# Method for Estimating the Optimal Coefficient of L1C/B1C Signal Correlator Joint Receiving
## 6 Conclusions  
This paper discusses combining-coefficients of the correlator joint receiving algorithm for unequal power signals. Based on the equivalence principle of correlator joint and discriminator joint, the optimal coefficient of carrier loop is determined as an amplitude ratio. By establishing the mathematical model of the code tracking accuracy of the correlator joint, the optimal coefficient of the code loop is determined as the amplitude ratio joint. In this paper, we adopted is the two-quadrant arctangent discriminator and the non-coherent early-minus-late amplitude discriminator. Finally, the real-life satellite signal is used to analyze the receiver loop output and positioning accuracy. The experimental results are consistent with the theory model's prediction. The results show the following.  
For the modulation signal with unequal power for the data and pilot, the \"amplitude ratio combination\" is the optimal solution. It has the smallest loop error standard deviation, the most concentrated distribution of the positioning results, and the highest positioning accuracy, followed by the power ratio combination and, finally, the traditional 1:1 combination.  
The C/N0 of the B1C(L1C) correlator joint signal is 6 dB higher than that of the data component and 1.3 dB higher than that of the pilot component. Most importantly, the C/N0 in the \"amplitude ratio combination\" is approximately 0.2 dB higher than that in the 1:1 combination.  
The \"amplitude ratio combination\" of the B1C signal and the L1C signal can be improved by 11.5% and 14.4% relative to the pilot component positioning. It is worth mentioning that the positioning accuracy of the amplitude-ratio combination is improved  
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline
**Signal** & **3/1(\%)** & **4/1(\%)** & **5/1(\%)** & **3/2(\%)** & **4/2(\%)** & **5/2(\%)** & **5/2-3/2(\%)** & **5/2–4/2(\%)** \\ \hline B1C & 41.265 & 41.727 & 42.560 & 9.434 & 10.147 & 11.431 & 2 & 1.3 \\ \hline L1C & 45.417 & 45.886 & 46.886 & 12.001 & 12.765 & 14.377 & 2.37 & 1.6 \\ \hline \hline \end{tabular}
\end{table}
Table 6: The positioning accuracy improvement ratio in the ECEF coordinate system.  
by 2% compared to the 1:1 combination, and by 1.3% compared to the power-ratio combination for BIC signal. The positioning accuracy of the amplitude-ratio combination is improved by 2.37% compared to the 1:1 combination, and by 1.6% compared to the power-ratio combination for L1C signal.  
In summary, when performing correlator joint reception for data and pilot component, it is recommended that the user chooses the amplitude-ratio combination method to maximize the combined positioning effect. In the future, we will further study whether the method used in this article is suitable for the joint reception of other dual signals in GNSS.  
Conceptualization, D.Z. and X.W.; methodology, Y.G.; software, Y.G. and X.W.; validation, Y.G. and Y.R.; formal analysis, Y.G. and Y.R.; resources, Y.G. and P.S.; data curation, Y.G. and Z.C.; writing--original draft preparation, Y.G.; writing--review and editing, X.W. and D.Z.; project administration, D.Z. and X.L. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the National Natural Science Foundation of China (grant number 41974032), and the Natural Science Foundation of Shanxi province, China (grant number 2021 JM-323).  
Not applicable.  
The data that support the findings of this study are available from the corresponding author upon a reasonable request.  
The authors declare no conflict of interest.