Research on precision measurement of phase difference between different frequency signals

Traditional phase comparison must be carried out between the two frequency sources with the same values. However, recent researches have found that phase comparison also can be implemented between frequency sources with different values and obtain higher resolution. The paper analyzes the phase difference regularity of arbitrary period signals' comparison. Discuss in detail that fine quantized phase step phenomenon and how the step value to reflect the higher resolution. When two signals with different frequencies are compared, their phase differences are in special order according to the frequency ratio, and, because of small frequency deviation existing, corresponding phase differences in every least common multiple period are different. As for the equivalent phase-discrimination frequency, ABf
_maxc
*, has very high resolution, under the condition of proper reference frequency, the technology in the paper can reach higher measuring resolution. As for the development of present base standard sources and the research on fine quantified phase step phenomenon between period signals, the signal comparison in RF band could reach ps resolution and even fs. Because the hardware used in detecting coincidence information will bring some trigger error and compared signals' own noise will bring some phase uncertainty, the software in connection with algorithm can be used in the technology. On account of instruments' own drift, pulse average method and pulse filling method can be used, and moreover, self-calibration. *: When the frequency values of compared signals are respectively f
₁
and f
₂
and their greatest common factor frequency is f
_maxc
, f
₁
= Af
_maxc
, f
₂
=Bf
_maxc
,.