| 摘要 |
PURPOSE:To simplify the constitution of a detector by limiting a subject to be detected only to the signal that is modulated by a binary digital signal among the frequency modulated waves in order to attain the use of an amplitude control circuit at a base band and to omit a multiplier circuit. CONSTITUTION:A binary digital signal is supplied to an input terminal 11, and the output of a local oscillator 30 which oscillates a frequency equal approximately to the center frequency of said digital signal is branched into two parts. One of two branched outputs is supplied to a mixer 22 and frequency converted into a base band. While the other output is shifted by 90 deg. through a phase shifter 35 to obtain a signal. This signal is supplied to a mixer 21 and frequency converted into a base band. Then only a desired signal is extracted out of said signals through LPF41 and 42, and binary coded signals Q and I are outputted from binary coding circuits 51 and 52. These signals Q and I are supplied to an exclusive OR circuit 60 and a reference signal generating circuit 70. A reference signal Z of the circuit 70 is supplied to an exclusive OR circuit 65 and a pulse generating circuit 75. The subject to be detected is limited only to a signal that is modulated by the binary digital signal. Thus the constitution of a detector is simplified. |
