Importance

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Abstract

In a receiver comprising a demodulator for demodulating a received signal into a demodulated signal, a carrier phase synchronizing circuit comprises a phase rotating circuit for phase rotating the demodulated signal into a phase-rotated signal in response to a phase rotation control signal, a first carrier phase extracting circuit for extracting a first carrier phase error estimation signal from the phase-rotated signal, a second carrier phase extracting circuit for extracting a second carrier phase error estimation signal from the phase-rotated signal, a comparator for comparing a second carrier phase estimated error value indicated by the second carrier phase error estimation signal with a threshold value to produce a comparison result signal, a selector for selecting one of the first and the second carrier phase error estimation signals as a selected carrier phase error estimation signal in response to the comparison result signal, and a low-pass filter for filtering the selected carrier phase error estimation signal to produce the phase rotation control signal. The low-pass filter may have a controllable passband controlled by a bandwidth control circuit which responds to the comparison result signal. The carrier phase synchronizing circuit may further comprise an equalizer for equalizing the demodulated signal before supply to the phase rotating circuit in response to an equalization control circuit which responds to the comparison result signal.

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