RADIO WAVE INTERFERENCE DETECTION SYSTEM

摘要

PURPOSE:To detect the quantity of radio wave interference with high accuracy by obtaining the error of FM-AM conversion generated in an FM radio equipment from the 1st radio wave interference power ratio obtained from the amplitude component as a power interference error power ratio from the FM demodulated wave and subtracting the error. CONSTITUTION:An output from an FM antenna 10 is converted into an IF signal by the frequency conversion circuit 14 of an FM receiver 12 and its signal is fed to a limiter amplifier 18 and a logarithmic detector 20 via an IF filter 16. Further, an output subjected to amplitude limit by the amplifier 18 is demodulated by an FM demodulator 22 and outputted and fed to an FM-AM converter equivalent circuit 24. The output of the circuit 24 is fed to a power detection circuit 28 via an HPF 26, square detection is applied according to the characteristic of the circuit 24 and the result is fed to a subtraction circuit 30. Further, the output detected by the detector 20 is processed by an HPF 32 and a power detection circuit 34, and the logarithmic detection output is subjected to square detection and the result is fed to the circuit 30. Then the error by the FM-AM conversion is obtained from the demodulated wave as a power interference error power ratio and the radio wave interference quantity is detected with high accuracy.