Frequency Domain Analysis of Partial-Tensor Rotating Accelerometer Gravity Gradiometer

Area of Science:

• Geophysics
• Instrumentation
• Signal Processing

Background:

• Traditional rotating accelerometer gravity gradiometer (RAGG) models struggle with signal frequency changes.
• Calibration sensitivity and self-gradient compensation are critical, yet often overlooked, stages in RAGG development.

Purpose of the Study:

• To develop a frequency-domain model for RAGG output influenced by external masses.
• To enhance gravity gradient calculations by considering the RAGG's response to its environment.
• To provide insights for improving RAGG calibration and self-gradient compensation.

Main Methods:

• Established a model based on accelerometer outputs on a rotating disc (RGAA).
• Analyzed RAGG output in the frequency domain when influenced by surrounding masses (particle, sphere, cuboid).
• Developed input-output models using both center gradient and four-accelerometer approaches.

Main Results:

• RAGG output signals, with identical accelerometer scale factors, contain only (4k+2)ω harmonic components.
• The amplitude of these harmonic components is dependent on the orientation of the surrounding mass.
• Input-output models utilizing four accelerometers demonstrate higher accuracy for nearby masses.

Conclusions:

• The four-accelerometer model offers improved accuracy for gravity gradient measurements, especially with proximal masses.
• The study provides a foundation for more effective RAGG calibration and self-gradient compensation strategies.
• Comparative analysis of spherical and cuboid mass influences offers practical guidance for instrument design and application.