Position determination system and building protection arrangement involve operative method

The position determination system and building protection arrangement involve an appropriate operative method. A configuration involves a portable device (10) and fixed stations (12) located in rooms of a building of which individual walls (14) of a passage (16) and rooms (18) are involved. The fixed stations are wireless access points and the portable device is a portable computer, such as a personal digital assistant with a wireless receiver and preferably a transmitter. The portable device receives signals from the fixed stations. The portable device measures the strength of the signals received from each fixed station. The received signal strengths are a function of the distance between the portable device and the different fixed stations. Based on the measured signal strengths the position of the portable device is determined. However, the received signal strengths are dependent upon several factors, such as the sensitivity of the receiver, whereby a position determination cannot be entirely reliable for a number of reasons. Nevertheless, it appears that the effect of such factors can be eliminated by the use of the measured received signal strengths from several stations.