In this paper, the authors have designed a set of high torque rigidity stabilizing loops for heavy load Inertial Stabilized Platform, described the control method and introduced the detailed hardware design. Static test and dynamic test are accomplished including the swing table and flight. As a result, the steady-state error of stabilizing loop is ±10.5" in the max disturbed torque, and damping capacity of platform angular rate is better than . The stabilizing loop works well and is reliable. It meets the requirement of the gravity gradient dynamic measurement.

The forward calculation method and the conclusion of the gravity and the gravity gradient variation of the artificial mass body can be used as the mathematical foundation to precisely describe the gravity and gravity gradient variation. It can be used to test and calibrate the gravity gradient measurement device. Compared with the square body mass, the gravity variation generated by the spherical mass is similar to that of the total mass focused on the centroid. It is easy to calculate and apply. For this purpose, the spherical shape artificial mass body is used as the analysis object of gravity excitation to form a forward calculation method.

For solving noise disturbance in marine gravity anomaly measurement and improving accuracy of measurement, FIR low-pass filter technology is applied to high-frequency noise ingredient included in gravity anomaly measurement and the real gravity signal can be recovered. This paper mainly presents the principle and method for designing digital low-pass filter. By applying Discrete Fourier Transform (DFT), different frequency components of both original gravity signal and noise signal are discriminated from this measurement. On the basis of frequency spectrum analysis of gravity measurement, frequency sampling technique is adopted to design low-pass filter and it can well match the gravity measurement signal characteristics. Finally, this method is carried out with previous experimental data. The results demonstrate that the filter designed by frequent sampling method can effectively remove high-frequency noise and the standard error can be within 1mGal.

When the environment temperature changes in the range of 0~40℃, the gravity gradient measuring device should work at 30℃. This requires the use of bidirectional temperature control technology, and the semiconductor refrigeration technology should be applied to gravity meter platform. In this paper, the whole process of the structure design of bidirectional temperature control is introduced, and the method of determining the cooling power is given. In addition, the effects of heat insulation and heat preservation on the accuracy of temperature control, temperature control and the volume of the system are described. The key points of the design are analyzed. The principle and the method of the design of the wind turbine are summarized, and the rationality of the design is verified by the thermal simulation analysis. The design can meet not only the requirement of the system but also the requirement of the high precision of the gravity meter platform.

High resolution accelerometer is a kernel sensor for gravity gradiometer measurement.The QFA is mostly used in this measurement at present,so the requirement of noise performance is very strict.Therefore,a new type low-noise QFA preamplifier is put forward to detect differential capacitor based on constant AC voltage stimulation.On such a basis,the integral servo circuit is designed in combination with the parameters of QFA and servo circuit calibration.The quantitative analysis of the noise influence of servo circuit has been done,the noise contribution of the circuit to the QFA servo system is approximately 1.0×10^-10 g/√Hz(0.5Hz) at 0.5Hz.This can satisfy the needs of gravity gradiometer measurement above 10E resolution.

The gyroscope drift is the main error resource of the inertial stabilized platform. Calibrating and compensating the gyroscope drift is the key to improving the performance of the platform. Because the off-line test results cannot properly illustrate the characteristics of the on-line gyroscopes, calibrating the gyroscope drift in the platform system is necessary. In the geometrical stability state, only the drift affects the platform movement, and the movement can be described with the differential equations. Based on these differential equations, the authors built a set of system state equations, with the drift model coefficients as the state variables. By using the outputs of the accelerometers on the platform as the measurement values, an extended Kalman filter can estimate the drift model coefficients of gyroscopes. The effectiveness and precision of the new test method was evaluated through the simulation.

In this paper, the authors described the temperature characteristics and the method for temperature compensation of the high precision accelerometer. The principle of the influence of temperature on the output characteristics of accelerometer was analyzed in theory and the temperature coefficients of the accelerometer model were calculated by the tests. In order to find out the resolution of the accelerometer to the temperature minimum change and the influence of a large scale change of the temperature, the model temperature coefficients were tested in small distance change at a specific temperature and large distance change. The results of the tests indicate that the input axis misalignment shifts according to a certain rule when the temperature changes. The parameter of the input axis misalignment shifts with the change of temperature was considered when the temperature compensation model of the accelerometer was built, which had never been considered in the other reports. The veracity of the temperature compensation model was validated according to the tests in which the temperatures were changed manually.

