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针对欠密度流星余迹干扰影响天波超视距雷达目标检测的问题,提出了基于总体最小二乘旋转不变估计信号参数(Total Least Squares-Estimating Signal Parameter via Rotational Invariance Techniques TLS-ESPRIT)的欠密度流星余迹干扰抑制算法.首先应用复数据经验模式分解估算流星余迹干扰的位置,并将该位置的回波数据组成Hankel矩阵,然后采用TLS-ESPRIT方法求解Hankel矩阵,解得流星余迹干扰的时域回波,最后从回波数据中去除流星余迹干扰的时域回波,得到流星余迹干扰抑制后的回波数据.与现有流星余迹抑制算法相比,该方法减少了流星余迹干扰的残余和提高了目标的信杂比(SCNR). 相似文献
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天波超视距雷达(OTHR)电波通过电离层折射作下视探测,具有观察距离远,观察范围广的特点.但由于采用HF频段,且电波传播环境复杂,不仅海(地)杂波强,而且有很强的干扰,如电台干扰、工业干扰、冲击噪声、闪电冲击和流星余迹回波等.干扰分长时间干扰和瞬态干扰,瞬态干扰持续时间短、强度大.本文首先讨论OTHR接收到的瞬态干扰的特点;然后讨论了瞬态干扰的滤除方法,即采用特征分解方法滤除海杂波,或在频域直接滤除地杂波,检测出瞬态干扰的位置后,在原始信号中挖除存在瞬态干扰的回波点,并用预测内插的方法,消除瞬态干扰谱对目标掩盖作用,使目标特别是舰船目标能被检测出来;最后通过实测数据的检验. 相似文献
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流星余迹数据通信发展探讨 总被引:2,自引:0,他引:2
本文首先简述了流星余迹通信在数据通信中的作用与地位,然后论述了国外流星余迹通信发展现状与趋势以及我国流星余迹通信发展情况,最后提出了发展我国流星余迹数据通信的几点建议。 相似文献
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本文介绍了流星余迹的基本概念和流星余迹通信的工作原理,介绍了如何估算流星余迹通信的最远距离,提出了流星余迹通信系统的几种网络结构及主要设备的组成。 相似文献
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一、引言流星余迹通信是最近十多年来才发展起来的一种新的通信技术,它是利用流星所形成的电离余迹散射无线电波来进行通信的.由于流星电离余迹存在的时间是有限的,因此要想有效地利用流星余迹进行通信,就必须迸发式地工作.当流星出现而信号较大时就加以利用,而当没有合适的流星出现时,就把通信体系关闭.在这种工作方式中,只要使用比连续工作通信方式所需功率小得多的发射机,就能够进行有效的通信. 相似文献
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An examination is made of the ground illumination footprint of meteor trails and its effect on the simultaneous reception of meteor scatter transmissions by multiple receivers. A technique for calculating the ground illumination footprint of individual trails which provides added insight into the physical mechanisms is presented. The probability of adjacent station reception as a function of location on the ground is calculated by computing the ground illumination footprint of individual trails at different locations and orientations within the common volume and weighting each footprint by the number of trails at that location and orientation. Two different models for the spatial arrival pattern of meteor trails are considered: the first model assumes that trails arrive uniformly over the common volume, and the second calculates the number of arrivals from the spatial distribution of meteor orbits, antenna patterns, time of day, and season. The effect of antenna patterns on the ground illumination footprint of meteor scatter communication is examined 相似文献
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Radio propagation by reflection from meteor trails 总被引:1,自引:0,他引:1
This paper is a survey of those characteristics of meteors, and of meteor propagation, which are important to the understanding and use of meteor ionization insofar as it provides a means of radio transmission. The subjects discussed include the utility of meteor bursts for intermittent radio communication, physical properties of meteors and meteor trails, reflection properties of individual trails, short-term statistical characteristics of received signals, and long-term statistical characteristics of received signals. 相似文献
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Weitzen J.A. Kilpatrick J.A. Mui S.Y. 《Vehicular Technology, IEEE Transactions on》1992,41(4):455-460
A model is developed for predicting the inherent spatial multiplexing or diversity in a widely dispersed network of meteor scatter receivers. The primary measure, network diversity, is defined as the ratio of the arrival rate of useful trails observed by the entire network to the arrival rate at an average node and is less than the number of receivers in the network. Network diversity is calculated from the ground illumination footprint of individual meteor trails and weighted by the spatial arrival pattern of trails. Predictions using the model are compared to an experiment conducted in the western US. Ramifications on the design of meteor scatter communication systems for very large network applications such as automatic vehicle location and tracking are discussed 相似文献
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Meteor scatter: an overview 总被引:3,自引:0,他引:3
The phenomenon of radio propagation using meteor trails is reviewed. Underdense and overdense propagation mechanisms are described. The multipath and fading profile of the meteor channel is examined. Mechanisms other than meteor trails that are commonly observed on meteor links and can change the characteristics of the meteor communication channel are considered. These include sporadic-E propagation, auroral scatter, ionospheric scatter, diffraction, line-of-sight propagation, and tropospheric scatter 相似文献
