| 摘要 |
In a remote alarm installation an alarm signal emitter device and a local selector switch are associated with local telephone junction points which are connected via respective telephone lines to a control room. The selector switch normally connects the local telephone junction point to its telephone line. When an alarm signal emitter device generates an alarm signal, this controls the selector switch in such a way that it connects, instead of the local telephone junction point, the output from the alarm signal emitter device to the telephone line so that the alarm signal is transmitted into the control room. Each alarm signal indicates the kind and place of the alarm and the information is reproduced in the control room. Each alarm signal emitter device contains a number of alarm signal emitters. All of the alarm signals are transmitted in the form of a combination of different frequencies from a generator, the frequency combinations being different from one another. |
