Dependence of ground station acquisition effectiveness on geographic location and satellite orbit

1965 ◽  
Vol 2 (3) ◽  
pp. 410-415
Author(s):  
ROBERT L. PYLE ◽  
S. FRED SINGER
Keyword(s):  
Geographic Location ◽  
Satellite Orbit ◽  
Ground Station

scholarly journals The Impact on Geographic Location Accuracy due to Different Satellite Orbit Ephemerides

2009 ◽  
Vol 2009 ◽  
pp. 1-9
Author(s):  
Claudia C. Celestino ◽  
Cristina T. Sousa ◽  
Wilson Yamaguti ◽  
Helio Koiti Kuga
Keyword(s):  
Data Collection ◽  
Geographic Location ◽  
Satellite Orbit ◽  
Environmental Data ◽  
Location Accuracy ◽  
Doppler Shifts ◽  
Precise Ephemeris ◽  
Doppler Data ◽  
Important Input ◽  
The Impact

The current Brazilian System of Environmental Data Collection is composed of several satellites (SCD-1 and 2, CBERS-2 and 2B), Data Collection Platforms (DCPs) spread mostly over the Brazilian territory, and ground reception stations located in Cuiabá and Alcântara. An essential functionality offered to the users is the geographic location of these DCPs. The location is computed by the in-house developed “GEOLOC” program which processes the onboard measured Doppler shifts suffered by the signal transmitted by the DCPs. These data are relayed and stored on ground when the satellite passes over the receiving stations. Another important input data to GEOLOC are the orbit ephemeris of the satellite corresponding to the Doppler data. In this work, the impact on the geographic location accuracy when using orbit ephemeris which can be obtained through several sources is assessed. First, this evaluation is performed by computer simulation of the Doppler data, corresponding to real existing satellite passes. Then real Doppler data are used to assess the performance of the location system. The results indicate that the use of precise ephemeris can improve the performance of GEOLOC by reducing the location errors, and such conclusion can then be extended to similar location systems.

scholarly journals BeiDou Satellites Assistant Determination by Receiving Other GNSS Downlink Signals

2016 ◽  
Vol 2016 ◽  
pp. 1-10
Author(s):  
Lei Chen ◽  
Ke Zhang ◽  
Xiangwei Zhu ◽  
Yangbo Huang ◽  
Gang Ou ◽  
...  
Keyword(s):  
Doppler Frequency ◽  
Satellite Orbit ◽  
Cost Effective ◽  
Satellite System ◽  
Earth Orbit ◽  
Navigation Satellite ◽  
Ground Station ◽  
Minimum Number ◽  
Beidou Satellites ◽  
Global Navigation Satellite

GNSS’s orbit determinations always rely on ground station or intersatellite links (ISL). In the emergency of satellite-to-ground links and ISL break-off, BeiDou navigation satellite system (BDS) satellites cannot determine their orbits. In this paper, we propose to add a spaceborne annular beam antenna for receiving the global positioning system (GPS) and global navigation satellite system (GLONASS) signals; therefore, the BDS satellites may be capable of determining their orbits by GPS/GLONASS signals. Firstly, the spectrum selection, the power isolation, the range of Doppler frequency shift, and changing rate are taken into account for the feasibility. Specifically, the L2 band signals are chosen for receiving and processing in order to prevent the overlapping of the receiving and transmitting signals. Secondly, the minimum number of visible satellites (MNVS), carrier-to-noise ratio (C/N0), dilution of precision (GDOP), and geometric distance root-mean-square (gdrms) are evaluated for acquiring the effective receiving antennas’ coverage ranges. Finally, the scheme of deploying 3 receiving antennas is proved to be optimal by analysis and simulations over the middle earth orbit (MEO), geostationary earth orbit (GEO), and the inclined geosynchronous satellite orbit (IGSO). The antennas’ structures and patterns are designed to draw a conclusion that installing GPS and GLONASS receivers on BDS satellites for emergent orbits determination is cost-effective.

Artificial satellite orbit computations

1966 ◽  
Vol 25 ◽  
pp. 363-371
Author(s):  
P. Sconzo
Keyword(s):  
Artificial Satellite ◽  
Satellite Orbit ◽  
Artificial Satellites ◽  
Orbital Elements ◽  
Differential Correction ◽  
Gravitational Effects ◽  
Short Intervals ◽  
The Subject ◽  
Introductory Discussion ◽  
Orbit Computation

In this paper an orbit computation program for artificial satellites is presented. This program is operational and it has already been used to compute the orbits of several satellites.After an introductory discussion on the subject of artificial satellite orbit computations, the features of this program are thoroughly explained. In order to achieve the representation of the orbital elements over short intervals of time a drag-free perturbation theory coupled with a differential correction procedure is used, while the long range behavior is obtained empirically. The empirical treatment of the non-gravitational effects upon the satellite motion seems to be very satisfactory. Numerical analysis procedures supporting this treatment and experience gained in using our program are also objects of discussion.

Diminishing Barriers to the Praxis Examination in Communication Sciences and Disorders

2011 ◽  
Vol 1 (2) ◽  
pp. 64-71
Author(s):  
Luis F. Riquelme
Keyword(s):  
Geographic Location ◽  
The United States ◽  
Success For All ◽  
Speech Language Pathology ◽  
Barriers To Success ◽  
Call To Action ◽  
Language Pathology ◽  
National Certification ◽  
Race Ethnicity ◽  
Passing Score

Abstract Passing the Praxis Examination in speech-language pathology or audiology can be a difficult task. A passing score is the entry to a list of requirements for national certification (CCC-SLP, CCC-A) and for state licensure in the United States. This article will provide current information on the examination and address barriers to success that have been identified over the years. A call to action may serve to refocus efforts on improving access to success for all test-takers regardless of race/ethnicity, ability, or geographic location.

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