Abstract: A receiver designed to pick up an electromagnetic signal, comprises: a passive receiving antenna; a resonant circuit connected to the antenna, formed of passive components and replying, by transmitting an electric signal, to the electromagnetic signal picked up, and an electric signal processing circuit. This receiver also comprises a threshold comparator circuit defining a reference threshold and connected directly to the terminals of the resonant circuit to compare the electric signal, not amplified, with the reference threshold and to activate said processing circuit only when the amplitude of the electric signal exceeds the threshold. An object tracking system making use of the receiver described above is also disclosed.

Abstract: The invention concerns a device for the bidirectional displacement of an information support in which one drives alternatively the supplier spool for the rewinding or the receiver spool for the unwinding of the information support by means of mechanical driving means comprising only one motor and in which the inversion of the direction of displacement of the support is obtained through the reversal of the direction of rotation of the motor. The device comprises a frame provided with means intended to receive an information support and receiver and supplier spools; mechanical driving means comprising a motor as well as a member tilting between two positions, the one in which the supplier spool is driven in rotation and the other in which the receiver spool is driven in rotation and in which the inversion of the direction of rotation of the motor causes the movement of this tilting member from one of the said positions into the other.