<i>C/N₀</i> Estimator Based on the Adaptive Strong Tracking Kalman Filter for GNSS Vector Receivers

• Main Authors: Shiming Liu, Sihai Li, Jiangtao Zheng, Qiangwen Fu, Yanhua Yuan
• Format: Article
• Language: English
• Published: MDPI AG 2020-01-01
• Series: Sensors
• Subjects: global navigation satellite system (gnss); vector tracking loops; carrier-to-noise ratio; strong tracking kalman filter
• Online Access: https://www.mdpi.com/1424-8220/20/3/739

The carrier-to-noise ratio (<i>C/N₀</i>) is an important indicator of the signal quality of global navigation satellite system receivers. In a vector receiver, estimating <i>C/N₀</i> using a signal amplitude Kalman filter is a typical method. However, the classical Kalman filter (CKF) has a significant estimation delay if the signal power levels change suddenly. In a weak signal environment, it is difficult to estimate the measurement noise for CKF correctly. This article proposes the use of the adaptive strong tracking Kalman filter (ASTKF) to estimate <i>C/N₀</i>. The estimator was evaluated via simulation experiments and a static field test. The results demonstrate that the ASTKF <i>C/N₀</i> estimator can track abrupt variations in <i>C/N₀</i> and the method can estimate the weak signal <i>C/N₀</i> correctly. When <i>C/N₀</i> jumps, the ASTKF estimation method shows a significant advantage over the adaptive Kalman filter (AKF) method in terms of the time delay. Compared with the popular <i>C/N₀</i> algorithms, the narrow-to-wideband power ratio (NWPR) method, and the variance summing method (VSM), the ASTKF <i>C/N₀</i> estimator can adopt a shorter averaging time, which reduces the hysteresis of the estimation results.