Previous Abstract Return to Session C3 Next Abstract

Session C3: Signals of Opportunity-Based Navigation Systems 1

A Multi-Stage Long Coherent Integration Approach to Detect LEO Debris Scattered GNSS Signal: Experimental Results
Md Sohrab Mahmud, Edwin G. W. Peters, University of New South Wales; Craig R. Benson, Skykraft Pty Ltd.; Andrew Lambert, University of New South Wales
Location: Big Sur
Alternate Number 1

The increasing amount of space debris in Earth's orbit represents a potential threat to active satellites and spacecraft. Kessler syndrome suggested that new collisions could exponentially increase the amount of debris, increasing the level of danger represented by these objects. Monitoring the space environment is necessary to prevent further collisions with active satellites. Observing objects in the Low Earth Orbit (LEO) regime is crucial to avoid collisions. In this paper, we extend aspects of the demonstration of tracking space debris in Low Earth Orbit using signals of opportunity from GNSS satellites. The wavelengths of GNSS signals are in the order of 20 cm, and our primary focus is to track debris smaller than this. However, the signals scattered by debris at the terrestrial receiver will be weak. Thus, it requires a computationally expensive, long coherent integration over an extended period. Detection of weak signals requires extensive signal processing gain to surpass the noise floor and other interference. This study demonstrates an approach to detecting the scattered GNSS signals to characterize objects in the LEO using an onboard GPS receiver recording data from M2 CubeSats. Under reasonable assumptions, coherent integration can raise the desired signal above the noise floor. We break down the acquisition process into two stages: a coarse acquisition and a fine Doppler search to handle the computationally expensive operation associated with long coherent integration. We highlight the replica regeneration based on retrieving the estimated phase at an affordable phase measurement method. Also, a demonstration of desired processing gain through re-acquisition in the presence of significant and time-varying Doppler shifts is presented.



Previous Abstract Return to Session C3 Next Abstract