Global Navigation Satellite Systems GLONASS Research Articles

Using the Commercial GNSS RO Spire Data in the Neutral Atmosphere for Climate and Weather Prediction Studies

Recently, the NOAA has included GNSS (Global Navigation Satellite System) Radio Occultation (RO) data as one of the crucial long-term observables for weather and climate applications. To include more GNSS RO data in its numerical weather prediction systems, the NOAA Commercial Weather Data Pilot program (CWDP) started to explore the commercial RO data available on the market. After two rounds of pilot studies, the CWDP decided to award the first Indefinite Delivery Indefinite Quantity (IDIQ) contract to GeoOptics and Spire Incs. in 2020. This study examines the quality of Spire RO data products for weather and climate applications. Spire RO data collected from commercial CubeSats are carefully compared with data from Formosa Satellite Mission 7–Constellation Observing System for Meteorology, Ionosphere, and Climate-2 (COSMIC-2), the fifth-generation European Centre for Medium-Range Weather Forecasts (ECMWF) atmospheric reanalysis (ERA5), and high-quality radiosonde data. The results demonstrate that, despite their generally lower Signal-Noise-Ratio (SNR), Spire RO data show a pattern of lowest penetration height similar to that of COSMIC-2. The Spire and COSMIC-2 penetration heights are between 0.6 and 0.8 km altitude over tropical oceans. Although using different GNSS RO receivers, the precision of Spire STRATOS receivers is of the same quality as those of the COSMIC-2 TriG (Global Positioning System—GPS, GALILEO, and GLObal NAvigation Satellite System—GLONASS) RO Receiver System (TGRS) receivers. Furthermore, the Spire and COSMIC-2 retrieval accuracies are quite comparable. We validate the Spire temperature and water vapor profiles by comparing them with collocated radiosonde observation (RAOB) data. Generally, over the height region between 8 km and 16.5 km, the Spire temperature profiles match those from RS41 RAOB very well, with temperature biases of <0.02 K. Over the height range from 17.8 to 26.4 km, the temperature differences are ~−0.034 K, with RS41 RAOB being warmer. We also estimate the error covariance matrix for Spire, COSMIC-2, and KOMPSAT-5. The results show that the COSMIC-2 estimated error covariance values are slightly more significant than those from Spire over the oceans at the mid-latitudes (45°N–30°N and 30°S–45°S), which may be owing to COSMIC-2 SNR being relatively lower at those latitudinal zones.

The results of navigation spacecrafts observations with asymmetry of the onboard antenna amplitude radiation pattern

The received in the Earth surface layer satellite radio signal power depends on the space navigation vehicle onboard antenna parameters, primarily it depends on the amplitude radiation pattern shape. The spacecraft onboard antenna radiation pattern has a complex shape in order to compensate for radio navigation signal power changes as a result of the removal (or approach) of the navigation satellite from the signal consumer. For this reason, the shape of the radiation pattern must have axial symmetry, i.e. it has to be close to the rotation fi gure. As a result of the global navigation satellite system GLONASS radio navigation signals energy characteristics monitoring, VNIIFTRI evaluated amplitude radiation patterns of the onboard antenna-feeder devices of satellites from the orbital constellation, the amplitude radiation patterns asymmetry of some of them was discovered. The asymmetry of the radiation pattern leads to the radio navigation signal (received by the consumer) power dependence on the device angle of the, i.e. on the position of the onboard radiating antenna system of the relative to the signals consumer. The probable reason for the asymmetry is the gradual aging of the active devices in the antenna system. The article purpose is to pay attention of competent specialists to the existing problem.

Probing ionospheric TEC near South Geomagnetic Pole by use of GNSS observations

Total electron content (TEC) is one of the most important parameters of the Earth’s ionosphere. This parameter determines the degree of ionization and the dispersion properties of the ionosphere. Now the most affordable way to determine ionospheric parameters is the use of radio signals from the global navigation satellite systems GLONASS, GPS, GALILEO and BDS. TEC is now being routinely monitored by global GNSS networks almost everywhere on Earth except geomagnetic poles. The observations of TEC at the Vostok antarctic station were carried out jointly by Saint Petersburg State University and Arctic and Antarctic Research Institute. Observations were started in 2016 and continued to this day with small interruptions. In this work we have processed the GNSS observations with RTKLIB and GeNeSiS software packages. As a result of this processing we have estimated the TEC from code and phase observables. The resulting TEC time series were analysed and compared to the global TEC map. A reasonable accordance with previous results has been reached. However, our results are specific to the South Geomagnetic Pole and reflect ionospheric behaviour near it. It can be seen that TEC changes more abruptly near the Geomagnetic Pole than elsewhere. These results may potentially augment our knowledge about ionosphere structure and evolution near the geomagnetic poles.

