| 摘要 |
PCT No. PCT/SE79/00188 Sec. 371 Date May 15, 1980 Sec. 102(e) Date Apr. 18, 1980 PCT Filed Sep. 13, 1979 PCT Pub. No. WO80/00630 PCT Pub. Date Apr. 3, 1980.In an installation for transmitting alarms, preferably in connection with attacks on persons, and for locating the alarm sender, there is at least one portable alarm sender 2 sending an alarm to a central alarm receiver (3) by radio. The senders each contain a memory (24) for a code unique to their position in the installation. The code is automatically set by fixed transmitters (1) having a small range, which transmit it electromagnetically, especially inductively, to the sender (2), the code being unique to the location of a transmitter and stored in the sender memory. When fixed transmitters (1) are arranged so close together that their unique codes are difficult to separate in the sender (2), a dummy transmitter (56) is arranged to prevent alteration of a code already stored in the memory (24) of the alarm sender, as long as the sender (2) is close to the dummy transmitter (56). The sender (2) also transmit a second code stored in a second memory, unique to the individual alarm sender and thereby to the carrier of the alarm sender. |
