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Subject and Purpose. The paper presents a building concept of a promising meteor-burst communication system with enhanced bandwidth, noise immunity and covert operation of the system. Methods and Methodology. The proposed methods and technical solutions include selection of meteor-burst communication network topologies and employment of code division multiplexing and software-controlled intelligent antennas (SMART antennas) with adaptive techniques in view of varying operating conditions. Results. A meteor-burst communication network has been proposed in several topology variants providing a means of a simultaneous assess of subscriber stations to several base stations of the network, with both subscriber and base stations employing SMART antennas. It has been shown that the software-controlled pointing of these antennas should take into account seasonal changes in the radiant density of the sporadic meteor complex, implying that the radiation pattern maxima should be placed in the most probability areas of the appropriate meteor tracks, with pattern nulls located on the interference source directions. Signals with direct sequence spread spectrum have proved themselves well against interference fading. For these signals, digital processing techniques have been suggested. Conclusion. It has been shown that the proposed concept of enhanced bandwidth, noise immunity and covert operation of the meteor-burst communication system, as well as its subsequent refinement, is expedient to implement through the use of Software Defined Radio, SDR.

Subject and Purpose. The paper presents a technology of constructing a promising meteor-burst communication system (MBCS) with code division multiplexing. It increases the bandwidth and improves the noise immunity and covert operation of the system. Methods and Methodology. The proposed technology is based on software-defined radio (SDR) and provides MBCS adaptation to the environment conditions by means of software parameter control of the signals and their transfer protocols. It includes a technique of forming a large ensemble of signals with a direct sequence spread spectrum and improved auto- and cross-correlation properties, involves the optimal reception and matched digital filtering of large-base signals. In order to improve the noise immunity, the narrow-band interference rejection in the signal spectrum is proposed and is jointly software installed with the matched filtering. The detection and synchronization techniques effectively working in the non-Gaussian and non-stationary interference conditions gained consideration. Results. A method of forming a large ensemble of direct sequence spread spectrum signals with improved auto- and cross-correlation properties has been software implemented using a pseudorandom permutation of codeword elements of a maximum-length register code. Designed with the use of fast Fourier transforms, algorithms of digital matched filtering and interference rejection as applied to large-base signals have been implemented via field-programmable gate arrays (FPGA). A method of detection and synchronization of large-base signals has been proposed and software implemented on the FPGA basis. Conclusion. The proposed algorithms and their implementation methods make it possible to increase the bandwidth, improve noise immunity and enhance covert operation of the meteor-burst communication system with code division multiplexing.

This paper examines the possibility of joint reception of radio reflections from the same meteor trails simultaneously at two spaced receivers. A refined simulation of a joint reception area (JRA) of meteor radio reflections on the basis of a diffraction theory of oblique scattering of radio waves off ionized meteor trails is performed for radio links of moderate (500 km) and medium (1000 km) lengths. The obtained results may be particularly useful for territory planning of meteor burst communication (MBC) networks with the spatial division of subscribers (SDMA technology). The simulated JRAs also characterize an interception probability of messages. This knowledge is especially important in designing highly secure MBC, such as meteor key distribution systems, intended for the creation of two identical copies of a shared secret key at both sides of the meteor radio link.

The aim of this article is to justify the usefulness of meteor communication network usage as a telecommunication basis on the access connectivity network for Vessel traffic management on their way to the Arctic Russian infrastructure in the coastal zone of the northern sea route. It represent us the main options, from the point of view of system analysis, which characterise the telecommunication technologies of meteor connection, structural-functional scheme, generalized mathematical model of the network consisting of the radiotransmitter and receiver including antenna systems. It is represented the usage of adaptive antenna grids as UHF antenna systems.

Space weather's intense variance has a seemingly random effect on radio wave propagation in the Very High Frequency (VHF) portion of the electromagnetic spectrum. In this paper, key models are developed to analyze and estimate performance of wireless systems in weak-signal propagation mediums. Chiefly, meteor burst communication, auroral propagation, and earth-moon-earth communication models are constructed and simulated with MATLAB. The experimental results are confirmed through experimental testing and data comparison. Overall, modeling of these space weather events is used in predicting the effectiveness of radio equipment through these weak-signal modes.

