Binomial Harmonic Approximation Double-Phase Estimator Tracking for BOC Modulated Signals

For binary offset carrier (BOC) signal tracking, the Two-Dimensional (2D) tracking method that independently tracks the code and subcarrier has garnered significant attention. The double estimator (DE) and the double phase estimator (DPE) are prominent approaches. However, the performance of the DE suffers under limited front-end bandwidths and sampling rates. The DPE, which treats the subcarrier as a sine wave, neglects side lobes, leading to performance degradation. This letter introduces the Binomial Harmonic Approximation DPE (BH-DPE), which uses two phase lock loops to track the first and third harmonics of the subcarrier. By applying a weighted combination of correlation values, the BH-DPE effectively reduces coherent output signal-to-noise ratio (SNR) loss and enhances ranging accuracy through combined delay estimations from both the harmonics. Theoretical analysis and simulations show that the BH-DPE outperforms both the DE and the DPE in terms of SNR loss and ranging accuracy under constrained front-end bandwidths and sampling rates, and approaches the DE while exceeds the DPE under wide front-end bandwidths.