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Session A5: Receivers for New Space-Based Sources

Weak Signal Acquisition and Tracking of the Starlink Ku-Band Downlink to Enable Global PNT
Zacharias M. Komodromos, Wenkai Qin, Todd E. Humphreys, Department of Aerospace Engineering and Engineering Mechanic, The University of Texas at Austin
Location: Ballroom C
Alternate Number 1

We explore and characterize the limits of weak signal acquisition and tracking of the Starlink Ku-band downlink signal. An ability to acquire and track signals whose signal-to-noise ratio (SNR) is below 0 dB unlocks possibilities for use of Starlink as a global position, navigation, and timing (PNT) system without modification. We extend work characterizing the Starlink signal structure with additional synchronization sequences and observations of a semi-fixed structure within the Starlink downlink frame. By exploiting all the known repeating structure in the Starlink signals, we are able to extract time of arrival measurements at SNR values far below those required for communication. Such improved sensitivity may enable tracking signals from Starlink satellites whose beams are directed at service cells other than where the Starlink PNT receiver is located, thus enabling instantaneous multilaterated PNT. We validate published theoretical SNR bounds for Starlink signal acquisition against experimental results. We also show that near perfect knowledge of a single frame’s full content enabled experimental signal acquisition below -20 dB SNR on a captured frame.

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