| 摘要 |
<p>PURPOSE:To improve the transmission spurious characteristic, to simplify the modulation circuit and to make the selectivity of an intermediate frequency free by using a sound band frequency so as to modulate respectively a crystal oscillator and a voltage controlled oscillator. CONSTITUTION:The voltage controlled oscillator 1 and the crystal oscillator 11 are modulated by a frequency of sound band, the result is fed to a mixer 8 generating the 1st local oscillation source of the reception stage, the modulation is released and the 1st mixer 7 of the reception stage is subject to offset via a band pass filter 9. Thus, the transmission output frequency propagated through an antenna from the transmission stage keeps the difference between the input frequency being an incoming radio wave acquired by the antenna and the 1st intermediate frequency of the reception stage, that is, keeps a deviation and simultaneous communication is attained in any channel.</p> |
