| 摘要 |
<p>The invention relates to a demodulation apparatus for a signal modulated on two quadrature axes by the pi /4-QPSK modulation technique alternately employing two phase-shifted constellations, this apparatus comprising: - a voltage-controlled oscillator (28) providing a local signal having substantially the carrier frequency, - demodulation means which use the local signal and provide, after filtering (30, 31), the phase P and quadrature Q components of the demodulated received signal, - phase locking means (32) producing a control signal (39) intended for controlling the oscillator (28) and incorporating a phase estimator (33) producing a phase estimation signal E (35), utilised in controlling the oscillator (28), this phase estimation signal being obtained from the phase P and quadrature Q components of the demodulated received signal. The phase locking means comprise means (34) of alternate reversal of the polarity of the phase estimation signal E (35), in tempo with the alternating of the constellations, and providing the control signal (39) intended for controlling the oscillator (28) after filtering (29) in the loop. <IMAGE></p> |