OBSERVATIONS OF SPACE DEBRIS IN THE VICINITY OF ORBITS OF GLOBAL NAVIGATION SATELLITE SYSTEMS

The problem of the amount and characteristics of space debris in the vicinity of orbits of Global Navigation Satellite Systems (GNSS) is of significant interest from the viewpoint of safe operation of these systems. Attempts have repeatedly been made to search for space debris fragments in a given region of orbits, but have not led to cataloging such objects. Only in 2018, eight space objects were discovered which were not related to active or inactive spacecraft or their launch elements. Photometrical and trajectory observations with optical telescopes are practically the only source of information about characteristics of such objects. The paper presents a summary of the design features and technical characteristics of the new AZT-33VM telescope. We describe a technique for determining orbital parameters of non-cataloged space debris from optical measurements. We report the results of photometric observations of a space object, detected in the vicinity of orbits of the Global Navigation Satellite System GLONASS.

Наблюдения космического мусора в области орбит глобальных навигационных спутниковых систем

The problem of the amount and characteristics of space debris in the vicinity of orbits of Global Navigation Satellite Systems (GNSS) is of significant interest from the viewpoint of safe operation of these systems. Attempts have repeatedly been made to search for space debris fragments in a given region of orbits, but have not led to cataloging such objects. Only in 2018, eight space objects were discovered which were not related to active or inactive spacecraft or their launch elements. Photometrical and trajectory observations with optical telescopes are practically the only source of information about characteristics of such objects. The paper presents a summary of the design features and technical characteristics of the new AZT-33VM telescope. We describe a technique for determining orbital parameters of non-cataloged space debris from optical measurements. We report the results of photometric observations of a space object, detected in the vicinity of orbits of the Global Navigation Satellite System GLONASS.

УСТАНОВКА ДЛЯ ИЗМЕРЕНИЙ ЗАДЕРЖЕК РАСПРОСТРАНЕНИЯ СИГНАЛОВ В ОПТИЧЕСКИХ ЭЛЕМЕНТАХ

The results of the development of an installation for measuring signal propagation delays in optical elements and optical fibers are presented. Measuring the delays of signal propagation in optical elements and optical fibers required for the development of various instruments, in particular, the development of fiber-optic systems, the synchronization time scales for complexes of metrological support of the global navigation satellite system GLONASS and measuring means of ground-based GLONASS, the development of metrological maintenance of fiber-optic communication systems, the development radiophonic systems (e.g., phased arrays with fiber-optical channels, measuring systems with remote antennas). It is shown that the installation allows to implement phase and pulse methods for measuring signal propagation delays introduced by optical elements, as well as a modified pulse method designed to determine the delays in optical elements with a large signal attenuation, when the accuracy of measurements by other methods is reduced due to the increasing influence of noise measuring equipment. The developed method is based on registration of the pulse shape with the help of analog-to-digital Converter, the approximation was a data taking into account information about the original form of pulses to reduce random error caused by the influence of noise, and subsequent determination of temporal characteristics of pulses using parameters approximating functions. The application of the developed method for various forms of laser pulses is considered, the scheme of the installation implementing these methods is presented, and the results of experimental studies of the installation are presented. It is shown that the modified pulse method allows to reduce the measurement error of signal propagation delays in optical fibers and optical elements by 15–20% or more, depending on the introduced attenuation, and the installation for measuring signal propagation delays can be used to control the characteristics of optical fibers and optical elements of various fiber-optic systems.

Responses to the preparation of strong Kamchatka earth-quakes in the lithosphere–atmosphere–ionosphere system, based on new data from integrated ground and iono-spheric monitoring

