Emergency communications system
US3939417A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 18, 1973 |
| Grant date | Feb 17, 1976 |
| Priority date | — |
| Expiry date | Dec 18, 1993 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04B1/56
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A control console including a transceiver, a plurality of terminal stations positioned at spaced apart locations remote from the console and each including a transceiver connected to the console by RF or a wire line, and a plurality of call boxes positioned at spaced apart locations adjacent to each terminal station and including a transceiver in communication with the terminal station. When the hand set of a call box is lifted from the cradle a tone is transmitted through the adjacent terminal station to the console which then keys on all terminal station transmitters to indicate a busy line at other call boxes and to provide a ringing signal at the call box being used. Subsequent to transmission of the tone, a signal indicative of the address of the box and the condition of predetermined portions of the box is automatically transmitted to the console. When the console operator answers, full duplex communication is provided between the call box and the console.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.