C/N0 Estimation Based on Acquisition Correlation Ratio for Short GNSS Data

Carrier-to-noise ratio (C/N0) represents the ratio of signal power and noise power density, and it is of great significance in many applications of Global Navigation Satellite System (GNSS), such as satellite signal quality monitoring, spoofing detection, position accuracy estimation, etc. Accurate C/N0 estimation results will benefit a lot for short data situations like snapshot receivers, fast spoofing detection, adjusting tracking loop parameters based on fast C/N0 estimation and so on. However, most classical C/N0 estimation methods rely on the tracking stage of a GNSS receiver, which requires at least seconds of data to get an accurate estimation and further limits the application of C/N0 for such situations. To address the limitations of C/N0 estimation for short GNSS data, we introduce a C/N0 estimation method based on the Acquisition Correlation Ratio (ACR) that estimates C/N0 within only a few milliseconds signals. We derive the theoretical performance of ACR and three classical C/N0 estimation methods. It can be proved that the proposed ACR method has lower theoretical RMSE than the other three methods. Monte Carlo simulations are consistent with the theoretical analysis, which indicates that the accuracy of ACR method can approach the theoretical bound. Experiment results of signal simulator test and real-world test both indicate that the proposed method can enhance the estimation accuracy of C/N0 under short data conditions, achieving an estimation RMSE improvement of 0.8 dB-Hz on average with 20 ms data.