The experience of short-term forecasting of Kamchatka earthquakes based on complex well measurements at the Petropavlovsk-Kamchatsky geody-namic polygon (PGP) shows that, as a rule, the preparation of strong Kamchatka earthquakes is fairly reliable in the medium-term time scale (months or years be-fore the earthquake). However the determination of the stage beginning imme-diately preceding an earthquake (weeks or days before the main event) is a very difficult task. At present time, the solution of this problem is largely associated with the involvement in the preparation of forecast conclusions of data from continuous monitoring of the ionosphere, carried out by ground-based means of vertical radiosonding and measurements of total electronic content (TEC) using the global navigation satellite system GLONASS and GPS. This is due to the fact that significant changes in a number of ionospheric parameters occur mainly 1-5 days before the Kamchatka earthquakes. The results of the compar-ison of the data of daily monitoring of the ionosphere, including information on TEC, with the data integrated downhole measurements showed a rather high correlation of occurrence of anomalies in the ionosphere before strong earth-quakes with changes in the complex parameters in borehole measurements. As one example, the report presents the results of ionospheric and borehole monitoring obtained in the time neighborhood of the strong (MW= 7.5) the earth-quake that occurred on March 25, 2020 in the area of the Northern Kurils. The results show a high correlation between changes in the specific electrical resis-tivity of the Geospace in the area of the PGP with variations in the TEC and the formation of a number of other anomalies in the ionosphere a few days be-fore the earthquake. These results indicate that it is possible to determine fairly reliably the beginning of the final stage of preparation for a strong earthquake. Currently, methods based on atmospheric parameters monitoring are used quite successfully for predictive estimates of the epicenter and magnitude of an earth-quake: the method of chemical potential corrections for measurements at an altitude of ∼ 100 m, as well as data from measurements of outgoing long-wave infrared radiation (OLR) at the level of the upper edge of clouds (heights of 10 -15 km).

Application the Single Difference Technique in Aircraft Positioning Using the GLONASS System in the Air Transport

The article presents the possibility of using the Between Satellite Single Difference method (BSSD) in the precise determination of the aircraft position in the Global Navigation Satellite System GLONASS navigation system. The paper presents the mathematical model of the BSSD method, describes the research test and presents the results of conducted examinations. The research test was conducted within the implementation of the GLONASS satellite technique in air navigation. The test research uses the actual GLONASS navigation data registered by the Topcon HiperPro receiver, mounted onboard a Cessna 172 aircraft. Obtained findings of the research work are interesting from the perspective of implementation of the GLONASS satellite technique in aviation. It should be emphasized that standard deviations of the determined position of the Cessna 172, using the BSSD method, do not exceed 2m. The article also determines the accuracy of a position of the Cessna 172 in the GLONASS solution with reference to a solution in the GPS navigation system.

ГЕОДЕЗИЧЕСКИЕ МЕТОДЫ ДЛЯ СОЗДАНИЯ ЕДИНОГО ГЕОИНФОРМАЦИОННОГО ПРОСТРАНСТВА

Modern geodesic support is an integral and essential element of the process of collecting spatial information. The article considers geodesic methods for creating a unique geoinformation space: digitization of cartographic materials, ground survey methods (electronic total stations, 3D laser scanning), remote sensing and methods of the global navigation satellite systems GLONASS and GPS. The article also contains recommended conversion options between the coordinate systems SK-95 and GSK-2011. A comparative analysis of the surveyed geodesic methods for geodata col-lection was carried out. Russian and foreign markets of specialized software for processing geodata are considered, appropriate conclusions are made.

Integration of hardware and software tools for VLSI SoC class design support

Design of radio-electronic equipment is connected with formation of the heterogeneous design environment that contains hard and soft solutions from different company. The heterogeneous design environment generates the set of problems. Most of them does not have unified information solutions, in particular, complexity of operating decisions- making and data transmission of design information. One of the well-known way to solve the problem is the integration and formation of unified information environment. The paper presents the method of integration of heterogeneous hardware and software design support tools of the radio-electronic equipment in the unified information environment. As an example, the stage of system design of the digital goniometric satellite navigation receiver using the Global Navigation Satellite System GLONASS is presented. For information exchange between elements of the information environment the transformer to the uniform data format on the basis of the XML language is used. The implementation of the automated workstation for the GNSS receiver design and testing is also considered.

Application of H-maser with increased power in fountain atomic clocks

The state of the art in time and frequency metrology defines many fields of human activity. At present in Russia a special attention is devoted to development of the global navigation satellite system GLONASS and its functional supplements. According to the federal program “Maintenance, advancement and usage of the system GLONASS in 2012-2020 years” a creation of terrestrial rubidium fountain atomic clock with limit achievable Allan deviation no more than 2∙10 -16 is envisaged in 2016 year. A main problem of the fountain atomic clock is a phase noise of interrogation signal probing the atomic clock transition. In the present work a solution of the problem via application of the hydrogen maser with increased power as a reference in synthesis scheme of the interrogation signal is described. This solution caused by simplicity because it does not require cryogenic microwave oscillators or complicated optical systems application.

