JPS641353A - Demodulator circuit - Google Patents

Abstract

PURPOSE: To make sudden clock phase control such as kickoff, by controlling the phase of a reference carrier by using at least the relation between the changing quantity of a reference clock phase and frequency of the reference carrier.

CONSTITUTION: A phase shifting quantity is controlled in such ways that a sample 1 uses an AD converter, a carrier reproducing circuit 3 is provided with a frequency register 31 and phase register 32, and a clock reproducing circuit 2 is provided with an original oscillating clock 22 and phase shifting circuit 21. A clock phase fluctuation detector 4 detects the fluctuating quantity Δof a clock phase and an arithmetic circuit 5 inputs the content (f) of the register 31 and the fluctuating quantity Δ and calculates the product a×f×Δ of the content (f), fluctuating quantity (Δ), and a previously given constant (a). The (a) is a quantity corresponding to the reciprocal number of a nominal sampling rate. The phase register 32 can add a number from the outside of a carrier reproducing section and adds a number to the product a×f×Δ. Therefore, when a clock phase is suddenly controlled, the carrier phase can be controlled so that no disturbance is produced in the carrier reproducing system independently of the operation of the carrier reproducing system.

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