| 摘要 |
PURPOSE:To detect a change point of a biphase PSK modulation signal by delaying an output signal of a mixer by a time in response to a period of phase shift quantity changeover so as to compare the polarity of an output signal of the mixer with the polarity of the delayed signal. CONSTITUTION:When a phase shift of a phase shifter is switched at a period taushorter than a period of a modulation signal phi(t), the polarity of an output signal A(t) of a mixer 3 is inverted for every increase in the phase shift by piin the case of figure (a), that is, for each lapse of a time 2tau. Moreover, the polarity of the output signal A(t) is inverted also at a changing point of the modulation signal phi(t). Thus, the polarity of an output signal B(t) of a polarity comparator 6 is positive over a time 2tau from a changing point of the modulation signal phi(t) and always negative in other cases. Then a state of an amplitude of the output signal A(t) of the mixer 3 being zero and a state of not being zero take place alternately for each increase in the phase shift by pi/2 in the case of figure (b). The polarity of the output signal A(t) of the mixer 3 is switched alternately to positive/negative when the amplitude is not zero. |
