A case study of the application of GPS to lunar laser ranging timing systems

2018 ◽  
Vol 12 (4) ◽  
pp. 279-287
Author(s):  
C. Munghemezulu ◽  
L. Combrinck ◽  
O. J. Botai
Keyword(s):  
Global Positioning System ◽  
Frequency Standard ◽  
Laser Ranging ◽  
Positioning System ◽  
Lunar Laser Ranging ◽  
Frequency Standards ◽  
Lunar Laser ◽  
Timing System ◽  
Global Positioning ◽  
Rubidium Clock

Abstract The Hartebeesthoek Radio Astronomy Observatory is currently building a Lunar Laser Ranging station. This geodetic technique requires a good timing system to measure a round trip of laser photons from the telescope to the Moon and back to the telescope. We test the newly acquired timing system using examples of the Global Positioning System applications. Data in Receiver Independent Exchange Format was processed using GAMIT/GLOBK software. The results were compared against those derived from the Global Positioning System receivers that were integrated with a frequency standard from a hydrogen maser and a standard internal quartz. The results indicate that (i) the rubidium clock operates optimally and the clock drifted to within error margins of sub-centimetre level during the period of 2.5 seconds, (ii) the selected site for the permanent installation of the timing antenna has minimal multipath effect and (iii) we observed no improvement in Global Positioning System products derived from receivers that were integrated with different frequency standards.

scholarly journals Introduction of JD 19: Nutation

1995 ◽  
Vol 10 ◽  
pp. 209-213
Author(s):  
V. Dehant
Keyword(s):  
Global Positioning System ◽  
Laser Ranging ◽  
Lunar Laser Ranging ◽  
Long Baseline ◽  
Lunar Laser ◽  
Global Positioning ◽  
Nutation Series ◽  
Precise Time ◽  
Better Than ◽  
Precession Constant

Due to both precise time measurements and precise geodetic positioning methods (like Very Long Baseline Interferometry (VLBI), Lunar Laser Ranging (LLR), Satellite Laser Ranging (SLR) and Global Positioning System (GPS)), the position of the instantaneous axis of the Earth’s rotation in space is measured with a precision better than a tenth of milliarcsecond. Simultaneously the amplitudes of the nutations of the Celestial Ephemeris Pole (CEP) deduced from the observations, i.e. the periodic motions in space of the CEP due to the luni-solar attraction or to other planetary attractions, have also been improved. However, these observed nutation amplitudes differ with respect to the computated ones based on an elliptical, uniformly rotating and deformable Earth responding to the lunar and solar attractions, as adopted by the IAU in 1980. The first session on “Observations and data reduction” dealt with Earth’s orientation observations and data analysis for deriving precession and nutations, as well as the associated residuals with respect to the adopted precession constant and nutation series. Comparisons between the different results have been presented including in-phase and out-of-phase components of the prograde and retrograde nutations or of nutations in longitude and in obliquity (see Session 1 of our JD: Newhall et al., McCarthy and Luzum, Herring, and Session 2: Gross). These differences “observed - adopted” nutations achieve several milliarcseconds and exhibit periodic as well as secular characteristics.

scholarly journals Current Status and Future Directions of the IERS RS/PC Predictions of UT1

2009 ◽  
Vol 5 (H15) ◽  
pp. 218-218 ◽  
Author(s):  
W. Wooden ◽  
B. Luzum ◽  
N. Stamatakos
Keyword(s):  
Global Positioning System ◽  
Very Long Baseline Interferometry ◽  
Current Status ◽  
Laser Ranging ◽  
Positioning System ◽  
Reference Systems ◽  
Future Directions ◽  
Long Baseline ◽  
Global Positioning ◽  
E Mail

The International Earth Rotation and Reference Systems Service (IERS) Rapid Service/Prediction Center (RS/PC) produces daily and weekly EOP combination and prediction solutions. The daily solutions are produced after 1700 UTC while the weekly EOP solutions are produced Thursday after 1700 UTC. These solutions include data from Atmospheric Angular Momentum (AAM) analysis and forecasts, Global Positioning System (GPS) solutions, Satellite Laser Ranging (SLR) solutions, and Very Long Baseline Interferometry (VLBI) solutions. The solutions are sent to roughly 700 people by e-mail per week and are picked up in roughly 40000 ftp downloads per month.

scholarly journals SPACE-BASED TESTS OF GRAVITY WITH LASER RANGING

2007 ◽  
Vol 16 (12a) ◽  
pp. 2165-2179 ◽  
Author(s):  
SLAVA G. TURYSHEV ◽  
JAMES G. WILLIAMS
Keyword(s):  
Laser Ranging ◽  
Lunar Laser Ranging ◽  
Fundamental Physics ◽  
Entire Area ◽  
Geodetic Precession ◽  
Frequency Standards ◽  
Lunar Laser ◽  
Ppn Parameters ◽  
Precision Frequency ◽  
Tests Of Gravity

