The output model of a rotating accelerometer gravity gradiometer (RAGG) established by the inertial dynamics method cannot reflect the change of signal frequency, and calibration sensitivity and self-gradient compensation effect for the RAGG is a very important stage in the development process that cannot be omitted. In this study, a model based on the outputs of accelerometers on the disc of RGAA is established to calculate the gravity gradient corresponding to the distance, through the study of the RAGG output influenced by a surrounding mass in the frequency domain. Taking particle, sphere, and cuboid as examples, the input-output models of gravity gradiometer are established based on the center gradient and four accelerometers, respectively. Simulation results show that, if the scale factors of the four accelerometers on the disk are the same, the output signal of the RAGG only contains (4k+2)ω (ω is the spin frequency of disc for RAGG) harmonic components, and its amplitude is related to the orientation of the surrounding mass. Based on the results of numerical simulation of the three models, if the surrounding mass is close to the RAGG, the input-output models of gravity gradiometer are more accurate based on the four accelerometers. Finally, some advantages and disadvantages of cuboid and sphere are compared and some suggestions related to calibration and self-gradient compensation are given.
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http://dx.doi.org/10.3390/s21051925 | DOI Listing |
Sensors (Basel)
February 2024
Science and Technology on Vacuum Technology and Physics Laboratory, Lanzhou Institute of Physics, Lanzhou 730000, China.
The performance of the capacitive gap-sensing system plays a critical role in a satellite-based gravity gradiometer that is developed using an electrostatic accelerometer. The capacitive sensing gain mainly depends on the stabilized injection bias amplitude, the gain of the transformer bridge, and the trans-impedance amplifier. Previous studies have indicated that amplitude noise is the main factor influencing the noise of capacitive displacement detection.
View Article and Find Full Text PDFEllipse fitting is widely used in the extraction of the differential phase between atom interferometers amid substantial common phase noise. This study meticulously examines the dependency of extraction noise on the differential phase between atom interferometers during ellipse fitting. It reveals that the minimum extraction noise can manifest at distinct differential phases, contingent upon the dominance of different noise types.
View Article and Find Full Text PDFPhys Rev Lett
September 2023
Dipartimento di Fisica e Astronomia and LENS, Università di Firenze, INFN Sezione di Firenze, via Sansone 1, I-50019 Sesto Fiorentino (FI), Italy.
We demonstrate a novel scheme for Raman-pulse and Bragg-pulse atom interferometry based on the 5S-6P blue transitions of ^{87}Rb that provides an increase by a factor ∼2 of the interferometer phase due to accelerations with respect to the commonly used infrared transition at 780 nm. A narrow-linewidth laser system generating more than 1 W of light in the 420-422 nm range was developed for this purpose. Used as a cold-atom gravity gradiometer, our Raman interferometer attains a stability to differential acceleration measurements of 1×10^{-8} g at 1 s and 2×10^{-10} g after 2000 s of integration time.
View Article and Find Full Text PDFRev Sci Instrum
June 2022
Xcalibur Multiphysics, 10 Compass Road, Jandakot, WA 6164, Australia.
Vibration in the audio frequency band affects the performance of rotating gravity gradiometers used for airborne mineral exploration. This is probably due to translation to rotation coupling inside the gradiometer platform. It was found that the DC gravity gradient signal was proportional to the square of the third time derivative of position, or jerk squared.
View Article and Find Full Text PDFSci Rep
May 2022
Lockheed Martin RMS - Gravity Systems, 2221 Niagara Falls Boulevard, Niagara Falls, NY, 14304, USA.
The first analytical evaluation of a free-hinged-hinged-hinged-free beam proposed for use as the primary sensing element of a new gravity gradiometer is presented. Results of the evaluation obtained in quadratures are applied to the beam's structure, including locating the hinges that form the beam's boundary conditions allowing only free rotations around its nodal axes. These are deliberately chosen to minimize the beam's symmetric free ends deflections under the uniform body loading of gravity while simultaneously permitting the beam's maximum possible mirror-symmetric free ends deflections owing to a gravity gradient distributed along its length.
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