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BeiDou Signal Acquisition with Neumann-Hoffman Code Modulation in a Degraded Channel
Lin Zhao1, Aimeng Liu2, Jicheng Ding3
1Harbin Engineering University, College of Automation, Harbin 150001, China. zhaolin@hrbeu.edu.cn.
Sensors (Basel, Switzerland)
|February 18, 2017
Summary
This study introduces a new algorithm to improve Global Navigation Satellite System (GNSS) signal acquisition, specifically for weak BeiDou Navigation Satellite System (BDS) signals. The method enhances frequency accuracy and detection probability by addressing challenges posed by Neumann-Hoffman (NH) codes.
Area of Science:
- Satellite Navigation Systems
- Signal Processing
- Geodesy
Background:
- Modern Global Navigation Satellite Systems (GNSS) utilize secondary codes, Neumann-Hoffman (NH) codes, to enhance positioning performance.
- Frequent bit transitions in NH codes degrade the acquisition sensitivity of traditional integration algorithms.
- Weak BeiDou Navigation Satellite System (BDS) signals are particularly susceptible to these acquisition challenges.
Purpose of the Study:
- To analyze the detrimental effect of NH codes on signal acquisition, particularly for weak BDS signals.
- To develop a novel algorithm that mitigates the negative impact of NH codes on acquisition sensitivity and frequency accuracy.
- To improve the carrier-tracking loop initialization and code phase acquisition accuracy.
Main Methods:
- Detailed analysis of the side effects of NH codes on signal acquisition.
- Derivation of a formula quantifying the decrease in frequency accuracy due to bit transitions.
- Proposal of a frequency recalculation algorithm utilizing Fast Fourier Transform (FFT) and differential correction.
Main Results:
- The derived formula confirms that NH code bit transitions reduce frequency accuracy.
- The proposed algorithm effectively mitigates the adverse effects of NH codes.
- Simulations and real BDS data tests show superior detection probability and frequency accuracy compared to conventional methods in degraded channels.
Conclusions:
- The developed frequency recalculation algorithm significantly improves the acquisition of weak GNSS signals, especially BDS.
- The integration of FFT and differential correction offers a robust solution for enhanced positioning performance.
- This approach addresses a critical limitation in current GNSS signal processing, paving the way for more reliable navigation.
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