scholarly journals Use of ultra-small space vehicles for studying near-Earth plasma by radiophysical methods

2019 ◽  
Vol 18 (1) ◽  
pp. 154-162
Author(s):  
D. V. Chugunin ◽  
A. A. Chernyshov ◽  
M. M. Mogilevsky ◽  
I. L. Moiseenko ◽  
A. A. Petrukovich
Keyword(s):  
Plasma Density ◽  
Phase Difference ◽  
Space Vehicles ◽  
Small Space ◽  
Radio Receivers ◽  
Transmitter Power ◽  
Radio Signals ◽  
Radio Transmitters ◽  
Radio Band ◽  
To Receive

The paper shows the possibility to measure plasma density and its fluctuations in the ionosphere on ultra-small space spacecraft using radiophysical methods that allow determining the characteristics of the medium through which radiation is transmitted. It is assumed that each spacecraft will have a navigational satellite receiver, as well as a device for emitting and detecting a signal at two multiple frequencies in the radio band. With this approach, information on plasma density is contained in the received phase difference. Radio receivers and radio transmitters on satellites constantly exchange radio signals and then it is possible to determine the electron concentration and its fluctuations from the phase shift. The authors obtained numerical estimates of the resulting phase difference for different frequencies from 10 MHz to 10 GHz with typical ionospheric parameters depending on the distance between the satellites. Calculations were also made to determine the maximum distance between satellites at which it is possible to receive a signal, provided that the transmitter power is 2 watts.

scholarly journals Investigation of the technology of mutual navigation and orientation of small space vehicles flying in formation

2019 ◽  
Vol 18 (1) ◽  
pp. 88-93
Author(s):  
A. V. Nebylov ◽  
V. V. Perliouk ◽  
T. S. Leontieva
Keyword(s):  
Video Camera ◽  
Space Vehicles ◽  
Radio Communication ◽  
Small Space ◽  
Modeling Simulation ◽  
Ground Station ◽  
Bench Experiment ◽  
Radio Communication System ◽  
The Cost ◽  
Orbital Constellation

The paper presents the problem of ensuring support of the flight of a group of small spacecraft (microsatellites) taking into account the small mutual distances between them. The purpose of using the orbital constellation specified is to create a radio communication system to control remote objects like unmanned aerial vehicles and ground robots located in hard-to-reach areas of the Earth from the Central ground station. To reduce the cost of microsatellite design, it was decided to rigidly fix the receiving and transmitting antennas on their housings and use the spatial orientation of the entire apparatus for antenna guidance. This seriously complicated the tasks of navigation and orientation of microsatellites in a formation and required the development of a new method for determining the orientation of a single microsatellite. The essence of the method is to process the image obtained by means of a video camera mounted on a nearby microsatellite. We used methods of computer vision. The results of mathematical modeling simulation, as well as the results of full-scale bench experiment confirming the efficiency of the proposed method are presented.

GPS and Cellular Radio Measurement Integration

2000 ◽  
Vol 53 (3) ◽  
pp. 451-463 ◽  
Author(s):  
Ian D. Kitching
Keyword(s):  
Gps Tracking ◽  
Integrated Navigation ◽  
Cellular Radio ◽  
Positional Accuracy ◽  
Integrated Navigation System ◽  
Radio Receivers ◽  
Performance Accuracy ◽  
Assisted Gps ◽  
Radio Signals ◽  
Radio Measurement

In many combined GPS/cellular radio receivers, the cellular radio segment is not used to aid the positioning process. Recently proposed Assisted-GPS systems use the communications channel to improve receiver time-to-first-fix and the GPS tracking sensitivity. However, the cellular radio signals can also be used for locating the receiver. Studies using the GSM mobile communication system have shown positional accuracy comparable to that of SA-degraded GPS. To achieve maximum performance (accuracy, availability, integrity and reliability), both sources of positioning information, GPS and cellular, should be regarded as sensor inputs to an integrated navigation system. In this way the benefits of both systems can be fully exploited to produce an optimal navigation solution.

Formation and development of the Ukrainian network of meteor radio observations

2021 ◽  
Vol 27 (3) ◽  
pp. 85-92
Author(s):  
F.I. Bushuev ◽  
◽  
M.P. Kaliuzhnyi ◽  
N.A. Kulichenko ◽  
A.V. Shulga ◽  
...  
Keyword(s):  
Remote Access ◽  
Frequency Range ◽  
Kinematic Parameters ◽  
Radio Range ◽  
Continuous Registration ◽  
Radio Signals ◽  
Current Monitoring ◽  
To Receive ◽  
E Mail ◽  
Meteor Radio

