PLL automatic presetting system and initializers

The present invention discloses a PLL automatic presetting system and initializers. PLL automatic presetting system is composed of a voltage controlled oscillator, a frequency doubler, a directional coupler, a mixer, a sampler, a phase detector, an integrator, three frequency divider, a voltage comparator and programmable chips the closed-loop control system. Pre-locked loop method based on the automatic presetting system can automatically achieve rapid and accurate pre-locked loop, saving time and effort, greatly improving the efficiency of mass production. More important point is that when large changes in ambient temperature occurs, the software detected after the preset value larger deviation, can quickly and automatically recalibrate the preset value, so as to ensure the instrument to work properly.