| 摘要 |
PROBLEM TO BE SOLVED: To improve the articulation of a CW signal tone by correcting a delay characteristic of a low frequency amplifier stage in the reception of an amateur radio communication equipment so as to apply waveform shaping in a time base direction. SOLUTION: A CW signal whose frequency is converted into an intermediate frequency is given to a band signal filter 1, in which an undesired signal component is eliminated and the result is demodulated and the demodulated signal is filtered by a band limit filter 3. Then a low frequency amplifier 6 amplifies the filtered signal based on a control signal from a control signal generator 8 at a prescribed gain to make rising of the signal steep, and the control signal generator 8 generates the control signal in response to the level detected by a level detector 7 so as to control the gain of the amplifier 6. In this case, the operation of the control signal generator 8 is delayed slightly from a rising point of an output signal with a prescribed time constant. Thus, the time till the output signal of the amplifier 6 reaches the maximum amplitude from the leading is reduced depending on the gain and the maximum amplitude is limited to picture value to emphasize the leading of the signal thereby correcting the waveform. |