Radio emission from meteors or meteor radio afterglows (MRAs) were first detected using the all-sky imaging capabilities of the first station of the Long Wavelength Array (LWA1). In this work, we use the recently commissioned LWA Sevilleta (LWA-SV) station along with the LWA1 to carry out co-ordinated observations. The combined all-sky observations with LWA1 and LWA-SV have co-observed 32 MRAs and 21 transmitter reflections from meteors (meteor scatter events) which are believed to be specular reflections from overdense trails. The flux density of the events observed by each station were measured from the all-sky images. Triangulating the angular direction of events from each station gave the physical location and the distance of the event to each station. The luminosity of the events in each station were calculated using the flux distance relation for an isotropic source. The luminosity distribution for MRAs and meteor scatter events observed by each station shows a clear distinction between these two types of events as the ratio of luminosities are closer to unity for MRAs than the meteor scatter events. Furthermore, we find that MRAs follow an isotropic radiation pattern. This suggests, either a complete incoherent emission mechanism or an incoherent addition of coherently emitting small regions within the meteor trail., 17 pages, 8 figures

Channel nonreciprocity is one of understudied features of meteor-scatter radio propagation that is caused mainly by polarization phenomena in the channel. For correct estimation of the nonreciprocity level, accurate values of the Faraday polarization twist are required that leads to problem of calculation of Total Electron Content of the ionosphere (TEC) along the signal propagation path. In this paper, the TEC is calculated by direct numerical integration of the ionosphere electron density throughout uplink to a meteor trail. The calculation method is based on division of the uplink path into several segments, each characterized by its own electron density height profile. Our computations made for 10000 various meteor trails simulated for a typical meteor radio link of 720-km length showed quite unambiguously that precise integration along the propagation path can be replaced with high accuracy by simple integration over the single electron height profile containing the signal reflection point. Estimates of the difference between the TEC values calculated for the opposite propagation uplink paths to meteor trail from both link ends are presented. It is shown that these differences are tiny and can be neglected at modeling meteor-scatter links.

The ability to receive electromagnetic waves reflected from meteor traces is the basis for the construction of meteor burst communication (MBC) systems. MBC has a low data rate (about a few dozen kilobits per second). Therefore, from the point of view of increasing the information transfer rate, we can use multi-frequency signals, for example, OFDM signals. These signals occupy a smaller frequency band, but have a high peak-to-average power ratio. In this article, we used simulation modeling to transmit information in an MBC system using multi-frequency signals under the condition of amplitude limitation on the transmitting module., Возможность приема отраженных от метеорных следов электромагнитных колебаний лежит в основе построения систем метеорной связи. Метеорная радиосвязь имеет низкую скорость передачи данных (единицы-десятки бит в секунду). С точки зрения повышения скорости передачи информации мы можем использовать многочастотные сигналы, например, сигналы OFDM. Эти сигналы занимают меньшую полосу частот, но обладают высоким значением пик-фактора. Выполнено имитационное моделирование передачи информации в метеорном канале при использовании многочастотных сигналов при условии амплитудного ограничения на передающем модуле.

When space dust rushes into the atmosphere, oxygen and nitrogen are ionized by frictional heat. Along the dust flight path, a very long cylindrical plasma tube, 10 meters in diameter and several kilometers long is formed. The long plasma tube is called “meteor burst” and is a good reflector for radio waves in the VHF band. Non-line-of-sight communication performed using this reflector is called “meteor burst communication”. In this chapter, the basics of meteor burst communication and its applications are outlined.

A lot of research and experiments on meteor burst communication described in the previous chapter have been done by research institutions, educational institutions, and amateur radio operators. The contents of research and experiments are roughly classified into two categories. One is to investigate the frequency and duration of meteor bursts themselves, and the other is to study data transmission using meteor bursts. This chapter introduces some experiments on meteor burst communications conducted in Japan and the method of QSO by meteor scatter communications conducted by amateur radio operators.

