射频光传输雷达接收链路的系统优化

System optimization for radio-over-fiber radar receiving link

  • 摘要: 在雷达指标体系中,探测距离和目标分辨能力是其中的重要参数。而噪声系数(NF)和接收链路的压缩动态范围(CDR)则影响着这两个指标。随着射频光传输(ROF)在雷达接收链路中应用的推进,除了对光链路本身的探讨外,还需扩展到接收链路中微波和光波的协同分析。因此,将其中的微波前级放大、射频光传输(ROF)、微波后级放大进行耦合,普适性地探讨接收链路CDR和NF。例如,当光链路噪声功率谱密度为−164 dBm/Hz,光链路增益−20 dB时,可设计前级放大41 dB。在这种情况下,接收链路CDR1dB达143 dB·Hz,噪声系数为4.15 dB,能够同时满足探测距离和目标分辨的要求。对外调制光链路而言,调制器的半波电压可选择在2.0~5.8 V之间,实现性能和成本的平衡。分析从系统角度出发,探讨了基于ROF的接收链路,能够满足雷达功能要求,同时,也为接收链路中电器件和光器件的设计提供了依据。

     

    Abstract: Among parameter system of radar, detection distance and target distinguishable ability are important ones, which are related to compression dynamic range(CDR) and noise figure(NF) of receiving link. Nowadays, applications of radio-over-fiber(ROF) in radar receiving link are moved forward. Besides studying on optical link itself, cooperation analysis on both microwave and optical wave should be given. Therefore, microwave pre-amplifier, ROF link and microwave post-amplifier were coupled together. CDR and NF of receiving link based on ROF were discussed universally. For example, if power spectrum density(PSD) noise of ROF was −164 dBm/Hz and optical gain was −20 dB, the CDR1dB and NF of receiving link could be 143 dB·Hz and 4.15 dB with pre-amplifier of 41 dB. In this case, detection distance and target distinguishable ability could both match requirements of system. Moreover, parameters of optical devices were also discussed. For ROF based on external modulated optical links, half wave voltage of modulators could be among 2.0 to 5.8 V to balance performances and costs. Therefore, studies from the aspects of system proof that receiving link based on ROF could meet the requirements of radar functions. Design principles for electronical and optical devices were provided in the meantime.

     

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