| 摘要 |
PURPOSE:To execute exactly the indication of an electric field intensity, irrespective of a modulation degree of a receiving radio wave by supplying an output signal of a difference between the detected output of a peak detecting circuit and the detected output of an audio detecting circuit, to a field intensity measuring instrument. CONSTITUTION:An output signal (v) of an intermediate frequency circuit 5 is supplied to a peak detecting circuit 6 and an audio detecting circuit 7. The detecting circuit 7 is constituted of a detecting diode D1 and a time constant circuit consisting of a resistance R1 and a capacitor C1, and an audio detecting wave vaf appearing in a point A is obtained by an expression I . To each base of transistors Q3, Q4 of the detecting circuit 6, an AC portion of the output signal (v) is supplied, therefore, Q3 and Q4 are operated to an on-state alternately, and in accordance with its current quantity, a current idet flowing through a transistor Q5 is controlled. idet is obtained by an expression II. A corrector current iQ7 of the transistor Q5 corresponds to a detecting output vaf supplied through a variable resistor VR1, therefore, by setting so as to attain iQ7=C.Vaf, and b=C. a, the detecting current having no relation to a modulation degree is supplied to a field intensity measuring instrument 11.
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