Interference Suppression Analysis of Preparing Gravity Gradient Reference Map in Frequency Domain

Frequency domain and spatial domain are two common methods for calculating gravity gradient from gravity anomalies. Compared with the spatial domain method, the frequency domain preparation of the gravity gradient reference map has the advantages of simple calculation, high efficiency, easy field conversion, and no edge loss, but it will introduce high- frequency interference. This paper proposes a frequency domain transform method that introduces cosine transform into Fourier transform—Fourier cosine transform method. Based on the gravity anomaly data, the six-component gravity gradient reference maps are derived by Fourier transform, cosine transform, and the mentioned Fourier cosine transform method. The preparation effects of the three sets of gravity gradient reference maps are compared. At the same time, the power spectrum density is used to analyze the interference suppression effects of the three methods. The reference maps of the gravity gradient obtained by the three methods show that Fourier method and the Fourier cosine transform method have similar features, and the latter method has superior interference suppression effects. Cosine transform will cause edge information loss and information offset. The result of power spectrum density also shows that the proposed Fourier cosine transform method has the best interference suppression effect.