摘要
针对高频射线测高模型未考虑电离层突发E层(sporadic-E,Es层)的问题,从电离层物理结构特性入手,结合实测的电离层垂测数据,在多层准抛物模型的基础上研究了含Es层的电离层模型及其在目标高度测量中的应用.首先,利用反转抛物线特性模拟了含Es的电离层模型,并得到了等离子体频率与高度的关系;然后,利用该模型分析了射线的电离层传输路径与发射仰角/频率的关系以及高频射线微多径特征与目标高度的关系;最后,结合含Es的电离层模型与射线微多径特征,提出了基于分段爬山搜索的快速匹配域测高方法,该方法能大大减少搜索时间.研究结果表明:含Es的电离层模型和提出的测高方法能准确估计出目标高度,并具有较强的实时性.
Ionosperic sporadic-E layer （Es layer） is the irregular structure in ionosphere which often occurs in summer ot China, but the current model of height estimation with high frequency rays does not consider the Es layer, which often makes a large error in the estimation of the target height. In this paper, the parameters of the actual ionosphere are analyzed by using the measured data of the ionospheric vertical measurement station and the information about the variation of the ionosphere in southeastern China which was obtained in recent years. The measured data indicate that the probability of occurrence of Es in China is relatively high, especially in summer. When Es appears in summer, the probability of its cut-off frequency greater than 4.5 MHz reaches up to 83.6%, therefore, it is necessary to study the target height measurement model and algorithm when the ionosphere contains Es. Firstly, on the basis of the quasi-parabolic segments ionosphere model and real ionosphere parameters, the ionosphere model containing the Es layer is established. In this model, Es layer and its connection layer with the E layer are represented by parabola and reverse parabola respectively. Then, the high frequency transmission characteristics of the target micro multipath are analyzed based on Es model. The simulation shows that 4 multipath echoes can be simulated by the characteristics of different slant ranges and Doppler frequencies in the multiple echoes of the target. By matching the simulated 4 multipath echoes with the actual high frequency echo of the target, when the matching degree reaches a maximum value, the estimated height value can be obtained. Finally, based on the micro multipath difference between high frequency rays and the ionospheric model with Es layer, a height estimation method using matched-field processing and hill climbing search algorithm is proposed. This method can greatly reduce the search time for obtaining the real height value. Through theoretical analysis and experimental verification, the relationships between the ionospheric plasma frequency and height, between the transmission path of high frequency rays and the elevation angle/transmitting frequency, and between the micro path characteristics of high frequency rays and the height of target are obtained. Ionospheric model with the Es layer and the new target height measurement method based on the matched-field processing can accurately estimate the height of the target and have a faster calculation speed.
作者
罗欢
肖卉
Luo Huan1）2） Xiao Hui2） 1）(95519 Air Force Army of PLA, Zunyi 563000, China） 2） （Aerospace Early Warning Equipment Department, Air Force Early Warning Academy, Wuhan 430019, China)
出处
《物理学报》
SCIE
EI
CAS
CSCD
北大核心
2018年第7期270-281,共12页
Acta Physica Sinica
基金
国家自然科学基金青年科学基金(批准号：51309232)资助的课题.
关键词
电离层突发E层
多层准拋物模型
高频射线
目标高度估计
sporadic-E layer, quasi-parabolic segments model, high frequency ray, target height estimation
