Combined Acquisition and Tracking Methods for GPS L1 C/A and L1C Signals

Abstract

As part of the GPS modernization, the GPS L1 C/A signal will be augmented by the L1C signal. With this improvement, for the first time, several signals from the same constellation will be available at the same frequency. In this paper, an acquisition method is implemented to combine the GPS L1 C/A and L1C signals before correlation. The combined acquisition succeeds to acquire the signal at low C/N 0 , whereas the acquisition of the L1C data channel alone fails. Concerning the tracking, a method to combine the GPS L1 C/A and L1C signals before the discriminator is developed. This method shows better performance than the traditional tracking using only one signal. Finally, a Kalman filter to combine the signals in the tracking is developed. It shows better performance than the traditional tracking in all conditions. Since the L1C signal will not be broadcast before 2013, these methods are tested using a software signal simulator.

Tuning a Kalman filter carrier tracking algorithm in the presence of ionospheric scintillation

“…AKF1 is a classical adaptive KF tracking with Q a priori fixed, as in Macchi-Gernot et al (2010), and with the elements of R obtained as in (11) and (12). AKF2 has the same characteristics as AKF1, but additionally, it applies the scaling factor to R as shown by Eq.…”

“…Traditionally, in order to define the above matrices, the dominant error contributions are taken into account as in Macchi-Gernot et al (2010). Under the assumption of uncorrelated noise sources Q, which is the continuous version of Q k in (14), can be defined as a diagonal matrix with the diagonal elements given by the spectral densities of each processes noise S Ds S Du S Df S Da ½ .…”

“…Under the assumption of uncorrelated noise sources Q, which is the continuous version of Q k in (14), can be defined as a diagonal matrix with the diagonal elements given by the spectral densities of each processes noise S Ds S Du S Df S Da ½ . The relationship between continuous and discrete domain can be found in Macchi-Gernot et al (2010). S Ds represents the power spectral density of the carrier/code divergence, which is produced by propagation through the ionosphere.…”

“…The approach is justified by the theoretical relationship between Phi60, p and T defined in (3). S Ds and S Da are kept constant and modeled as in Macchi-Gernot et al (2010).…”

Design and implementation of a real‐time software receiver for BDS‐3 signals

“…An L1 C/A‐aiding method to acquire the L2C signal was proposed in the study of Lim . Combined acquisition methods for L1 C/A and L1C signals were proposed in previous studies . These methods utilize the strong correlations between the signal with short ranging code and the signals with long ranging codes from the same satellite.…”