| 摘要 |
<p>PURPOSE:To simplify the construction employing a VCO serving both for transmission and local reception of signals by making IF to be a diffrence in the frequency oscillated between the times for transmitting and receiving it. CONSTITUTION:Signals S1 and S2 having a fixed voltage difference V1 including sinewave and triangular wave are applied to sample hold circuits 2 and 3 from an oscillator 1 where a sample holding is made at a cycle T1 of a timing signal from a control circuit 5. The output signal of the circuits 2 and 3 is introduced to a change-over circuit 4 and fed to a VCO7 as a control signal with a switching to transmitting or receiving it. With such an arrangement, the difference in the frequency oscillated by the VCO between the times for transmitting and receiving it becomes a center frequency of IFA11. This allows the VCO to be used in common for a transmitting oscillator and a receiving local oscillator.</p> |
