| 摘要 |
<p>PURPOSE:To eliminate amplitude distortion without losing a narrow band characteristic by applying SSB modulation by a voice signal, giving the carrier to the result so as to form a transmission signal, receiving the signal at the reception side and using an amplitude limiter so as to attain frequency detection while making the amplitude constant. CONSTITUTION:A voice 1 is inputted, an output of a local oscillator 2 is used and an SSB modulator 3 generates a lower side band SSB modulation wave. An output of the local oscillator 2 is added to an output of the SSB modulator 3 by an adder circuit 4, after the result is converted into a radio frequency by an up-converter 5, the result is amplified by a transmitter 6 and irradiated from a transmission antenna 7. The signal is received by a reception antenna 9 in a reception section 17, converted into an intermediate frequency band by a converter 10, amplified by an intermediate frequency amplifier 11 to boost the level to a level required for reception processing. The output is led to a limiter 12 to eliminate the amplitude distortion caused on a propagation path, the result is detected by a frequency detector 13 to obtain a voice frequency signal. The output of the frequency detector 13 is equalized by an equalizer 14 having a characteristic of -6dB/oct and amplified by a voice band amplifier 15.</p> |