AUTONOMOUS POWER SUPPLY FOR EXTREME NORTH OBJECTS

This paper describes the autonomous power supply of the Marine Local Differential Subsystem (LDSS) of global navigation satellite systems GLONASS and GPS on the base of wind turbine (WT), equipped with energy storage system. The paper shows the parameters of LDSS and WT and justifies the necessity and reasonability of reclamation of North Russian regions, building a local energy generating systems for electric supply for distributed consumers. Field testing of vertical axis wind turbines was made in Arctic conditions.

СОЗДАНИЕ ВЫСОКОТОЧНОЙ НАВИГАЦИОННОЙ СИСТЕМЫ В РЕСПУБЛИКЕ АРМЕНИЯ

Medium-Earth orbit satellite systems make it possible to provide services on time coordination and navigation support for a wide range of consumers. At present, there are global navigation satellite systems GLONASS (Russia) and GPS (USA). Users of these systems have an opportunity to determine their location accurately with the given characteristics of their navigation devices. In all developed countries the progress of geodesy and cartography is closely related to the implementation of advanced new technologies in both scientific and industrial areas. The introduction of new technologies and equipment in production is essential for the development of geodesy and cartography, bringing the existing geodetic networks and cartographic materials to modern condition. In the Republic of Armenia there are also plans on introduction of the systems for monitoring and management of vehicles for various purposes, as well as it is proposed to establish and implement an effective satellite navigation system to monitor and control traffic on the basis of advanced satellite technology. The article describes the basic steps to create the network of reference stations, GPS, aerial photography of much of the territory of Armenia, the creation of digital terrain model and the new maps by orthophotoplans. The analysis of the materials were carried out, on the basis of which in the Republic in 2015 a high-precision navigation system will be created. Due to the hard work of surveyors, cartographers and topographers the Republic was brought to European states level.

Three-dimensional dynamic deflections and natural frequencies of a stiff footbridge based on measurements of collocated sensors

SUMMARY A redundant system of collocated geodetic sensors and an accelerometer were used to measure the displacements of a stiff, 40-m-long footbridge excited by essentially vertical synchronized jumps. A main output of the measurements was that excitations produced vertical deflections (of the order of several mm), lateral deflections with an amplitude about half that of the vertical, an effect known for various bridges, and also smaller-scale longitudinal deflections, probably induced by the vertical ones. This combination of deflections in three axes is not an artifact of measuring errors, or of limitations of specific instruments, and do not reflect random effects, for they have been observed in different experiments by different sensors (Global Navigation Satellite System-GNSS, i.e., Global Positioning System-GPS plus the Russian Global Navigation Satellite System-GLONASS), robotic total stations-RTS (or robotic theodolite), and an accelerometer, and were tested through control of the measurement errors from time series reflecting no bridge oscillations. In all cases, sensors provided similar estimates of deflections and of deflection-derived dominant frequencies, which were found equal to those derived from the accelerometer. The proposed instrumentation and methodology seem suitable to control deflections of bridges in cases that visibility of satellites is poor or is disrupted by vehicle circulation. Measurement-based modeling of bridges described might be useful for understanding the structural behavior of bridges under several types of dynamic loads and can contribute to the displacement-based design of structures. Copyright © 2013 John Wiley & Sons, Ltd.

Analytical solar radiation pressure modelling for GLONASS using a pixel array

A new method for calculating analytical solar radiation pressure models for GNSS spacecraft has been developed. The method simulates the flux of light from the Sun using a pixel array. The method can cope with a high level of complexity in the spacecraft structure and models effects due to reflected light. Models have been calculated and tested for the Russhar global navigation satellite system GLONASS IIv spacecraft. Results are presented using numerical integration of the force model and long-arc satellite laser ranging (SLR) analysis. The integrated trajectory differs from a precise orbit calculated using a network of global tracking stations by circa 2 m root mean square over a 160 000-km arc. The observed − computed residuals for the 400-day SLR arc are circa 28 mm.

Urban Canyon Vehicle Navigation with Integrated GPS/GLONASS/DR Systems

To date, a number of navigation systems using GPS and other complementary sensors have been developed to offer high-position accuracy and thus increase productivity and efficiency for vehicles and fleet networks. However, these systems are still challenged by the environment of built-up city canyons in terms of delivery of continuous positioning information. Augmentation of current systems with the Global Navigation Satellite System GLONASS offers a solution for increased availability and continuity for urban vehicle navigation. This paper describes the first integrated GPS - GLONASS - dead reckoning DR vehicle navigation system, developed in Australia, and discusses the capabilities of the system operating in urban canyon environments. Results from the city center of Perth, Western Australia, are presented to illustrate improvements in positioning over existing systems from use of the integrated GPS - GLONASS - DR system.