Acquiring GNSS Signals in Cislunar Space: A Hardware-in-the-Loop Investigation for LuGRE Mission Data

The use of Global Navigation Satellite System (GNSS) signals in cislunar space is gaining interest as a means to enhance navigation autonomy for lunar missions. This work investigates the acquisition of GNSS signals in this challenging environment, using a dataset obtained leveraging a hardware-in-the-loop experimental setup including the QN400-SPACE GNSS receiver and a Radio Frequency Constellation Simulator (RFCS). The study focuses on the processing of short batches of signals in the low-fidelity operating mode, characterized by a constrained sampling frequency and quantization levels. To enhance acquisition sensitivity, we explore various techniques, including Doppler compensation on the spreading code and exhaustive bit search strategies. Experimental results demonstrate the impact of Doppler correction on improving correlation peak sharpness and increasing successful acquisitions. This work establishes a baseline for testing high-sensitivity acquisition techniques on actual mission data once they are publicly released to the GNSS community, contributing to the advancement of GNSS-based navigation solutions for future lunar and deep-space exploration missions.