地空传播特性是机载无线电系统设计的重要依据,电波传播试验数据是建立地空传播预测模型的基础.为了深入研究航空移动业务电波传播特性,利用机载ADS-B (automatic dependent surveillance broadcast)信号开展了地空传播试验,对试验数据进行的分析表明,实测传播损耗与ITU-R P.528-3模型预测损耗及自由空间传播损耗的变化趋势一致;同时,还利用抛物方程方法对不同折射条件下的ADS-B信号传播进行了仿真,仿真的地空传播衰落特征与实测数据有较好的一致性.分析结果表明,利用机载ADS-B信号取得的地空传播试验数据是可靠的,这对今后利用ADS-B信号积累传播数据,改进传播预测模型具有重要意义.%The characteristics of the ground-air propagation is an important basis for the design of airborne radio systems, and the experimental data of ground-air propagation are of fundamental importance for the development and testing of prediction models. In order to study the characteristics of the wave propagation of the air mobile service in depth, the signal of airborne automatic dependent surveillance broadcast (ADS-B) system is used to get the experimental data of the ground-air propagation. The experimental data are analyzed, and the results show that the measured transmission loss data have the similar variation trend with the ones predicted by ITU-R P. 528-3 and the free space propagation model. Meanwhile, we use the parabolic equation method to simulate the propagation of the airborne ADS-B signal in different refractive conditions, and the compared result shows that the measured data and the simulated ones have a great agreement. The result of analysis indicates that the experimental data of ground-air propagation obtained by ADS-B signal is reliable, and are of great significance for the future use of ADS-B signal to accumulate the propagation data and will improve the propagation model.
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