8.2.4 Realistic receiving antenna Four different antennas are considered: The 0 dBd point in the Recommendation ITU-R F.1336 antenna pattern and vertical − polarization (antenna 1) A 1.25 vertical antenna (commercially available antenna, computed pattern when − λ mounted on the top of the bridge a 200 m long tanker), vertical polarization (antenna 2) A satellite dedicated Turnstile antenna, with right hand circular polarization (RHCP) − (antenna 3) A hemispherical 0 dBi gain antenna, vertical polarization (antenna 4). − Using professional software tools for satellite communications, simulations have been carried out to determine the carrier power level at the receiver input and to determine the Eb/N0 in the following cases: Overhead pass − Side pass − Very low pass. − Results corresponding to each scenario are reported in the following sections. 8.2.4.1 Overhead satellite pass A7-22 Overhead satellite pass, carrier at receiver input A7-23 Overhead satellite pass, at demodulator input Eb/N0 8.2.4.2 Side satellite pass Consider a 16° elevation pass, the signal power and corresponding signal quality measured in are presented in the following figures. Due to the variation of the signal strength at the Eb/N0 receiver over time (due to the change of elevation and distance), the signal may fall below the detection threshold. The use of highly robust waveform (as a combination of modulation, coding and structure) can potentially improve the performance at the expense of reduced throughput. A7-24 Carrier level at receiver input, side satellite pass
8.2.4 Realistic receiving antenna Four different antennas are considered: − The 0 dBd point in the Recommendation ITU-R F.1336 antenna pattern and vertical polarization (antenna 1) − A 1.25 λ vertical antenna (commercially available antenna, computed pattern when mounted on the top of the bridge a 200 m long tanker), vertical polarization (antenna 2) − A satellite dedicated Turnstile antenna, with right hand circular polarization (RHCP) (antenna 3) − A hemispherical 0 dBi gain antenna, vertical polarization (antenna 4). Using professional software tools for satellite communications, simulations have been carried out to determine the carrier power level at the receiver input and to determine the Eb/N0 in the following cases: − Overhead pass − Side pass − Very low pass. Results corresponding to each scenario are reported in the following sections. 8.2.4.1 Overhead satellite pass A7-22 Overhead satellite pass, carrier at receiver input A7-23 Overhead satellite pass, Eb/N0 at demodulator input 8.2.4.2 Side satellite pass Consider a 16° elevation pass, the signal power and corresponding signal quality measured in Eb/N0 are presented in the following figures. Due to the variation of the signal strength at the receiver over time (due to the change of elevation and distance), the signal may fall below the detection threshold. The use of highly robust waveform (as a combination of modulation, coding and structure) can potentially improve the performance at the expense of reduced throughput. A7-24 Carrier level at receiver input, side satellite pass
R-REC-M.2092-0-201510-I!!MSW-E.docx