# Preparations for Galileo PRS in Poland
## 5 Polish Contribution for the PRS
### GNSS Jamming Tests in a Controlled Laboratory Environment
* INT5, Pulse--the rapid increase of the signal amplitude from a baseline value to a higher value, followed by a rapid return to the baseline value, with 1 us impulse length and different repetition periods in the range of 20 ms to 2 us,
* INT6, Sweep (linear chirp)--the constant amplitude signal, in which the frequency increases over 100 us time, with 5 kHz, 10 kHz or 20 kHz steps in a 4 MHz bandwidth, from 1573.47 (L1 \(-\) 2 MHz) to 1577.47 MHz (L1 + 2 MHz). The first part of the test was performed for the static scenario and the second for the dynamic one. At the beginning of each test, the actual GNSS signal level at the output of the L1/L2 amplifier (in the case of static tests) or at the high-power output of the GNSS Constellation Simulator (in the case of dynamic tests) was measured (with respect to the 4 MHz channel) to obtain the proper C/I (carrier-to-interference ratio) for further jamming tests. The detailed analysis of the collected measurement results was conducted using the RTKPOST application, a part of the RTKLIB library [8]. The receiver position was determined using the Single positioning method in the L1/E1 bands, using only the Galileo or GPS system. On the basis of the static test and for the purpose of the dynamic test, two smartphones with the best and worst resistance to jamming were identified, and three types of the most harmful jamming signals were used. The dynamic scenario was designed in compliance with technical specification 3 GPP TS. 25.171 [9], which defines a test case to verify the receiver's capability to produce GPS measurements or location fixes in a vehicle that is moving, slowing down, accelerating and turning. In both cases (static and dynamic), the detailed statistical analysis was conducted, aimed at the quality of the determined position based on the accuracy and precision measures with respect to the high-accuracy reference RTK position of the rooftop antenna in the case of static tests and the reference route for dynamic tests. For further comparative analysis, the R95 measure (radius of the circle with the center in the actual position, which covers 95% of the measurements) was chosen as one of the most frequently used [10,11]. The Dilution of Precision (DOP) parameters were also observed. On the basis of the measurement results, the so-called C/I cut-off level and C/I degradation level were determined for most types of interference:  
* The C/I cut-off level was defined as the highest C/I ratio, for which the transition from the \"3D fix\" state to the \"no-fix\" state was observed. * The C/I degradation level was the highest C/I ratio, for which the accuracy (related to the reference RTK position in the case of static tests and the reference route for dynamic tests) starts to exceed the value of 15 m.  
Tables 2 and 3 present the interferences' impact levels for the smartphones tested in the Galileo and GPS scenarios for the static and dynamic tests, respectively. INT1 (Continuous Wave), the simplest interfering signal, had a minor impact on most of the tested smartphones, especially for the GPS scenario. As the interference level was increased, the corresponding degradation of the decoded signal quality in the receiver (denoted as the SNR level) could be observed. The degradation rate was more rapid for the GPS than for Galileo. Further, the DOPs values were affected, which could be seen as gradual or abrupt deterioration or significant fluctuations. The most significant impact was noticed for the Samsung smartphone (for both Galileo and GPS), in which case the interferer caused almost complete degradation of the received signal from the beginning of the jamming signal occurrence. The Google and Sony smartphones were only affected when working with the GPS. In the presence of the INT1, no smartphones, except for Samsung, lost their ability to determine their position using Galileo signals. In fact, the Huawei was so resilient that even at high levels of INT1, it was still able to determine its position.