| 摘要 |
PURPOSE:To attain small size, light weight and low power consumption by providing a crystal oscillator outputting a frequency at equal intervals of an input signal a means obtaining a frequency difference in the order of a local oscillator at equal intervals of frequency difference, a phase comparator and a phase locked loop. CONSTITUTION:The crystal oscilltator 11 is a crystal oscillator highly stable in frequency at equal intervals to an input signal. Signals of inptted frequencies f1 fn are time division multiplex signals having the frequency difference of equal intervals in the order of frequencies. A signal having a frequency difference fL2 -fL1 of local oscillators 7-1, 7-2 is obtained by a frequency converter 8-1, a phase detector 9-1 detects a phase difference between a signal of the difference frequency an output signal of the crystal oscillator 11, this output is applied to a VCO7-2 via loop filter 10-1 and controlled so as to eliminate the said phase difference. Thus, the shift in common frequency of the local oscillator and the frequency difference between the oscillators are suppressed by the characteristic of the crystal oscillator 11 and the difference in the intermediate frequency is eliminated. Thus, the local oscillator is constituted of a microwae oscillator with small-sized and low power consumption, and one crystal oscillator is enough for the circuit. |