Existing capabilities of laser ranging, optical interferometry, and metrology, in combination with precision frequency standards, atom-based quantum sensors, and drag-free technologies, are critical for space-based tests of fundamental physics; as a result of the recent progress in these disciplines, the entire area is poised for major advances. Thus, accurate ranging to the Moon and Mars will provide significant improvements in several gravity tests, namely the equivalence principle, geodetic precession, PPN parameters β and γ, and possible variation of the gravitational constant G. Other tests will become possible with the development of an optical architecture that allows one to proceed from meter to centimeter to millimeter range accuracies on interplanetary distances. Motivated by anticipated accuracy gains, we discuss the recent renaissance in lunar laser ranging and consider future relativistic gravity experiments with precision laser ranging over interplanetary distances.

scholarly journals Earth rotation from radio interferometric tracking of GPS satellites

1988 ◽  
Vol 128 ◽  
pp. 209-213 ◽  
Author(s):  
R. I. Abbot ◽  
R. W. King ◽  
Y. Bock ◽  
C. C. Counselman
Keyword(s):  
Earth Rotation ◽  
Pole Position ◽  
Laser Ranging ◽  
Lunar Laser Ranging ◽  
Gravitational Forces ◽  
Long Baseline ◽  
Gps Satellites ◽  
Lunar Laser ◽  
Global Positioning ◽  
A New Technique

Radio-interferometric tracking of the Global Positioning System (GPS) satellites offers a new technique for regular monitoring of variations in the earth's rotation. The observations are sensitive to pole position and length-of-day, at a level of precision which may make this technique competitive with satellite and lunar laser ranging and very long baseline interferometry (VLBI). The present limitations are the number of satellites and tracking stations available and inadequate modeling of non-gravitational forces on the satellites. The potential advantages are rapid turn-around and minimal incremental cost. We have performed a preliminary analysis using six days of observations from a four-station network. Comparison of earth rotation values from our GPS analysis with values obtained by VLBI and laser ranging reveals differences after five days of 0.9 ms in UT1, 0.04″ in x and 0.07″ in y. These differences reflect errors in the GPS determinations due primarily to inadequate modeling of non-gravitational forces.

Aplikasi Pemosisi Lokal Berbasis Android Dengan Menggunakan GPS

INTI TALAFA ◽  
2018 ◽  
Vol 8 (2) ◽  
Author(s):  
Yaman Khaeruzzaman
Keyword(s):  
Global Positioning System ◽  
Positioning System ◽  
Database Server ◽  
Global Positioning

Seiring dengan pesatnya kemajuan teknologi saat ini, kebutuhan manusia menjadi lebih beragam, termasuk kebutuhan akan informasi. Tidak hanya media informasinya yang semakin beragam, jenis informasi yang dibutuhkan juga semakin beragam, salah satunya adalah kebutuhan informasi akan posisi kita terhadap lingkungan sekitar. Untuk memenuhi kebutuhan itu sebuah sistem pemosisi diciptakan. Sistem pemosisi yang banyak digunakan saat ini cenderung berfokus pada lingkup ruang yang besar (global) padahal, dalam lingkup ruang yang lebih kecil (lokal) sebuah sistem pemosisi juga diperlukan, seperti di ruang-ruang terbuka umum (taman atau kebun), ataupun dalam sebuah bangunan. Sistem pemosisi lokal yang ada saat ini sering kali membutuhkan infrastruktur yang mahal dalam pembangunannya. Aplikasi Pemosisi Lokal Berbasis Android dengan Menggunakan GPS ini adalah sebuah aplikasi yang dibangun untuk memenuhi kebutuhan pengguna akan informasi lokasi dan posisi mereka terhadap lingkungan di sekitarnya dalam lingkup ruang yang lebih kecil (lokal) dengan memanfaatkan perangkat GPS (Global Positioning System) yang telah tertanam dalam perangkat smartphone Android agar infrastruktur yang dibutuhkan lebih efisien. Dalam implementasinya, Aplikasi Pemosisi Lokal ini bertindak sebagai klien dengan dukungan sebuah Database Server yang berfungsi sebagai media penyimpanan data serta sumber referensi informasi yang dapat diakses melalui jaringan internet sehingga tercipta sebuah sistem yang terintegrasi secara global. Kata kunci: aplikasi, informasi, pemosisi, GPS.

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