A fast method for the acquisition of weak long-code signal
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ORIGINAL ARTICLE
A fast method for the acquisition of weak long‑code signal Guanghao Nie1 · Xinlong Wang1 · Liangliang Shen2 · Yuanwen Cai3 Received: 4 April 2020 / Accepted: 30 July 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract The growing demand for positioning, navigation and timing services is boosting the development of new signal systems that are gradually being adopted by Global Navigation Satellite System (GNSS), such as the BDS, the Galileo and the modernized GPS. A common feature of these new signal systems is that they have longer pseudorandom noise (PRN) code lengths than the old ones, which greatly improves the ranging accuracy and anti-interference ability of signals. However, the longer PRN code length leads to increased computational complexity and reduced acquisition speed, especially in low-carrier-tonoise-ratio (CNR) conditions. A rapid scheme for the acquisition of weak long-code signal is proposed. The reduced Doppler shift and code-phase space are pre-estimated with inertial navigation system (INS) aiding and ephemeris, and an FFT-based parallel time–frequency domain search method is used to realize rapid two-dimensional search. To further reduce the computational complexity of weak long-code signals, a parallel code-phase search (PCS) method with reduced code-phase space based on matrix partition and reconfiguration is proposed inside the correlator, which can realize the rapid coherent operation of signals. The proposed algorithm can greatly reduce the theoretical operands of FFT operation in the acquisition without loss to the relevant peak, to meet the requirements of receiver sensitivity and acquisition speed in the low-CNR conditions. Finally, computer simulations verify the effectiveness of this acquisition scheme. Keywords Low carrier-to-noise ratio · Long-code signal · Parallel search · Reduced code-phase space · Matrix partition and reconfiguration
Introduction With the growing demand for positioning, navigation and timing services, the global navigation satellite system (GNSS) community is gradually adopting several new system signals to improve ranging accuracy and * Xinlong Wang [email protected] Guanghao Nie [email protected] Liangliang Shen [email protected] Yuanwen Cai [email protected] 1
School of Astronautics, Beihang University, Beijing 100083, China
2
Beijing Institute of Control and Electronic Technology, Beijing 100038, China
3
Department of Graduate School, Space Engineering University, Beijing 101416, China
anti-interference performance, such as B1C and B2a signals of BD3, E1, E5a and E5b signals of Galileo, and L1C and L5 signals of modernized GPS. Compared with the early GNSS signals, these new system signals have the following characteristics (Leclere et al. 2014). The PRN code length is increased, which improves autocorrelation and crosscorrelation performance of the signals, and the acquisition gain and anti-interference ability of the signals are improved. The pilot channel without carried navigation data is introduced, wh
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