An improved phase locking method with real-time phase feedback assisted by pilot-tone

There are different kinds of noise in the process of space gravitational wave detection, among which ADC sampling jitter noise is a non-negligible noise source. This paper presents an improved method to reduce the ADC sampling jitter noise. The phase compensation assisted by pilot-tone is coupled into the phase locking system of the input beat signal, differing from the traditional method with post-processing. Moreover, the transient frequency of the input beat signal is introduced for real-time phase compensation instead of setting a static frequency, which may fluctuate in the range of $6 \mathrm{MHz}-$ 24 MHz due to the Doppler shift caused by the relative motion of spacecrafts. The simulation results show that compared with the traditional method, the output signal of the proposed method can effectively improve the phase correction ability of input beat signal and achieve a better phase locking effect. In the frequency domain, the ground noise is reduced by about 10 dB. The phase compensation capability in the time domain is improved by about 0.08 rad.