Comparison of frequency-selective properties of meteor burst channel at the beginning and at the end of radio reflections from meteor trails

© 2017 IEEE. Meteor burst propagation is based on scattering of radio waves from the ionized trails left by fast meteor particles. One of the promising applications of meteor radio propagation is development of Meteor Synchronization Systems (MSSs) for synchronizing two remote stations with potentially subnanosecond accuracy. Frequency-selective properties of meteor burst channel limit potential accuracy of coherent multi-carrier MSS systems. To adapt to frequency distortions of timing signals, a frequency response of the channel should be appropriately considered. Continuous expansion of the meteor trail plasma due to ambipolar diffusion provokes significant changes in frequency-selective properties of the channel at the end of detection of radio reflections. This should be taken into account to assess a minimum channel bandwidth correctly. On the basis of rigorous solution to the problem of diffraction of radio waves on a meteor trail, we perform a numerical simulation of the amplitude-frequency and phase-frequency responses of meteor burst channel. A comparison of the frequency-selective properties of the channel at the beginning and at the end of the signal detection is presented for the cases of radio reflections from underdense and overdense meteor trails. The frequency responses obtained with the diffraction approach are compared with the results of the classical (approximate) theory of a radio reflection from meteor trail

On possibility of using of measurements of random polarization of radio reflections from meteor trails for generating shared encryption keys

© 2017 IEEE. Meteor burst channel is formed by a scattering of radio waves from the ionized trails left by fast meteor particles. Meteor phenomena make the channel to be stochastic. Using this randomness along with approximate reciprocity of radio propagation, two communication points are able to generate a purely random shared encryption key by joint observation on the channel parameters. In previous studies, it was shown that the randomness of carrier phase and propagation time of detected meteor radio reflections can be used for the key generation purposes. However, a polarization of the radio reflections is also random, and it might be used to generate the keys too. In this study, the first ever attempt on examining a possibility of generating of purely random encryption keys using the samples of random polarization of meteor radio reflections is made. By computer simulation based on a rigorous solution to the problem of oblique diffraction of radio waves on meteor trails, statistical properties of the polarization of meteor radio reflections are studied. The estimates of the cross-correlation between the values of polarization measured synchronously at both sides of a radio link and differing due to non-perfect reciprocity of meteor burst channel are presented. Some preliminary results on the testing generation of a random key are also presented in the end of the paper

On the dynamics of nonreciprocal properties of radio reflections from ionized meteor trails

© 2017 IEEE. Meteor burst propagation is based on scattering of radio waves of the meter range from the ionized trails left by fast meteor particles burning at the altitudes of 80-110 km. An interaction between radio wave and the meteor trail is a complex non-stationary process, which is determined by the polarization phenomena at the transmission, propagation, diffraction on the trail, and reception of the wave. These phenomena lead to non-Absolute reciprocity of the radio link both on amplitude and carrier phase. Scattering properties of the meteor trail and associated level of channel nonreciprocity have strong time dependence due to active expansion of the trail. The knowledge of such dependence would be crucial in predicting the moment of minimum channel nonreciprocity. This is particularly important for the implementation of meteor synchronization systems of nanosecond precision and meteor key distribution systems as all these systems rely on reciprocal properties of the channel. Based on a rigorous solution to the problem of oblique diffraction of radio wave on meteor trail, we simulate typical profiles of the dynamics of amplitude and phase nonreciprocity during a single meteor radio reflection. The results on correlation between the dynamics of amplitude nonreciprocity and dynamics of phase nonreciprocity of meteor burst channel are also presented

Analysis and Simulation of Channel Nonreciprocity in Meteor-Burst Communications

© 1963-2012 IEEE.This paper addresses the problem of nonreciprocity of propagation conditions in meteor-burst communication systems (MBCSs). In prior publications, this problem has not gained appropriate attention. The channel nonreciprocity may have a significant impact on such advanced communication systems as meteor synchronization systems with nanosecond precision and meteor key distribution systems intended to securely create two identical copies of a shared secret key at both channel sides. These systems are based on the processing of phase characteristics of meteor radio reflections that need to be accurately modeled. We propose a new MBCS simulation model that is based on a rigorous solution to the problem of oblique diffraction of radio waves on ionized meteor trails. Our diffraction approach allows more accurate simulation of the amplitude and phase characteristics of oppositely propagating signals that makes possible detailed investigation of the channel nonreciprocity effects. Using this approach, we present some preliminary simulation results on the channel nonreciprocity at meteor-burst propagation that prove satisfactory immunity of MBCS to ionospheric disturbances even while operating in severe conditions of polar regions

Abstracts on Radio Direction Finding (1899 - 1995)

