  In this work, we have built an experimental setup to simulate the clock noise
transmission with two spacecrafts and two optical links, and further
demonstrated the extraction of picometer level signal drowned by the large
laser frequency noise and clock noise with the data post-processing method.
Laser frequency noise is almost eliminated by using the idea of time-delay
interferometry (TDI) to construct an equal arm interferometer. Clock
asynchronism and clock jitter noise are significantly suppressed by laser
sideband transmitting the clock noise using an electro-optic modulator (EOM).
Experimental results show a reduction in laser frequency noise by approximately
10^5 and clock noise by 10^2, recovering a weak displacement signal with an
average amplitude about 60 picometer and period 1 second. This work has
achieved the principle verification of the noise reduction function of TDI
technique to some extent, serving the data processing research of space-borne
gravitational wave detection.
