System for transmitting emergency calls from persons requiring a

Details System for transmitting emergency calls from persons requiring a System for transmitting emergency calls from persons requiring a

1982-09-13

1984-08-21

Pellinen, A. D.

179 2A, H04M 1104

Patent

active

044671423

ABSTRACT:
A system for transmitting an emergency call from a person requiring assistance. The system includes an emergency calling device coupled via a telephone exchange system to an emergency call receiving center having an operator. The calling device automatically dials a predetermined emergency telephone number upon actuation of a sensor by the person requiring assistance for placing a call to the emergency center. A first data device is provided for transmitting predetermined emergency data by frequency keying in the voice band to the emergency center. An intercommunication set in the calling device establishes a voice connection between the person requiring assistance and the emergency center operator. The intercommunication set is switchable between states of voice transmission and voice reception. A first control unit in the calling device is responsive to a first operating mode control signal for switching in the first data device and switching out the intercommunication set, and is responsive to a second operating mode control signal for switching in the intercommunication set and switching out the first data device. In the emergency center a control unit controls the transmission of a control tone to the calling device. The control tone constitutes the first operating mode control signal and the lack of the control tone constituting the second operating mode control signal. A second data device in the emergency center selectively transmits voice direction control signals by frequency keying in the voice band for controlling the state of the intercommunication set in the calling device.

REFERENCES:
patent: 3213200 (1965-10-01), Vogelman
patent: 3906491 (1975-09-01), Gosswiller et al.
patent: 4009342 (1977-02-01), Fahrenschon et al.
patent: 4064368 (1977-12-01), Dibner
patent: 4338493 (1982-07-01), Stenhuis et al.
patent: 4392125 (1983-07-01), Iwata
"Hutte IV B Fernmeldetechnick"[Communication Art], 28th Edition, Berlin and Munich, 1962, p. 730.

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