| 摘要 |
PURPOSE:To improve the quality of a microwave radio communication circuit which transmits a pilot signal, by detecting a noise level accurately by controlling the detection sensitivity of a detector by using the DC voltage of LPF through the noise detecting circuit of the communication circuit. CONSTITUTION:A prescribed pilot signal transmitted via the communication circuit is extracted through BPF1 and detected by detector 2. Its detection output is extracted through LPF3 as a pilot signal level. On the other hand, the AC component of this detection output is extracted through HPF4 and detected by detector 5, and the DC component of its detection output is extracted through LPF6. For this purpose, detector 7 is provided which uses the DC voltage of LPF3 as a control voltage and varies the detection sensitivity with the control voltage. Thus, the noise level can accurately be detected and the reliability and quality of the communication circuit can be improved. |
