| 摘要 |
PURPOSE:To improve the reliability of equipment by subtracting FM thermal noise from mixed noise between FM distortion noise and the FM thermal noise so as to detect only the FM distortion noise thereby grasping accurately the deteriorating state of an FM radio communication equipment. CONSTITUTION:An FM receiver 3 of the Fm radio equipment detects an FM radio signal, outputs a base band via a power amplifier 4. Further, an intermediate frequency signal detector 8 detects an intermediate frequency (IF) signal and extracts only the FM thermal noise converted from the signal level. Then a base band signal is eliminated by a base band out-band BPF5 from the output of the amplifier 4, the result is amplified by a power amplifier 6 and a detector 7 outputs the mixed noise level. The mixed noise from the detector 7 and the FM thermal noise from a detector 8 are fed to an operational amplifier 13 of a differetial amplifier 9. Then only the FM distortion noise is outputted from the mixed noise to grasp accurately the state of deterioration of the Fm radio equipment by the differentiation characteristic. |
