Remote sensing of ocean roughness using reflected signals from digital communication satellites is demonstrated in an airborne experiment. Transmitted data are approximated as an infinitely long sequence of random bits, which is experimentally a hypothesis confirmed for the S-band XM radio signal. On July 2, 2010, a signal recorder was flown at an altitude of 3.17 km off the coast of Virginia, collecting ocean-reflected signals from both geostationary satellites identified as “Rhythm” and “Blues,” which were broadcasting the XM radio signal. Direct and reflected signals from the same channel were cross-correlated, producing a waveform that agreed well with a model generated at the 7.5-m/s wind speed reported from the Chesapeake Lighthouse. Adjusting this model to fit the experimental data produced an optimal estimate of 6 m/s. A Monte Carlo approach predicted errors of 0.5% from the simulated reflected XM radio signals and 2%-10% from simulated reflected Global Navigation Satellite System (GNSS-R) signals. This improvement was attributed to the higher ( ~ 30 dB) power in the XM radio signal. The availability of communication satellite transmissions, in all frequency bands used for remote sensing, opens the possibility of using signals of opportunity as low-cost alternatives to radiometry or scatterometry.
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机译：机载实验证明了利用来自数字通信卫星的反射信号对海洋粗糙度的遥感。传输的数据近似为无限长的随机比特序列，这在实验上是针对S波段XM无线电信号确认的假设。 2010年7月2日，一台信号记录仪在距离弗吉尼亚州3.17公里的高空飞行，从被标识为“节奏”和“蓝调”的对地静止卫星收集海洋反射的信号，这些卫星正在广播XM无线电信号。来自同一通道的直接和反射信号互相关，产生的波形与切萨皮克灯塔报告的以7.5 m / s风速生成的模型非常吻合。调整此模型以适合实验数据可产生6 m / s的最佳估计。蒙特卡洛方法预测的模拟反射XM无线电信号误差为0.5％，模拟反射全球导航卫星系统（GNSS-R）信号误差为2％-10％。这种改进归因于XM无线电信号中更高的功率（〜30 dB）。在用于遥感的所有频带中通信卫星传输的可用性，开辟了将机会信号用作辐射测定法或散射测定法的低成本替代方案的可能性。
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