## 4 Data Set Examples  
In this section we present sample data acquired and processed with the SPIR instrument and software processor in an airborne experiment over the Baltic Sea at a 3000 m altitude in December 2015.  
Figure 13 shows example power waveforms obtained when using clean-replica processing for each antenna element individually, employing a coherent integration time of 1 ms and a non-coherent integration of 1 s. The upper row corresponds to the eight up-looking antennas and the lower row for the down-looking ones, and from left to right GPS L1, Galileo E1 and GPS L5, using the corresponding publicly available chipping codes. The shape of the obtained waveforms is consistent with theory, and only amplitude variations, which are caused by gain and noise figure variability among receiver channels, can be observed. For GPS L1, we can clearly appreciate the shape of the C/A waveform. For Galileo E1, the waveform has a more complex shape due to the sub-carrier modulation. For GPS L5, the waveform is much narrower than for the previous two cases (note the different horizontal axis in the plot), as the chipping rate is 10.23 MHz instead of 1.023 MHz. The SNR values for the different waveforms are shown in the caption of the figure.  
Figure 14 shows the obtained waveforms after beamforming for the up and down-looking antenna arrays. The first row corresponds to the clean-replica waveforms obtained by the up-looking antenna array, while the second row corresponds to the clean-replica waveforms obtained using the down-looking antenna array. The third row shows the waveforms obtained using the interferometric  
Figure 13: Clean-replica power-waveform examples by channels. (**a**) Power-waveforms of the up-looking channels (CH01\(\sim\)CH08). From left to right: GPS L1 (SNR = 16.9\(\sim\)20.1 dB), GALILEO E1 (SNR = 19.4\(\sim\)21.1 dB), and GPS L5 (SNR = 17.4\(\sim\)19.0 dB). (**b**) Power-waveforms of the down-looking channels (CH09\(\sim\)CH16). From left to right: GPS L1 (SNR = 13.3\(\sim\)15.3 dB), GALILEO E1 (SNR = 8.6\(\sim\)12.4 dB), and GPS L5 (SNR = 8.9\(\sim\)10.2 dB).  
technique. Again, from left to right, the waveforms correspond to GPS L1, Galileo E1, and GPS L5 acquisitions. The coherent and non-coherent integration times were 1 ms and 1 s, respectively. The obtained waveforms are coincident with the expected ones also in this case. It can be clearly observed that the resulting waveforms for GPS L1 are much narrower than for the clean-replica processing, as the full bandwidth of the transmitted signals is used, including the P and M chipping codes. For Galileo E1, we can also observe the _ripples_ on top of the waveforms, whose origin is the Galileo E1-A code, which has a sub-carrier modulation.  
Figure 14: Power-waveform examples after beamforming. (**a**) Up-looking clean replica power-waveforms after beamforming. From left to right: GPS L1 (\(SNR=24.9\) dB), GALILEO E1 (\(SNR=28.5\) dB), and GPS L5 (\(SNR=27.0\) dB). (**b**) Down-looking clean replica power-waveforms after beamforming. From left to right: GPS L1 (\(SNR=20.8\) dB), GALILEO E1 (\(SNR=18.1\) dB), and GPS L5 (\(SNR=17.7\) dB). (**c**) Interferometric power-waveforms after beamforming. From left to right: GPS L1 (\(SNR=8.6\) dB), GALILEO E1 (\(SNR=9.9\) dB), and GPS L5 (\(SNR=8.7\) dB).  
The presented results show that the instrument is capable of adequately acquiring and processing the signals with proper beamforming, and obtaining waveform observables using the clean-replica and interferometric processing methods indistinctly.