An FLL structure based on a DFT interpolation discriminator for tracking weak GNSS signal

  • Cheng Li
    Dept. of Physics, Mechanical and Electrical Engineering, Hubei University of Education

抄録

<p>In a GNSS receiver, carrier tracking is the most challenging part, especially in a harsh environment. This paper presents an open tracking loop structure to overcome the matter of losing lock under weak-signal conditions. In order to enhance the stability and sensitivity of weak GNSS signal tracking, a frequency-locked loop structure based on DFT interpolated frequency estimation is proposed. The IF signals are split into two branches in the structure, and each signal is correlated with an equally frequency-spaced local carrier. Then, a new DFT interpolation algorithm of two-point DFT interpolation is used as a frequency discriminator to calculate the carrier frequency deviation. The bias and RMSE performances of the frequency discriminator are comparatively analyzed under different SNRs using computer simulations. Simulation results show that this discriminator is characterized by small computational effort and high estimation accuracy. The signal-tracking performances of the structure are verified by an experiment using a GNSS simulator. Results demonstrate that this method is able to track 26dB-Hz signals using only 8 samples, which improves the tracking threshold by 4dB-Hz over the FFT discriminator, and its tracking error jitter is less than 0.5Hz. The structure needs only two-point interpolation, resulting in a low computation load in a real-time receiver.</p>

収録刊行物

  • IEICE Electronics Express

    IEICE Electronics Express 21 (7), 20240068-20240068, 2024-04-10

    一般社団法人 電子情報通信学会

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