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V. D. Kukush A. N. Oleynikov S. A. Makovetskyi 《Radioelectronics and Communications Systems》2011,54(5):260-267
Peculiarities of using the TV broadcast signals for radar Doppler measurements of the drift velocity of meteor trails have
been considered. Afunctional block diagram of the measuring apparatus for estimating the Doppler variations of the carrier
frequency of TV broadcast signals reflected from drifting meteor trails was proposed. The developed apparatus made it possible
for the first time to obtain the experimental proof of the possible use of TV broadcast signals for Doppler radiolocation
of meteor trails and investigation of wind-induced motions at heights of the mesopause—lower thermosphere (80–105 km). It
was shown that the variations of hourly average values of carrier frequencies of TV broadcast signals reflected from the meteor
trails featured the intrinsic relationships typical for Doppler radar observations over the meteor trails drifting under the
impact of wind-induced motions at heights 80–105 km. 相似文献
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The use of error correction coding for meteor burst communications is discussed. The cutoff rate is derived for a meteor burst channel model which assumes that the received signal amplitude decays exponentially. The message error rate of a coded system, obtained by means of computer simulation, is compared to that of an uncoded system. A tight upper bound on the performance of the coded system is presented. It is shown that coding can reduce the signal-to-noise ratio (SNR) required for reliable communications via meteor bursts by many decibels. The coding gain is larger at shorter communication ranges where meteor trails, decay faster. It is also shown that the additional improvement achieved by providing the decoder with side information on the instantaneous level of the received signal is small 相似文献
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Measurements over an 850 km path show that radio waves reflected by ionised meteor trails are typically received with the same polarisation as they were transmitted. Furthermore, a vertically polarised wave seems to suffer a 3?4 dB larger loss than a horizontally polarised one. 相似文献
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The performance of meteor burst communication at different ranges for a number of antenna configurations is analyzed. Characteristics of ideal antenna patterns for short- and long-range meteor scatter communication are described. An ideal antenna configuration matches its illumination pattern to the spatial arrival pattern of meteor trails. The analysis is used to compare the performance of several commonly used antenna configurations. It will be demonstrated that the characteristics of antennas which perform well at short ranges are different than those that perform well at long ranges 相似文献
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三维极化滤波及其参数估计 总被引:3,自引:1,他引:2
以高频地波雷达为背景,提出了三维极化向量滤波方法,此法能够滤除二维极化滤波不以滤除的干扰,综合提高极化域和空域的抗干扰能力。文中详细讨论了三维极化滤波参数的估计方法,并给出了扰极化度化度较高时参数的简化估计式。 相似文献
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Fabrizio G. A. Gray D. A. Turley M. D. 《Multidimensional Systems and Signal Processing》2003,14(1-3):241-263
This paper experimentally evaluates the interference cancellation performance of different adaptive beamforming schemes applicable to high frequency (HF) over-the-horizon (OTH) radar systems. Such systems are known to receive multipath and diffusely scattered radio frequency interference produced as a result of reflection from the stratified, dynamic and spatially inhomogeneous ionospheric propagation medium. Apart from quantifying the effectiveness of operational adaptive beamformers in the HF (3–30 MHz) environment, realistic interference models are described and experimentally evaluated in terms of their ability to predict the observed interference cancellation performance which is not well represented by traditional models. Adaptive beamforming algorithms with robustness against jammer motion are also described and their effectiveness is experimentally demonstrated using interference data collected by 32 narrowband receivers of the very wide aperture (2.8 km) Jindalee OTH radar uniform linear array located near Alice Springs in central Australia. 相似文献