System for contactless information transfer with phase modulation.

摘要

The invention relates to a system for contactless information transfer. The information transfer from a reading device to an information carrier takes place by means of the phase shift keying (PSK) technique. According to the invention, the at least one coil of the information carriers is connected to a phase demodulator comprising a phase-locked loop including a voltage-controlled oscillator. The output signal of the voltage-controlled oscillator is applied to a phase device which forms from the output signal a predetermined number of phase reference signals having a different predetermined phase relative to the output signal. The predetermined phases correspond with the possible phase jumps in the signal applied to the phase demodulator. Selection means are provided which select one of the phase reference signals and apply same, via a circuit with a relatively large time constant, to the input of the voltage-controlled oscillator for forming a phase-stable reference signal for the demodulation of the phase-coded data signal coming from the at least one coil. <IMAGE>