Integrating adaptive modulation and coding techniques into time-varying meteor burst channels with joint data detection and channel estimation at the receiver can greatly increase the average throughput of a meteor burst communication system (MBCS). Although the per-survivor processing algorithm (PSPA) based on joint data and channel estimation provides superior performance and robustness for MBCS, it is very difficult to implement it into practice due to the extremely high computational complexity. An adaptive state reduction scheme using a dimension-down PSPA (ADPSP) with few states in the trellis diagram is proposed based on the slow-fading characteristic of the meteor burst channel. It has the advantages of the dimension-down PSPA (D-PSPA) and the adaptive state reduction scheme based on PSPA proposed in our previous work. The scheme is proposed to reduce the computation complexity and memory size for exponentially decaying meteor burst channels and make the maximum likelihood sequence detection available for adaptive data transmission. Based on the estimation of parameters of the meteor burst channel, the adaptive threshold is obtained in order to decrease the computation compleixty of PSPA, where the states close to the correct one in the trellis is selected. Simulation results are presented to validate the theoretical analysis. It is shown that the proposed adaptive state reduction scheme using a D-PSPA can obtain a good tradeoff between the achievable performance and its dynamically computation complexity, as well as provide reliable data transmission for MBCS using adaptive coding and modulation.

The paper describes a method for simulation of frequency-selectivity of meteor scatter channel that takes into account its nonstationarity, nonreciprocity, and stochastic nature. The amplitude-frequency and phase-frequency responses of the channel obtained by averaging large number of single meteor radio reflections modeled for the typical meteor radio link of Moscow-Kazan of 720-km length are presented. A problem of nonsimultaneous detection of radio signals with large frequency diversity is discussed.

The paper briefly outlines main key points in history of radio meteor research at the Kazan Federal University starting from the first radar observations of meteor radio reflections to development of unique radio systems for high-precision (nanosecond) distant synchronization of time scales. Recent achievements in designing of promising meteor systems for creation and secure distribution of secret encryption keys are considered. Main scientific and applied problems in studying nonreciprocal properties of radio wave propagation in meteor burst communications are discussed.

In this paper, the authors perform the first attempt on examining the possible existence of ionized meteor trails that provide combined forward and backward scattering of radio waves at radio links larger 300 ​km. The aut hors call such meteor trails as “Forward-Backward Scattering” or, simply, FBS-trails and propose a model for their computer simulation. The authors believe that the FBS-trails might find use in a variety of practical applications, including precise time synchronization of passive remote stations. Based on simulation results, it was found that the most reliable distinctive feature of the FBS-trails is their nearly transverse orientation relative to axis of meteor-scatter radio link. The longer the radio link, the less probable FBS-trails become, and almost all detections occur from meteor trails that provide only a single-direction (the forward) scattering. Depending on the link length, the percentage of FBS-trails in total number of detected meteor events varies between 1% (at meteor-scatter links longer 1500 ​km) to about 10% (at meteor-scatter links shorter 150 ​km).

The statistics of gravity wave momentum flux estimation are investigated using data from the MU radar at Shigariki, Japan (136°E, 35°N). The radar has been operating during campaign periods since 1986. The first part of the paper focuses on a multi-day campaign during October 13–31, 1986. The second part of the paper investigates data after 2006 when the radar was operated in a meteor scatter mode. Momentum fluxes are derived from both the turbulent scatter and the meteor scatter measurements, but the techniques are quite different. Probability Distribution Functions are formed using turbulent scatter data. These show that wave packets sometimes have momentum flux magnitudes in excess of 100 m 2 s −2 . The technique for meteor radars, introduced by Hocking (2005), has been widely adopted by the radar community in recent years. The momentum flux estimated using this technique is found to be anti-correlated with the background tidal winds. A validation investigation is carried out for periods with a high meteor echo data rate. The conclusion was that the method can be used to calculate the sign of momentum flux, but does not accurately specify the magnitude.

