# Characterization of Carrier Phase-Based Positioning in Real-World Jamming Conditions
## 4 Analysis and Results
### Analysis 2: Code versus Carrier Phase Positioning Performance  
The purpose of this analysis is to evaluate the performance of code versus carrier phase-based positioning. Following up on the first analysis, this is a comparison of the reliability of code and phase positioning solutions during jamming. For this analysis, only jamming Case 3 is used because it is a relatively light incident. This is the only case where a sufficient number of interference-affected satellites are tracked throughout the incident. Thus, for Case 3, a differential GPS (DGPS) and a kinematic PPK float solution are determined using SVs G07, G10, G16, G20, G21, G26, and G27--all satellites that are affected by jamming while the tracking is not lost. As Case 3 is a single-frequency case, only L1 data are used for the solutions. To avoid initialization obscuring the PPK solution (and because of the fact that hourly files are used), the positioning solution is calculated for the entire two hour period, 19:00-21:00. Baseline 1 of Table 3 is used. This is a 4.1 km baseline with the jammed station TA03 as a base, and in this specific analysis, the RTKLIB software is used for the calculations. Figures 8 and 9 show residuals and horizontal baseline components for both the DGPS and PPK float solutions. Table 4 shows standard deviations (std) of those solutions both during the jamming incident and during a similar clean period. Figure 7: Signal tracking and cycle slips (marked in red) for all three cases. From the left, Case 1, Case 2, and Case 3 on the far right. The red boxes mark the jamming incident, with approximate times displayed at the top. Color coding of the tracking lines indicates available signals: Green = L1 + L2, Blue = L1 + L2 + L5, Yellow = L1 only, Pink = L2 only. Figure 8: Residuals per satellite in a DGPS (top) and PPK float (bottom) solution for Case 3, baseline 1 (4.1 km) using only L1 data from select satellites (G07, G10, G16, G20, G21, G26, and G27). Red arrows mark the start and end of the jamming incident. Notice the different scales on the y-axis. Figure 9: East and north components of the baseline vector for the DGPS (top) and PPK float (bottom) solutions in Case 3, baseline 1, using only L1 data from select satellites (G07, G10, G16, G20, G21, G26, and G27). Red arrows mark the jamming interval. Note the meter-level zoom on the y-axis in the top plot, and cm-level zoom in the bottom plot. From Figure 8, it is seen that both code and carrier phase residuals are affected by jamming, and it is not immediately clear that the carrier phase-based solution would be less affected by jamming. However, as shown in both Table 4 and Figure 9, jamming has very little impact on the carrier phase-based PPK float solution, while the DGPS solution is affected by noise. This may be because of the fact that a float solution in general is much more precise than a code-based DGPS solution, and that a small amount of noise, therefore, could result in a much larger impact on the DGPS solution. Looking at the y-axis of Figure 8, for instance, it is seen that the jamming only increases the carrier phase residuals by a few mm, while it translates into decimeters/meters on the code. In general, this indicates that positioning solutions based on the carrier phase is the more robust and safer option during jamming. The standard deviation of the float solution is actually better during jamming than during the clean period. As seen in Figure 8, this is a matter of circumstances, as two low elevation satellites (G07, G10) are the primary reason for increasing the standard deviation (std) of the float solution in the period leading up to the jamming incident. These results support the conclusions of Analysis 1--that if a satellite is tracked by the receivers, it may be used in a reliable carrier phase positioning solution. _Summary. Observations affected by jamming have almost zero influence on carrier phase-based positioning precision.