机载GNSS-R海面风场反演信号处理方法研究

摘要

在机载GNSS-R海面风场反演应用中,针对反射信号通常采取1 ms的相干积分和1 000次的非相干累加,但相干积分时间的选择并没有经过充分的讨论,尚不明确1 ms是否为最佳的相干积分时间,低海况时1 000次的非相干累加结果在时延功率曲线拖尾处仍存在明显噪声,难以满足观测灵敏度需求.针对这两个问题,通过比较不同相干积分时间处理后的信噪比,并从机载几何关系与散射功率分布的角度分析并论证了最佳相干积分时间为1 ms;针对不同的海况,以时延功率曲线拖尾处最终的信噪比为评判标准,给出了具体的相干-非相干累加方案,仿真结果表明,低海况时的信噪比提升了7～16 dB.%In airborne GNSS-R sea surface wind retrieval,it is a typical way to use 1ms coherent integration and 1 000 noncoherent accumulation,but the choice of coherent time has not been fully researched and it' s not sure if the 1ms is the best choice,the delay waveform result under low wind speed after 1 000 nonchoerent accumulation is still noisy and unsuitable for observation sensitivity.For these two problems,by comparing results of different coherent integration time,it is demonstrated that 1ms is the optimal coherent integration time from the aspect of airborne geometry and distribution of scattering power;for different sea state and taking the SNR of delay waveforms as criterion,the coherent and noncoherent accumulation design is given.Simulation result shows that the SNR under low wind speed is increased by 7～16 dB.