Installation for data transmission with correction of phase error

A system for transmitting phase modulated at a comprising:

• an inquiry unit in the form of an emitter-receiver and
• a transponder arranged as a receiver-emitter such that a transmission of data takes place in at least one direction between said inquiry unit and said transponder, said transponder including a phase modulated emitter controlled by initial data, said phase modulated emitter acting on a signal derived from a carrier emitter by said inquiry unit,
• and a phase demodulator wherein said phase demodulator comprises inputs for receiving a phase modulated signal transmitted by said transponder to said emitter-receiver and for receiving an unmodulated reference signal derived from said carrier and processor means for recovering a sequence of said initial data from said phase modulated signal and from said unmodulated reference signal independently of a carrier phase shift .mu. between said reference signal and the carrier component of said phase modulated signal, wherein,
• said phase demodulator comprises a first stage yielding the raw real and imaginary components of the phase modulation of said phase modulated signal and means for the correction of said carrier phase shift .mu. of said phase modulation, and
• said processor means recovers said data by determining axis rotation according to the equations:
• X=xcos .mu.+ysin .mu., or
• Y=ycos .mu.-xsin .mu.,
• wherein x is the raw real component, y is the raw imaginary component, Y is the imaginary component, and X is the real component of said phase modulation.