Resolution is one of the most important indexes for accelerometer. With the improvement of accelerometer accuracy, the requirement of the resolution accuracy of the accelerometer is improved too. In this situation, the traditional method of resolution test fails to meet the requirement. A method of the resolution test of accelerometer is proposed in this paper, which is based on the double axis tilt method. The test processes and illustration are provided, too. The results indicate that this method can detect the highest resolution of the accelerometer with precision better than 1 μg.

To tackle the emergence of dross during laser cutting quartz glass. The authors studied the influences of laser power, cutting speed and gas pressure on laser cutting dross with single factor experiments, and then optimized the laser cutting parameters by using orthogonal experimental method, so as to mitigate the laser cutting dross. Test results show that this method can avoid the appearance of laser cutting dross caused by improper matching parameters during laser cutting process.

On the basis of introducing the performance requirement that is to be reached in the low-rigidity Quartz Flex Accelerometer's Chip machining, the technical difficulties in machining are brought forward, the polished dressing, etching process, laser cutting and chip coating are analyzed in depth, and the detailed technical realization and corresponding measures are also presented. At last, the main technical points in the working procedure are summarized. The idea of syncretizing the working procedure is also brought forward. The stability is established for the high-performance low-rigidity quartz accelerometer's chip machining.

In the field of oil prospecting, mineral exploration and geological structure research, the gravity method is a commonly used method. The application range of the gravity method mainly depends on the gravimeter. High-precision gravimeter plays an important role in the application and population of the gravity methods. In this paper, the authors present the investigation of a high-precision transportable cold atom gravimeter, which is expected to be used in the field applications. The improved magnetic coils are used in the gravimeter instead of the expensive mu-metal for magnetic shielding. Besides, a portable platform of relatively small size is applied to the vibration isolation. The total interrogation time is optimized to 120 ms and the repetition rate is 2.2 Hz. A sensitivity of and a resolution of within 1000 s integration time have been reached. The continuous measurement of g over 128 hours is carried out. Moreover, a whole seismic wave of about 1 hour that occurred in Pakistan on September 28, 2013 was recorded by the atomic gravimeter. The result coincides well with that recorded by a traditional seismic detector.

Generally, the phase of the cold-atom interferometer is extracted from the atomic interference fringe, which can be obtained by scanning the chirp rate of the Raman lasers at a given interrogation time T. If the phase shift for each T is mapped with a series of measurements, the extraction time is limited by the protocol of each T measurement, and therefore increases dramatically when fine mapping is conducted with a small step of T. In this paper, the authors present a new method for rapid extraction of the phase shift via phase demodulation. By using this method, the systematic shifts can be mapped though the whole interference area. This method enables quick diagnostics of the potential cause of the phase shift in specific time. It is demonstrated experimentally that this method is effective for the evaluation of the systematic errors of the cold atomic gravimeter. The systematic phase error induced by the quadratic Zeeman effect in the free-falling region is extracted by this method. The measured results correspond well with the theoretic prediction and also agree with the results obtained by the fringe fitting method for each T.

The information of the gravity field and gravity gradient reflects the geological information of the Earth's interior. The cold atom interferometer using laser-induced stimulated Raman transitions is one of the most sensitive methods for measuring the gravity and gravity gradient. In order to restrain the noises, one can use two sets of cold atom gravimeters working simultaneously in a system. The common-mode noise in such a system was investigated in detail in this paper. The research on the restraint of the common-mode noise mainly included vibration noise restraint. Moreover, the authors used the ellipse fitting to analyze the common-mode noise and found that the vibration noise can be mostly canceled out in this system.

Because of coast diurnal station beyond control area and seabed diurnal station difficult to place and recover with low security guaranty, marine magnetic survey far beyond the sea is faced with a challenge of diurnal correction problem. The principle of marine magnetic gradient survey and its data characteristics are researched, and a new concept termed as simultaneous survey point is first presented, and a set of precise mathematic model are accordingly produced to calculate diurnal correction alone every survey line.

In March 2015,a ground vehicle gravimetry test was implemented in eastern Changsha to assess the repeatability and accuracy of ground vehicle SINS/GNSS gravimeter-SGA-WZ02.The gravity system developed by NUDT consisted of a Strapdown Inertial Navigation System (SINS),differential Global Navigation Satellite System (GNSS) and a data logging subsystem.A south-north profile of 35 km along the highway in eastern Changsha was chosen and three repeated available measurement lines were obtained.The average speed of a vehicle is 40 km/h.To assess the external ground gravity disturbances,the authors built precise ground gravity data by CG-5 precise gravimeter as the reference.Gravity results in this test from repeated lines show that the internal accuracy is 1.64 mGal for half wavelengths 1.1 km and is 1.12mGal for 1.7 km. The Root-Mean-Square (RMS) of difference between calculated gravity data and reference data is about 2.33 mGal/1.1 km,and 1.77 mGal/1.7 km.

