# Preparations for Galileo PRS in Poland
## 5 Polish Contribution for the PRS
### GNSS Jamming Tests in a Controlled Laboratory Environment  
For the purpose of the jamming test within the 3 PfD project, a high-flexibility measurement station has been designed and developed, taking advantage of the NIT's experience in that field. The tests goal was to evaluate the interference resistance of GNSS receivers in smartphones (as one of the GNSS commercial solutions). To avoid live GNSS signals coming directly to the testing environment and also to prevent jamming signals from leaking outside the laboratory, the isolated measurement location in the basement of the NIT's office was selected for the purpose of the jamming tests. For the purpose of testing, a high-flexibility measurement station (presented in Figure 5) has been developed, which consists of (the key elements):  
* GNSS Constellation Simulator (Spinent GSS7000),
* Reference GNSS RTK Receiver (GINTEC M1G2),
* Vector signal generator (Agilent N5182A),
* SDR Platform (National Instruments USRP-2945R),
* Spectrum analyzers (Keysight N9914A, Anritsu MS2721B),
* Different smartphones from various manufacturers capable of GNSS raw measurements,
* Computer with the measurement applications. Live signals from the active GNSS antenna (installed on the building's rooftop), amplified with a low-noise amplifier (LNA) or artificial signals from a GNSS Constellation Simulator, were combined with the jamming signals and then transmitted by the GNSS passive antenna. In each step, the signals were measured by the spectrum analyzers. A reference position of the rooftop antenna has also been obtained using the GNSS RTK  
Figure 4: Histogram of the detected interference duration time in the E1 and E6 bands in Poland. receiver, which facilitated the position determination accuracy tests in the presence of jamming. The campaign was conducted in 2019 and 2020 using different manufacturers' top-market (at that time) Galileo-compatible smartphones featuring GNSS raw measurements capabilities. In practice, though, due to some compatibility problems with the raw measurements, a dedicated Android Measurement App had to be developed by the NIT on the basis of [7]. This application allowed logging the NMEA data with basic GNSS parameters, satellite status and all the available raw measurements of the GPS and Galileo in the L1/E1 and L5/E5 frequency bands, and to subsequently create RINEX data on their basis. The NIT also developed the PC Measurement Application, which allowed controlling the Android Measurement App on all smartphones via USB connection, to perform simultaneous measurements on all smartphones and to collect the logged data. During the tests, all the smartphones were switched to Airplane mode in order to avoid the Assisted GNSS mode activation, which could affect the results. After initial tests, some of the smartphones had to be excluded from further stages due to problems with raw data logging. Ultimately, the jamming tests were performed on four types of smartphones: Google Pixel 3 XL, Huawei Mate 20 Pro, Samsung Galaxy S9+ and Sony Xperia XZ3. For the purpose of the jamming test, we created a large library of interfering signals featuring various interference mechanisms, occupying different bandwidths and exhibiting various time characteristics. After the initial analysis of several variants, it was decided that six general interference signals would be considered in further tests:  
* INT1, Continuous wave (unmodulated carrier)--the single sine wave with constant amplitude and frequency, centered at L1 = 1575.42 MHz;
* 1 MHz), 1575.42 MHz (L1) and 1576.42 MHz (L1 + 1 MHz),
* INT3, Wideband AWGN signal--the Additive White Gaussian Noise in the 60 MHz bandwidth covering the L1/E1 and G1 GNSS bands,
* INT4, Narrowband modulated carrier--the QPSK-modulated signal with 4 MHz bandwidth,  
Figure 5: Jamming test measurement station.