| 摘要 |
PURPOSE:To enable desired frequency change, by selecting the intermediate frequency for transmission system to a frequency higher by a fraction of transmission frequency, and changing the frequency of local oscillation output signal only. CONSTITUTION:In a transmission system, the frequency f(IFt) of the intermediate frequency signal of transmission system IFt modulated with the base band signal Bin to be transmitted is made about to a fraction of the transmission frequency, allowing to reject unnecessary waves with a filter 13, even if the local oscillation output signal mut is changed in the range of about several 100MHz. Thus, the intermediate frequency of transmission system f(IFt) is kept constant to change the frequency f(mut) of the local oscillation output signal mut, allowing to change desired frequency. In the reception system, since the frequency f(IFr) of the intermediate frequency signal IFr of the 1st reception system is a high frequency, unnecessary waves can be rejected at a filter 36. Thus, the transmission/reception frequency in specified frequency band can arbitrarily be changed. |
