| 摘要 |
PURPOSE:To obtain a phase demodulating circuit strong against the variation of temperature or the like by applying local oscillation to reduce the frequency of a carrier and detecting the deviation from a set value to correct the deviation to zero. CONSTITUTION:A phase modulated signal and local oscillation OMEGA are mixed by a mixer 2, and the output of the mixer 2 is added to a phase signal 0(t) as it is and is allowed to pass a low pass filter 3 to take out only a signal having an angular frequency (omega-OMEGA). A delay signal R(t) is multiplied in a two multiplying circuit 9 by two and an original signal S(t) is multiplied in a two- multiplying circuit 10 by two, and phases are detected by a phase detecting circuit 11. A deviation is extracted from the output of the phase detecting circuit, and the control voltage of a voltage controlled oscillator 1 is changed in accordance with the deviation . By this feedback, the deviation is corrected to 0.
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