# Low-Cost _Ka_-Band Satellite Receiver Data Preprocessing for Tropospheric Propagation Studies
## 3 Results
Now, we go on to present a case, also often observed, with possible condensation on the antenna's radome taking place. Figure 10 shows the same plot as in Figure 5, now for 17 August 2018. Here, we observe a strange artifact in the extracted template with a drop of a few tens of one dB during the early hours of the day, before and during sunrise. This drop then disappears, and the normal daily cycle is resumed. In this case, the correlation with the ambient temperature was \(-0.41\). We can see that this strange episode took place during a period of time when the ambient temperature was close to the dew point. We assumed that this effect was probably caused by condensation on the antenna's radome. Furthermore, we have a look at the dependency between template and relative humidity (\(RH\)) in Figure 11. We can see that the level dip corresponds to a period with significant \(RH\), close to 100%, consistent with the condensation hypothesis. In clear-sky days, as in Figure 6, the \(RH\) is usually much smaller. Figure 10: Template, ambient temperature, and dew point for a clear-sky day with possible condensation on the radome: 17 August 2018. Figure 3:0 Ambient temperature for the days in August 2018 with all full-day clear sky. Days: 2-5, 10–11, 15, 18–20, 23, 26, and 31. Finally, we looked at the recordings from 3 November 2018. This was a very cloudy day with no rain. Again, Figures 12 and 13 illustrate the template and the concurrent local meteorological parameters. From the METAR files, it was obtained that the eight oktas of the sky were covered throughout the day (8/8 of sky completely overcast, no breaks or openings). Figure 3:1 Template and relative humidity for a clear-sky day with possible condensation on the radome: 17 August 2018. Figure 3:2 Template, ambient temperature, and dew point for a cloudy-sky day: 3 November 2018. Figure 3:3 Template and relative humidity for a cloudy-sky day: 3 November 2018. On this cloudy day, the template excursion was around 0.65 dB peak-to-peak, significantly smaller than on a sunny, warmer day in August (about 1.2 dB peak-to-peak; Figure 3:4) The corresponding daily ambient temperature ranges were 1 \({}^{\circ}\)C and at least 8 \({}^{\circ}\)C, respectively. These differences can be attributed mostly to thermal effects on the LNB. Now, coming back to the cloudy-day case, the relative humidity was also significant, and the ambient temperature was close to the dew point. In any event, it seemed that the average beacon level was slightly lower than in clear-sky days, which should mean that there is a constant additional attenuation due to water vapor and the clouds. A final word is about the fact that we were always carrying out relative measurements of rain attenuation with respect to a daily template. This made our post-processed measurements insensitive to possible drops in the signal level for a few hours or days due to operational reasons. Provided that both ends of the rain event were affected by the same signal level, we relied on the fact that daily templates are capable of removing not only gas, cloud, thermal,and daily antenna mispointing effects, but also a drop in the satellite's transmit power.