| 摘要 |
PURPOSE:To enable the detection of C/N at a high accuracy with a simple circuit by forming a circuit so as to extract only noise power from signals received in an area high in C/N. CONSTITUTION:Output of a receiving band pass filter 1 is provided to an AGC amplifier (or a voltage limiting amplifier) 11. The output thereof is supplied to one input end of a mixer circuit 12 while output of a local oscillator 13 for generating a frequency signal almost equal to the carrier to the other input end thereof. Then, output of the mixer 12 is supplied to a band pass filter 14. The formation of such a circuit enables the extraction of only noise power from signals received in an area high in the C/N. A detection voltage corresponding to the C/N can be obtained by supplying the output of the filter 14 to a detector 16 through an amplifier 15. Thus, C/N can be detected at a high accuracy with a simple circuit. |
