Patent ID: 8154393

Claim:
A warning system suitable for installation in a motorized road vehicle, the system comprising (1) an activity detector which, when it is placed in the vicinity of a mobile telephone which (i) when it is in a standby mode, generates RF signals of a first, transient, type, (ii) when it is being used in a communication mode, generates RF signals of a second, longer term, type, and (iii) does not generate any special RF signal for the purpose of activating a warning system, (a) automatically detects RF signals of the first or second type, (b) discriminates between RF signals of the first type and RF signals of the second type, (c) is activated when it detects RF signals of the second type, and (d) is not activated when it detects signals of the first type; and which, when it is in the vehicle, has a sensitivity such that it does not detect RF signals from mobile telephones outside the vehicle or, RF signals from transmitting stations transmitting to mobile telephones outside the vehicle; and (2) a display device which (i) is switched on by the activity detector while the activity detector is detecting RF signals of the second type, and is not switched on while the activity detector is detecting only RF signals of the first type, and (ii) when it is switched on, displays a visible warning signal.