Design of a very high sensitivity acquisition system for a space GNSS receiver

Increasing the GNSS receiver sensitivity and robustness in very harsh environments has become a central topic for the GNSS community. This paper addresses the design of a very High Sensitivity (HS) acquisition scheme for weak GNSS signal detection down to 5/10 dB-Hz in the particular space environment of the Lunar Low Orbit. A theoretical analysis for the determination of optimal extended coherent integration time and non-coherent accumulations allowing the achievement of pre-defined acquisition metrics will be presented and then validated by means of simulations. Complete data navigation bits and secondary code synchronization achieved thanks to the use of external aiding sources or self-assistance techniques is considered along the analysis which will provide results for weak GNSS signal acquisition in the GPS L1/L5 and Galileo E1/E5 frequency bands. Presence of a Doppler aiding source is considered and a detailed study on the required Doppler aiding accuracy is also presented.