| Satellite Laser Ranging(SLR), which appeared in the mid 1960's, is one of the high precise space techniques. After almost forty years' development, the single-shot ranging accuracy has reached sub-centimeter level and it has been applied in many scientific fields. In recent years, high repetition-rate SLR is developing fast. The high repetition-rate SLR system is small and light with high reliability, which is advanced in SLR. The laser used in the system has low power, so it won't damage the components of the laser-generator and the laser system. Shanghai Astronomical Observatory is preparing to research this domain. Event timer, as one of the key parts to realize the high repetition-rate SLR, solves the problem of low repetition rate in the principle. The event timer has been researched for many years abroad, but the related research about SLR in our country is rare. So to develop the event timer with our own intellectual property is an urgent and essential work to keep pace with the trend of the international SLR technology.In the paper, a solution of a circuit system, which uses interpolation principle to enhance the precision of performing the measurement of event time, is proposed. The operation principle and the main function modules of the event timer sample are detailed analyzed. A high precision Time to Digital Converter (TDC), which raises the precision of the interpolation, is introduced. Moreover, using VHDL to program the FPGA which performs most digital function of the system, makes the circuit low-cost, more flexible and easier to be upgraded.At the end of the paper, the experiment data proves that the sample circuit can perform event time recording correctly and achieve 1.6×10<sup>10S precision, which fulfills the anticipated goals. |
