在不同频率标称值信号间的相位差变化具有群连续特性的情况下,提出了不同频率标称值信号间进行直接数字化锁相的方法.该方法利用模数转换器提取被控频率的数字电压值,此电压值反映了被控频率的相位信息,提取出过零点的电压值形成闸门的开关点,求得被控频率的小频偏值,以此输出控制电压信号,进而控制高稳压控振荡器,将被控频率锁定.实验结果表明,由于省去了大量频率变换线路,降低了复杂电路所引起的噪声影响,实现了高精度锁定,被控频率短期稳定度可达到10-12/s的量级,并且具有良好的相噪指标.
Based on thecontinuous character of the phase difference group between frequency signals of different nominal values, a method for direct digital phase lock between the different nominal value signals is proposed. The A/D converter is utilized to extract digital voltage value of the controlled frequency signal, whichreflects the phaseinformation. The switch point of the gate is generated by extracting the zero-crossing digital voltage value, then the frequency offset is obtained, on the basis of which the control voltage is obtained to control VCOCXO, and the frequency is locked. The'experiment shows that the noise brought by the common complex circuit is reduced because of the simplified frequency transformation circuits, so that high precise locking is realized. The short term stability can reach the 10-12/s order of magnitude, and the phase noise index is good.