# Indoor Signal Strength Evaluation of the Orbcomm Low Earth Orbit Satellite Constellation +
## 5 Discussion  
In this study, we found that the Orbcomm satellite signals propagated into all rooms of a suburban home. We compared and quantified signal strength in various environments, the results of which are summarized in Figure 4, illustrating the differences between the environments.  
When examining the results from the outdoor measurements, a clear correlation between elevation angle and signal strength is present, which is to be expected. This can be observed in Figure 3. Despite the less-than-ideal conditions in the suburban environment, the signal was still received remarkably strong. The indoor signal strength is notably weaker. In the attic, the strongest signals were received out of all indoor environments. When comparing the 40\({}^{\circ}\) maximum elevation angle range of the attic to the outdoor measurements, the peak adjacent values are 13 dB-Hz lower. Similarly, the median is 13.6 dB-Hz lower. When analyzing the median of the other rooms, it can be observed that the first floor is 15.8 dB-Hz below the outdoor median and the ground floor 14.9 dB-Hz below the outdoor median. Finally, the median \(C/N_{0}\) of the basement is 15.7 dB-Hz below the outdoor median. Remarkable is that the median \(C/N_{0}\) of the ground floor at low elevation angles is higher than the one of the first floor, which might be due to the large windows. Another aspect to consider in indoor environments is that a higher elevation angle does not necessarily imply a higher signal strength, as is illustrated in Figure 4. In an indoor environment, material attenuation also plays a significant role in link performance. The attenuation is influenced by the elevation angle but also the azimuth angle of the satellite.  
When comparing our work to the one conducted by [PERSON] et al., some similarities and differences can be identified. [PERSON] et al. also conducted real-life measurements of the \(C/N_{0}\). However, these measurements were of Iridium satellites inside an office building. The \(C/N_{0}\) results varied between 45 and 60 dB-Hz on the higher floor levels and between 45 and 55 dB-Hz on the lower floor levels [6]. It is important to note a significant distinction between the study by [PERSON] et al. and the present study. Specifically, this work utilizes the Orbcomm satellite constellation, which operates in the VHF frequency range and has an EIRP of 12 dBW [20]. This differs from the Iridium constellation used by [PERSON] et al., which utilizes a bursty L-Band downlink with an EIRP between 10.7 dBW and 27.1 dBW [4]. Therefore, some differences in results are to be expected. Nonetheless, this study indicates that the Orbcomm constellation results in similar \(C/N_{0}\) values in the attic and on the ground floor as the Iridium constellation on the lower floors of an office building.  
Furthermore, when comparing our \(C/N_{0}\) results to those of GNSS, a distinctly higher \(C/N_{0}\) can be observed from the Orbcomm constellation. The \(C/N_{0}\) of GPS in an outdoor environment is approximately 45 dB-Hz [7], whereas the Orbcomm satellites reach a peak \(C/N_{0}\) of approximately 70 dB-Hz in an outdoor environment. Furthermore, the Orbcomm LEO satellite signals exhibit high \(C/N_{0}\) indoors even in comparison to outdoor GPS signals, reaching higher values as GPS in every location. However, it should be noted that in this study, we were unable to detect signals with a CNR below 0 dB. Thus, the lowest value we were able to detect was 43.97 dB-Hz.