Signal Parameter Estimation and Demodulation of the OneWeb Ku-Band Downlink

We present techniques for estimating key parameters of OneWeb's Ku-band downlink signal (10.7--12.7 GHz) and reveal it as a single-carrier QPSK signal with a 230.4 MHz symbol rate. The techniques also estimate the signal's roll-off factor and center frequencies. We further provide the first published account of OneWeb signal demodulation, revealing the basic frame structure of the downlink signal, including a synchronization sequence that repeats every millisecond and is common across all beams, channels, and satellites. Identifying this sequence enables making time-of-arrival measurements from OneWeb signals. These findings contribute to the growing body of research focused on repurposing low-Earth-orbit satellite communication signals for positioning, navigation, and timing.