2D GPR monitoring without a source by interferometry in a 3D world

Creating virtual sources at locations where physical receivers have measured a response is known as seismic interferometry. The method does not use any information about the actual source´s location. The source can be mobile phone radiation, already available in the air, as long as this background radiation can be represented by uncorrelated noise sources. Interferometry by multi-dimensional deconvolution (MDD) `divides the common path out of the data´, resulting in amplitude and phase information. Meanwhile, interferometry by cross-correlation (CC) uses time-reversion to retrieve phase information only. CC works fine for low-dissipative media. A finite difference time-domain solver can create 3D line-array data of receiving antennas on a surface of which the subsurface is homogeneous perpendicular to this receiver-array, without having anything being transmitted, other than background radiation. By applying the MDD and CC techniques, the 2D GPR signal can be retrieved as if there would be a transmitting antenna at a receiving antenna´s position. Numerical results show that both MDD and CC work well.