We present the first global simulations on the occurrence of meteor trail plasma irregularities. These results seek to answer the following questions: when a meteoroid disintegrates in the atmosphere, will the resulting trail become plasma turbulent? What are the factors influencing the development of turbulence? and how do these trails vary on a global scale? Understanding meteor trail plasma turbulence is important because turbulent meteor trails are visible as non-specular trails to coherent radars. Turbulence also influences the evolution of specular radar meteor trails; this fact is important for the inference of mesospheric temperatures from the trail diffusion rates, and their usage for meteor burst communication. We provide evidence of the significant effect that neutral atmospheric winds and ionospheric plasma density have on the variability of meteor trail evolution and on the observation of non-specular meteor trails. We demonstrate that trails are far less likely to become and remain turbulent in daylight, explaining several observational trends for non-specular and specular meteor trails.

We introduce Shooting to the Stars, in short SttS, a secure location verification algorithm leveraging Meteor Burst Communications (MBC)–the ephemeral, ionized stripe generated by meteors. SttS leverages intrinsic peculiarities of MBC, such as robustness to both eavesdropping and jamming, while also enjoying ease of deployment and secure authentication of the transmitting source. SttS enables the verification of the position of a passive receiver by exploiting the radio reflection properties of ephemeral meteor trails, combined with multiple anchors (N) that can be deployed even hundreds of Km from the receiver itself. We developed a complete theoretical model for our solution–rooted on sound literature and past experimental campaigns–, and fully tested it with extensive simulations. Results show that SttS is highly reliable in guaranteeing position verification, and that it can detect a location spoofing attack even when up to $\left({\lceil \frac {N}{2}\rceil -1}\right)$ anchors are compromised by an adversary. Finally, it is completely tunable, trading off accuracy with the number of observed trails–for instance, observing just 200 trails enables to correctly classify the the location as valid or not with a 0.99 probability.

Meteor burst communication is an important communication mode for a number of possible civilian and military applications. This paper proposes a channel modeling and simulation based on OPNET for meteor burst communications. Analyzing the characteristics of underdense meteor burst channel, the multi-layer node models of master station and slave station are presented to create practical simulation scenario of meteor burst communications. The simulation processes of half-duplex communication as well as full-duplex communication are designed to execute simulation. The results demonstrated that the channel model based on OPNET is consisted with meteor burst communication very well, and full-duplex communication is better than full-duplex communication in effectiveness.

Main physical principles of meteor-burst communication were considered. The block diagram of the hardware-software complex for the remote sensing of meteor trails was offered. The complex is based on the principles of software-defined radio. The paper describes the software with the example of received data. This complex allows eliminating a number of disadvantages of meteor-burst communication, increasing the communication distance and enhancing noise immunity based on the choice of optimum working frequencies according to remote sensing data.

In this paper, according to the characteristics of meteor burst communication network, a meteor burst network is designed based on OPNET simulation environment. Then the simulation results of the data amount of the corresponding nodes and the total amount of communication are obtained. Compared with the data of point-to-point node communication, the simulation results show that the simulation network can meet the characteristics of meteoric meteorological communication, and the design of the networking method improves the meteoric traces communication efficiency, which provides a reference for meteoric burst network construction.

The paper reports experimental observations performed with the radar meteor scatter technology using an equipment installed on the Planetarium and Astronomical Observatory of Gorga. Since the relationship between Near Earth Objects and meteor stream, the technique, with a constant monitoring of the sky, may be able to identify unobserved Near Earth Object. Further improvements would also allow the identification of space debris.

The authors consider a possibility of observation of meteor trails providing simultaneous scattering of a probing signal both in forward and backward directions. Such trails might present some valuable data on physics of meteor phenomena useful both for improving of theoretical models and for development of advanced technologies for meteor burst communications. By computer simulation, we identified principal distinctive properties of the 2-way scattering meteor trails and assessed their percentage at different geographical locations of a meteor radio link.