On Similarity Transformation and Geodetic Network Distortions Based on Doppler Satellite Observations

Models used in geodesy to transform two sets of coordinates are studied and distortions in geodetic networks are investigated. Commonly used transformation models are first reviewed and most of them are interpreted. Differences between various models are discussed. Pitfalls in partial solutions are then considered. It is shown that only as many chords and/or directional elements can be used in the computation as are needed to completely determine the size or shape of the polyhedron implied in the set of Cartesian coordinates. Each additional element causes the normal matrix to be singular provided that all correlations between the chords are used. A number of tables and maps indicating distortions in the NAD 27, Precise Traverse M-R '72, AUS, and SAD 69 geodetic datums are also included. The residuals of the coordinates are scanned for systematic patterns after transforming each geodetic system to the NWL9D Doppler system. Also, an attempt is made to show scale distortions in the NAD 27

PROGRAMA CIENTÍFICO PARA O MONITORAMENTO EM TEMPO REAL OU PÓS-PROCESSADO DAS IRREGULARIDADES IONOSFÉRICAS E CINTILAÇÃO DOS SINAIS GNSS

O Brasil é um dos países que mais sofrem os efeitos provocados pela ionosfera, principalmente os oriundos da Anomalia de Ionização Equatorial, irregularidades ionosféricas e cintilação dos sinais GNSS (Global Navigation Satellite System). Várias estratégias podem ser utilizadas para minimizar os efeitos, tais como: modelos ionosféricos, arquivos IONEX ou a combinação linear ion-free. Em se tratando do monitoramento da ionosfera a situação é diferente. A quantidade de instrumentos dedicados ao estudo da camada ionosférica é reduzida no âmbito brasileiro. Neste contexto foi desenvolvido o programa científico denominado Ion_Index, com objetivo de estimar indicadores dos níveis de irregularidades da ionosfera e de cintilação dos sinais GNSS em tempo real ou pós-processado, utilizando a infraestrutura já existente de dados GNSS de redes ativas públicas, como a RBMC, a GNSS-SP e a CALIBRA, transformando assim estações GNSS em estações monitoras da camada ionosférica. Dessa forma é proporcionado um aumento na resolução espacial das informações sobre o comportamento da ionosfera na região brasileira, permitindo um melhor entendimento e contribuindo para o desenvolvimento ou aprimoramento de modelos de mitigação. Experimentos utilizando dados de ionossondas digitais e de receptores PolaRxS-PRO da Septentrio (fontes externas) comprovam a eficiência do program

St. Croix region crustal strain study

Maine Geological Survey Open-File 85-76. Resurvey of triangulation stations in St. Croix area.https://digitalmaine.com/mgs_publications/1174/thumbnail.jp

St. Croix region crustal strain study

Maine Geological Survey Open-File 85-76. Resurvey of triangulation stations in St. Croix area.https://digitalmaine.com/mgs_publications/1174/thumbnail.jp

GPS Satellite Surveying

Employ the latest satellite positioning tech with this extensive guide. GPS Satellite Surveying is the classic text on the subject, providing the most comprehensive coverage of global navigation satellite systems applications for surveying. Fullyupdated and expanded to reflect the field\u27s latest developments,this new edition contains new information on GNSS antennas, PrecisePoint Positioning, Real-time Relative Positioning, LatticeReduction, and much more. New contributors offer additional insight that greatly expands the book\u27s reach, providing readers with complete, in-depth coverage of geodetic surveying using satellite technologies. The newest, most cutting-edge tools, technologies,and applications are explored in-depth to help readers stay up to date on best practices and preferred methods, giving them the understanding they need to consistently produce more reliable measurement. Global navigation satellite systems have an array of uses in military, civilian, and commercial applications. In surveying, GNSS receivers are used to position survey markers, buildings, and road construction as accurately as possible with less room for human error. GPS Satellite Surveying provides complete guidancetoward the practical aspects of the field, helping readers to: * Get up to speed on the latest GPS/GNSS developments * Understand how satellite technology is applied tosurveying * Examine in-depth information on adjustments and geodesy * Learn the fundamentals of positioning, lattice adjustment,antennas, and morehttps://digitalcommons.library.umaine.edu/fac_monographs/1240/thumbnail.jp