| 摘要 |
Phase discriminator in a receiver of a system for data transmission by means of phase modulation of a carrier. The phase discriminator comprises a calculating unit arranged for receiving digital signals, whose associated signal samples occur at a rate equal to the data modulation rate, the digital signals being representative of the inphase and quadrature components of the received passband signals at each sampling instant and of the inphase and quadrature components of a reference carrier at a preceding sampling instant. This calculating unit calculates the signal samples of digital signals which are representative of the in-phase and quadrature components of a signal which is derived from the received passband signal by a phase shift over an angle which is equal and opposite to the phase of the reference carrier at the preceding sampling instant. The digital signals supplied by the calculating unit are applied to a decision circuit which at each sampling instant determines the phase variation of the transmitted carrier during one sampling period and reproduces the corresponding phase jump. In case the reference carrier is locally generated, the decision circuit also supplies an error signal for locking the phase of the local reference carrier on the received carrier. |
