| 摘要 |
PURPOSE:To detect the input signal level of front end of superregenerative system, by detecting the frequency shift in quenching frequency of the quenching oscillating circuit, in the superregenerative receiver. CONSTITUTION:The reception input received at the antenna is amplified at the buffer amplifier 2a of superregenerative system front end, and it is mixed with the quenching output voltage, it is converted into a low-frequency output with the low pass filter 2c. After it is amplified at the next low-frequency amplifier, the alarm device is driven via the rectifying, wave shaping and identifying circuits. The output of the quenching oscillation circuit 2b is fed to the band pass filters 121-12n having the frequency characteristics of f1<f2<...<fn and the frequency shift detecting means consisting of the signal level discriminating output 3. Since the frequency shift of the quenching output is proportional to the level of the electromagnetic wave signal, an output is generated only to the filter 121 when the electromagnetic wave signal level is e1, and an output is generated at the discriminating output D1, allowing to measure the signal level. |
