Effect of sound velocity on time delay estimation based on double beam forming algorithm

In the part of geophysics researches, the method Double Beam Forming (DBF) was found for separating the surface waves from the seismic waves. According to one of the kernels of DBF : extraction of group velocity and phase velocity, this paper benefit from this idea and concentrate on the time delay estimation (TDE) which is one of the key techniques in the array signal processing. The sound velocity is one of the major factor of the TDE, and the DBF image which is built with delay and slowness makes it possible to find the relationship: how the velocity touch the delay. Based on a linear array which is separated into two sub-arrays, the method DBF is applied to simulate data with other two approaches combined: generated cross-correlation (GCC) and generated cross-correlation with phase transform (GCC-PHAT). Thus the research focuses on the sensibility of this factor to TDE, by controlling variables: distance of source, sample frequency, the frequency band. By comparing results of all the cases, we obtain the action of this factor for TDE and analyze the effects in different simulations.