The formula of the relation between gravity anomaly system error and geoid was inferred based on the Stokes formula. To verify the reliability of this relation, the authors designed the simulation experiment based on the EGM2008 gravity model and calculated the propagation of gravity anomaly system error. Using error formula to estimate the accuracy of Stokes geoid will be influenced by the error edge effect. The relation between integral radius and estimated accuracy of the formula is given on the basis of the simulation experiment.

This paper presents the simulation system of gravity gradiometer of rotating accelerometer and, according to the working principle of gravity gradiometer of rotating accelerometer, puts forward the method for gravity gradient signal simulation. The process of simulating gravity gradient signal is as follows: digit signals of accelerometers are produced by computer and gravity gradient is obtained through digit and analog conversion, analog operation, amplification, filter, analog and digit conversion, and modulation. By using this simulation method, the signal characteristics, parameter adjustment, error compensation and signal processing method can be further studied, and the results can serve as references for gravity gradiometer instrument design and development.

The current state of the disk angular position information is obtained by using high-density optical encoder, and the output signal is demodulated by using the angular position information as initial phase angle of gravity gradient demodulation reference signal, then the arithmetic mean of the each demodulation result of gravity gradient information is calculated, and the two groups of gravity gradient information are subjected to smoothed filtering processing respectively. Finally, the gravity gradient demodulation is tested on the Hardware-in-the-Loop simulation platform. The experiment results demonstrate that the gravity gradient signal accuracy is further improved, and the method has such good properties as high practical applicability and maneuverability.

There are various kinds of noises in the raw data observed by airborne gravimetry.Kalman filtering is one of the technologies for obtaining the gravity anomaly from the data.Standard Kalman filtering is capable of obtaining precision gravity anomaly based on accurate statistical noise information,but the noise information is difficult to obtain in practice.Therefore,the measurement noise adaptive Kalman filter based on the analysis of Sage-Husa adaptive Kalman filtering is designed in this paper.Then the adaptive Kalman filter combined with fixed-interval smoother is applied to process simulation data.It can be seen from the simulation result that the errors caused by filter non-convergence are eliminated by fixed-interval smoother.Moreover,compared with the gravity anomaly estimated by standard Kalman filter,accurate gravity anomaly is extracted from the noised data by the adaptive filter when measurement noise information is unknown.

In the forward modeling of the gravity gradient anomaly of complex geological body,the sensitivity matrix is generated,which corresponds to the increase of the memory storage requirement and the time consuming of matrix vector multiplication.On the basis of the wavelet transform theory,the forward data equations in wavelet domain are given firstly,and then the experimental results are compared with the different wavelet basis functions.The numerical simulation experiments show that the Db3 wavelet basis function can effectively reduce the sensitivity matrix of the forward computation in the memory requirements, while reducing the number of matrix vector multiplication.

In this paper, theoretical analysis is made for the influence extent of the rise-and-fall flight on the GT aerial gravity measurement. In order to verify the measurement effect of the rise-and-fall flight, the authors carried out a series of tests on smooth rise-and-fall flight, and made evaluation on the results of aerial gravity smooth rise-and-fall flying measurement performed by GT-2A helicopter and fixed wing helicopter respectively. The results show that the adoption of smooth rise-and-fall flight under the condition of slope not in excess of 3.0° (rate-of-climb about 1/20) is feasible. The coincidence precisions of repeated measurements are exclusively less than 0.7 mGal, thus meeting the requirements of the high-precision measurement.

China's first high-resolution helicopter airborne gravity measuring task adopted low-speed and low-altitude on drape flight. Airborne gravity vibration reduction system is faced with the new helicopter flight platform and flight environment, and a lot of problems concerning the damping system should be resolved. Therefore, the authors conducted data collection and testing for the helicopter airborne gravity vibration reduction system, and the test results obtained can provide the reference basis for the future airborne gravity vibration system design, installation and monitoring.

The terrain correction is one of the important steps to get airborne gravity Bouguer gravity anomaly;nevertheless,the tackling of the problem has a lot of difficulties and troubles.So it is significant to study the terrain correction of airborne gravity.Considering the characteristics of airborne gravity,the authors analyzed the relationship between the selection of the maximum radius in the terrain correlation and the calculation accuracy.In order to meet the requirements of an amount of grid data,the authors made a comparative study of the total resolution terrain partition method,the far and near partition method,and the adaptive quadtree method.The adaptive quadtree method can comprehensively consider the distance and elevation of the terrain cell,realize the best resolution of the terrain,and pick up the calculation speed without the loss of accuracy.

