In an elevator system floors each include: a hall registration device that places a plurality of car calls for moving a car to destination floors different from one another; and a display device that displays the car that has been assigned the plurality of car calls. A first module receives and transmits the display data to at least one intermediate module, which passes the display data along the series in a first direction. The differential amplifier circuit includes a differential pair of coupled transistor circuits including a leading transistor circuit and a lagging transistor circuit. The digital image synthesizer circuit is arranged to process the phase sample data to form a false target signal, which is input to a signal transmitter system arranged to transmit the synthesized false target signal so that it can be received by a radar system. a microprocessor or a chip-card processor performing information encryption in an apparatus may reveal the security sensitive information. Key information is stored in, and the logical tree is supported by, a directory service.