During the decade of research, the Research Institute “Mykolaiv Astronomical Observatory” (RI “MAO”) developed hardware and software for monitoring, extracting, and calculating the parameters of meteor phenomena using the forward scattering by meteor ionized trail of the signals of over-the-horizon FM-stations broadcasted in the frequency range of 88—108 MHz. This allowed creating a network of observations of meteor phenomena in the radio range, which consists of six stations located in Mykolaiv (three stations), Rivne, Lviv, and Hlukhiv. The stations have identical hardware and software. Yagi-Uda antennas with six or eight horizontal vibrators and SDR receivers based at RTR2832U microchip are used to receive radio signals. The station software performs continuous registration and analysis of received radio signals at the output of quadrature detectors of the receivers, automatic detection of moments of appearances of meteor reflections, formation, and sending by e-mail daily reports on detected meteor phenomena. Equipment setup and current monitoring of stations operations are carried out by the RI «MAO» using remote access to station computers via the Internet. Monthly reports on the number of meteor events recorded by each station are posted on the site of Radio Meteor Observation Bulletin (RMOB). The article presents the results, obtained by the network in 2017—2019, confirming a correspondence of daily variations in the number of meteors registered by network stations, to the known dependence (observation of meteors in the apex and antapex), as well as a correspondence between the expected characteristics (in time and intensity) of three meteor showers (Perseids, Geminids and Quadrantids) and that had been obtained by the network. Recommendations are also given in the article for additional research aimed at achieving the main goal, namely, expanding information about meteor phenomena, including the estimating of kinematic parameters (velocities, radiants) of meteoroids and their relationship with potentially hazardous asteroids.

Detecting Electronic Initiators Using Electromagnetic Emissions

2014 ◽  
pp. 69-99
Author(s):  
Colin Stagner ◽  
Sarah Seguin ◽  
Steve Grant ◽  
Daryl Beetner
Keyword(s):  
Low Power ◽  
Normal Operation ◽  
Radio Receivers ◽  
Novel Technique ◽  
Different Types ◽  
Radio Signals ◽  
Electromagnetic Emissions ◽  
Weak Stimulation ◽  
Explosive Device

The accurate and timely discovery of radio receivers can assist in the detection of radio-controlled explosives. By detecting radio receivers, it is possible to indirectly infer the presence of an explosive device. Radio receivers unintentionally emit low-power radio signals during normal operation. By using a weak stimulation signal, it is possible to inject a known signal into these unintended emissions. This process is known as stimulated emissions. Unlike chemical traces, these stimulated emissions can propagate through walls and air-tight containers. The following case study discusses methods for detecting and locating two different types of radio receivers. Functional stimulated emissions detectors are constructed, and their performance is analyzed. Stimulated emissions are capable of detecting super-regenerative receivers at distances of at least one hundred meters and accurately locating superheterodyne receivers at distances of at least fifty meters. These results demonstrate a novel technique for detecting potential explosive threats at stand-off detection distances.

scholarly journals Atmospheric polarimetric effects on GNSS radio occultations: the ROHP-PAZ field campaign

2016 ◽  
Vol 16 (2) ◽  
pp. 635-649 ◽  
Author(s):  
R. Padullés ◽  
E. Cardellach ◽  
M. de la Torre Juárez ◽  
S. Tomás ◽  
F. J. Turk ◽  
...  
Keyword(s):  
Phase Difference ◽  
Heavy Rain ◽  
Satellite System ◽  
Ground Field ◽  
Field Campaign ◽  
Radio Signals ◽  
Sensitivity Studies ◽  
Rain Events ◽  
Global Navigation Satellite ◽  
Measured Phase

Abstract. This study describes the first experimental observations showing that hydrometeors induce polarimetric signatures in global navigation satellite system (GNSS) signals. This evidence is relevant to the PAZ low Earth orbiter, which will test the concept and applications of polarimetric GNSS radio occultation (RO) (i.e. ROs obtained with a dual-polarization antenna). A ground field campaign was carried out in preparation for PAZ to verify the theoretical sensitivity studies on this concept (Cardellach et al., 2015). The main aim of the campaign is to identify and understand the factors that might affect the polarimetric GNSS observables. Studied for the first time, GNSS signals measured with two polarimetric antennas (H, horizontal, and V, vertical) are shown to discriminate between heavy rain events by comparing the measured phase difference between the H and V phase delays (ΔΦ) in different weather scenarios. The measured phase difference indicates higher dispersion under rain conditions. When individual events are examined, significant increases in ΔΦ occur when the radio signals cross rain cells. Moreover, the amplitude of such a signal is much higher than the theoretical prediction for precipitation; thus, other sources of polarimetric signatures have been explored and identified. Modelling of other hydrometeors, such as melting particles and ice crystals, have been proposed to explain the obtained measurements, with good agreement in more than 90 % of the cases.

Structure function analysis of plasma density fluctuations during total loss of lock of GPS signal events

2020 ◽  
Author(s):  
Hossein Ghadjari ◽  
David Knudsen ◽  
Susan Skone
Keyword(s):  
Structure Function ◽  
Plasma Density ◽  
Large Scale ◽  
Function Analysis ◽  
Density Fluctuations ◽  
Total Loss ◽  
Small Scale ◽  
Self Similarity ◽  
Radio Signals ◽  
Swarm Mission

<p>Ionospheric irregularities are fluctuations or structures of plasma density that affect the propagation of radio signals. Whenever large-scale irregularities break up into meso and small-scale irregularities, these processes become similar to a turbulence cascade. In order to have a better comparison between this and plasma density irregularities, we study different orders of structure functions of plasma density of total loss of lock events measured with the faceplate measurements of plasma density and the GPS measurements from the Swarm mission. Total loss of lock of GPS signal is a physical proxy for severe degradation of GPS signals. In addition to different orders of structure-function, we study the existence of self-similarity or multifractality of plasma density of total loss of lock events to investigate any possible intermittent fluctuations. </p>

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