Based on the study of the slope model for gravity and magnetic corresponding analysis,the authors point out that the magnetism-density ratio can effectively determine the lithologic boundary of the geological body.This method was first used in northeastern region of Tibet,the satellite gravity and magnetic data were used to analyze the magnetism-density ratio attribute of deep crust fractures in this region,and the result was verified by seismic data obtained by previous researchers.It is shown that there exists very good corresponding relationship between the magnetism-density ratio and the lithologic transfer interface.

The application of the matched filtering technology to the separation of the deep source field from the shallow source field has been widely used in the processing of gravity and magnetic data. Based on Green's equivalent layer principle, the authors designed a multi-layer Green's equivalent layer model, and then performed fine linear fitting for radial average logarithmic power spectrum, thus realizing the separation of the deep source field from the shallow source field. The comparative analysis of the theoretical model and the practical data shows that this method is simple and practical. It can separate the deep source field from the shallow source field rapidly and effectively in large-area aerial gravity measurement, and can provide important reference basis for the study of the gravity anomaly characteristics and deep structure features, the division of geotectonic units and the determination of the strike of the faulted zone and the geological structure.

In this paper, the authors proposed a rapid detection algorithm to deal with some problems existent in aero geophysical survey, such as failure to update GPS time and data of latitude and longitude, and abnormal magnetic peak caused by external magnetic disturbance. The algorithm utilizes threshold of raw data and its gradients based on characteristics of the observed data to conduct rapid detection. When the jump point is determined, one dimensional interpolation is computed with normal data nodes to replace the jump point. In this paper, the proposed algorithm was accomplished with C++ language. Meanwhile, and other six one-dimensional interpolation fitting methods were calculated for comparison. Moreover, the authors developed plug-in modules for these algorithms on the platform of GeoProbe. The plug-in modules on GeoProbe provide effective tools for the detection and repairing of jump points in airborne geophysical prospecting.

Laplacian of Gaussian Operator with rotation invariance and sensitive to gravity and magnetic field gradient mutation is isotropic second-order differential operator, which has nothing to do with geological boundary objects trend. By calculating the zero value of the Laplacian of Gaussian Operator, the authors delineated the boundary in potential field and extracted geological body distribution, characteristics of fracture structure plane distribution and other geological information. The application of numerical experiments to airborne gravity data indicates that the method can effectively determine the gravity and magnetic source boundaries with higher resolution and accurate positioning. Especially for the multi-sources overlapping geological structure with different depths, different scales and different attitudes, the method can clearly detect the boundaries of weak anomalies with relatively smooth gradient and adjacent local anomalies with superimposed interference. It also can provide more details for further improvement of fine interpretation of the gravity and magnetic local anomalies, and has certain significance for detecting the geological boundaries, devising tectonic units, and determining the fracture zone and the trend of geological structure. All this will facilitate the integrated interpretation.

The method of filling grid dummy values of potential field based on heat conduction model is proposed in this paper, the process of filling grid dummy in blank areas is regarded as a process of heat conduction to achieve grid data transferring from the known effective information to missing data areas, thus gradually completing data interpolation in blank areas. The numerical experiments show the method of filling grid dummy values by heat conduction model has high precision and is obviously effective. The contours are continuous and smooth on the edges, and also can truly reflect the features and trend of abnormal gradients. The application to the real airborne gravity data indicates that the method is feasible and practical, the effect of filling grid dummy can well conform with the variation law and reflect more geological information of regional gravity field, thus improving the accuracy of data processing and transformation in potential field. The method has practical significance.

In order to realize aerogeophysical data service quickly and effectively, the authors studied the Douglas Peucker pumping dilute algorithm and map optimization configuration technology according to characteristics of the track line data. On the basis of the requirements of aeromagnetic survey technical specifications to the yaw pitch, the authors diluted the coordinates to about 1% of the original under the premise of ensuring the basic remain unchanged by setting the thinning thresholds. After the stratification of track line and test area by the measurement scale, the maximum scale of the test area and the minimum scale of the track line were set up, so that the tracks can be clearly distinguished when the scale is larger than a certain scale, and area graphics can be shown only when the scale is smaller than a certain measure. The application of the technology of the thin line extraction and map optimization makes it possible that track line data do not have to be loaded into the computer memory, which accelerates the search speed of the track line and can achieve a fast and effective way to provide flight route data services.