CAJ | 학술논문

天波超视距雷达(OTHR)利用电离层的反射实现远距离探测。由于受到电离层时变因素的影响，在长相干积累时间条件下，回波谱会发生展宽，严重影响OTHR对舰船等低速目标的检测能力。针对OTHR回波受到电离层相位污染后正负Bragg展宽峰发生交叠的情况，该文提出了一种联合短时MUSIC变换(STMT)和改进相位梯度(PGA)法的校正方法(即ST_IPGA法)。该方法首先利用STMT变换得到相位污染的粗估计，对污染回波进行初步补偿；然后采用自适应滑窗滤波器提取纯净且完整的海杂波标校信号；最后利用改进的PGA法估计出剩余相位污染，对污染回波进行精确校正。理论分析和仿真结果表明该方法对于校正严重电离层相位污染导致的正负Bragg展宽峰发生交叠的情况具有明显的效果。
천파초시거뢰체(OTHR)이용전리층적반사실현원거리탐측。유우수도전리층시변인소적영향，재장상간적루시간조건하，회파보회발생전관，엄중영향OTHR대함선등저속목표적검측능력。침대OTHR회파수도전리층상위오염후정부Bragg전관봉발생교첩적정황，해문제출료일충연합단시MUSIC변환(STMT)화개진상위제도(PGA)법적교정방법(즉ST_IPGA법)。해방법수선이용STMT변환득도상위오염적조고계，대오염회파진행초보보상；연후채용자괄응활창려파기제취순정차완정적해잡파표교신호；최후이용개진적PGA법고계출잉여상위오염，대오염회파진행정학교정。이론분석화방진결과표명해방법대우교정엄중전리층상위오염도치적정부Bragg전관봉발생교첩적정황구유명현적효과。
Skywave Over-The-Horizon Radar (OTHR) can achieve long range detection via the ionosphere reflection. However, time-varying ionosphere and multipath effect will lead to serious clutter spectrum spread in long Coherent Integration Time (CIT). It increases difficulty degree of the detection of slow-speed targets. To deal with contaminated echo in the case of the two spreading Bragg peaks overlapping, an ionospheric contamination correction scheme based on Short Time MUSIC Transform (STMT) and improved Phase Gradient Autofocus (PGA) method is proposed. In the scheme, coarse estimation of ionospheric phase contamination can be obtained and compensated by using STMT transform, then an adaptive sliding window filter is utilized to extract the first order clutter (calibration signal). After that, the remanent ionospheric phase contamination can be estimated and compensated accurately by using improved PGA method. Theoretical analysis and simulation results show that the scheme has a good performance on correcting the situation of two spreading Bragg peaks overlapping.