The files on this record represent the various databases that originally composed the CD-ROM issue of "Abstracts on Radio Direction Finding" database, which is now part of the Dudley Knox Library's Abstracts and Selected Full Text Documents on Radio Direction Finding (1899 - 1995) Collection. (See Calhoun record https://calhoun.nps.edu/handle/10945/57364 for further information on this collection and the bibliography). Due to issues of technological obsolescence preventing current and future audiences from accessing the bibliography, DKL exported and converted into the three files on this record the various databases contained in the CD-ROM. The contents of these files are: 1) RDFA_CompleteBibliography_xls.zip [RDFA_CompleteBibliography.xls: Metadata for the complete bibliography, in Excel 97-2003 Workbook format; RDFA_Glossary.xls: Glossary of terms, in Excel 97-2003 Workbookformat; RDFA_Biographies.xls: Biographies of leading figures, in Excel 97-2003 Workbook format]; 2) RDFA_CompleteBibliography_csv.zip [RDFA_CompleteBibliography.TXT: Metadata for the complete bibliography, in CSV format; RDFA_Glossary.TXT: Glossary of terms, in CSV format; RDFA_Biographies.TXT: Biographies of leading figures, in CSV format]; 3) RDFA_CompleteBibliography.pdf: A human readable display of the bibliographic data, as a means of double-checking any possible deviations due to conversion

1992 NASA/ASEE Summer Faculty Fellowship Program

For the 28th consecutive year, a NASA/ASEE Summer Faculty Fellowship Program was conducted at the Marshall Space Flight Center (MSFC). The program was conducted by the University of Alabama and MSFC during the period June 1, 1992 through August 7, 1992. Operated under the auspices of the American Society for Engineering Education, the MSFC program, was well as those at other centers, was sponsored by the Office of Educational Affairs, NASA Headquarters, Washington, DC. The basic objectives of the programs, which are the 29th year of operation nationally, are (1) to further the professional knowledge of qualified engineering and science faculty members; (2) to stimulate and exchange ideas between participants and NASA; (3) to enrich and refresh the research and teaching activities of the participants' institutions; and (4) to contribute to the research objectives of the NASA centers

NASA compendium of satellite communications programs

A comprehensive review of worldwide satellite communication programs is reported that ranges in time from the inception of satellite communications to mid-1971. Particular emphasis is placed on program results, including experiments conducted, communications system operational performance, and technology employed

To See the Unseen: A History of Planetary Radar Astronomy

This book relates the history of planetary radar astronomy from its origins in radar to the present day and secondarily to bring to light that history as a case of 'Big Equipment but not Big Science'. Chapter One sketches the emergence of radar astronomy as an ongoing scientific activity at Jodrell Bank, where radar research revealed that meteors were part of the solar system. The chief Big Science driving early radar astronomy experiments was ionospheric research. Chapter Two links the Cold War and the Space Race to the first radar experiments attempted on planetary targets, while recounting the initial achievements of planetary radar, namely, the refinement of the astronomical unit and the rotational rate and direction of Venus. Chapter Three discusses early attempts to organize radar astronomy and the efforts at MIT's Lincoln Laboratory, in conjunction with Harvard radio astronomers, to acquire antenna time unfettered by military priorities. Here, the chief Big Science influencing the development of planetary radar astronomy was radio astronomy. Chapter Four spotlights the evolution of planetary radar astronomy at the Jet Propulsion Laboratory, a NASA facility, at Cornell University's Arecibo Observatory, and at Jodrell Bank. A congeries of funding from the military, the National Science Foundation, and finally NASA marked that evolution, which culminated in planetary radar astronomy finding a single Big Science patron, NASA. Chapter Five analyzes planetary radar astronomy as a science using the theoretical framework provided by philosopher of science Thomas Kuhn. Chapter Six explores the shift in planetary radar astronomy beginning in the 1970s that resulted from its financial and institutional relationship with NASA Big Science. Chapter Seven addresses the Magellan mission and its relation to the evolution of planetary radar astronomy from a ground-based to a space-based activity. Chapters Eight and Nine discuss the research carried out at ground-based facilities by this transformed planetary radar astronomy, as well as the upgrading of the Arecibo and Goldstone radars. A technical essay appended to this book provides an overview of planetary radar techniques, especially range-Doppler mapping

NASA Compendium of Satellite Communications Programs

A comprehensive review is presented of worldwide communication programs that range in time from the inception of satellite communications to August 1971. The programs included are: Echo, Courier, West Ford, Telstar, Relay, Syncom, Lincoln experimental satellites, Intelsat, Tacsat, Skynet, Nato system, and Telesat