal has been properly received. The call stations each include an electromechanical generator to power both a emergency signal transmitter section and a confirmation signal receiver section. Switch means are provided to direct a limited duration generator output first to the transmitter section and then to the receiver section. Power is recycled back to re-energize the transmitter section if a confirmation signal is not received within a pre-determined period of time.At the home station emergency calls are received and the call station identified. A blocking circuit prevents the recording of an identifying digit or the transmission of a confirmation signal unless the previous digits of the call station identification have been recorded.

Emergency signalling system having manually operated generator
Application Number
Publication Number
Application Date
July 17, 1973
Publication Date
February 11, 1975
Rane Subhash R
Labib Ahmed H
DeGiorgio John A
Solid State Technology
H04b 01/04
G08B 25/01
View Original Source