Precise control of laser emission epoch in laser time transfer with high repetition rate

A satellite-ground laser time transfer (LTT) with high repetition rate will be carried out in the China’s space station. The onboard laser detector intends to adopt a fixed gated opening mode, which puts forward the control requirements of high repetition rate, high precision and high real time for laser emission epoch on the ground station. Based on the principle of range gate in satellite laser ranging (SLR), a precise control method of laser firing signal in satellite-ground LTT with high repetition rate was proposed, so that the uplink laser pulse could reach the detector within a short time after the onboard gate signal, which greatly reduced the background noise interference. This method could be implemented in a field programmable gate array (FPGA), which had the advantages of repetition rate greater than 10 kHz, control accuracy of 5 ns (200 MHz clock) and simple software interaction, etc. Combined its theoretical calculation accuracy and nanosecond jitter of the diode-pumped picosecond laser, the final realization accuracy of laser emission epoch was expected to be within 10 ns. It could meet control requirements of the laser emission epoch of the China’s space station LTT project and provide technical support for other LTT projects.