## 5 Discussion and Conclusions  
The zero-baseline experiments were used to evaluate the GNSS positioning performance. This paper presents a method to figure out the accuracies of BDS-3 new civil ranging codes directly using the data collected from a zero-baseline experiment. The results show that the B2a code ranging accuracy is better than that of BIC, and similarly with GPS L5C code.  
About 7 h of raw IF data were collected on two frequencies. For a certain frequency point, at least one hour of data were selected for processing. The final calculation results show that the precision of the new civil signal BIC is in correspondence with B2a, while BIC has a larger STD value. The difference between B2a and BIC signal structures has a great impact on the ranging accuracy. B2a has a higher code rate, so it has higher ranging accuracy. Although BIC has a wide bandwidth, its accuracy is reduced due to its slow code rate. At the same time, compared with GPS signals, it can be found that B2a and LSC have similar ranging accuracy, owing to the same code rate and code length. In addition, the dispersion of the ranging results has weak negative correlation between satellite elevations when the satellite elevation meets \(30^{\circ}\) to \(90^{\circ}\), for which the Pearson correlation coefficient is \(-0.308\). Under the condition of high satellite elevation, the data onto one second have a relatively small STD value, that is, higher ranging accuracy.  
In this work, the amount of the raw IF data storage is too large, and the speed of processing the data using the GNSS-SDR software receiver is too slow. We only processed and analyzed parts of the data in the environment with good weather and an open surrounding area. The analysis of this work only involves the B2a and BIC signals of BDS-3 with the L5 signal of GPS. Therefore, we also plan to compare the ranging performance of each frequency band signal of other GNSSs in future work to expand the universality of the conclusion.  
Conceptualization, Y.L. ([PERSON]) and F.G.; data curation, Y.L. ([PERSON]), J.L., Y.L. ([PERSON]) and Y.Q.; formal analysis, Y.L. ([PERSON]); funding acquisition, F.G.; investigation, Y.L. ([PERSON]), J.L., B.N., Y.L. ([PERSON]) and Y.Q.; methodology, Y.L. ([PERSON]); project administration, F.G.; resources, Y.L. ([PERSON]); software, Y.L. ([PERSON]), J.L., B.N. and S.C.; supervision, F.G.; validation, Y.L. ([PERSON]), J.L., Y.L. ([PERSON]) and Y.Q.; visualization, J.L.; writing--original draft, Y.L. ([PERSON]); writing--review and editing, F.G., J.L. and Y.H. All authors have read and agreed to the published version of the manuscript.  
This research was funded by Wenhai Program of the S&T Fund of Shandong Province for Pilot National Laboratory for Marine Science and Technology (Qingdao) (NO.2021 WHZZZB1004) and the Program of the National Natural Science Foundation of China, (grant number 41604003, 41704017).  
The data used in the experiment are managed by the Institute of Space Science of Shandong University, and the author can be contacted to obtain the experimental data.  
**Acknowledgments:** The author thanks the satellite navigation and remote sensing research group of the Institute of Space Science of Shandong University for its site and technical support.  
**Conflicts of Interest:** The authors declare no conflict of interest.