Laser back scatter: Limitation to higher repetition rate [kHz] Satellite Laser Ranging system

Abstract

Satellite laser ranging (SLR) with higher repetition rate is the recent trend for its various advantages. Laser backscatter (coincidence between recently transmitted pulses and received pulses near the detector) is found to be a constraint for the repetition rates higher than 20 kHz, due to, overlapping with photons returning from a satellite with the present constellation of most of the SLR systems. Such an overlap occurs at every 75 km satellite distance change at 2 kHz repetition rate, and remains for about 7.5 km; for a 20 kHz system however, it will occur after every 7.5 km and remains for 7.5 km, resulting in constant backscatter overlap – leaving no chance to avoid it. The resulting noise is 5 times more than before causing a serious problem in detection and lowers the signal to noise ratio of the overall SLR system. However, decreasing energy per shot at higher repetition rates – assuming a constant power laser – the resulting backscatter may decrease fractionally.

Keywords

• Satellite laser ranging
• Higher repetition rate
• Noise
• Retro reflectors