We discuss two methods to combine the pressure and velocity detectors at an identical location on a 2D OBC line. Both methods perform a calibration over the velocity detector or geophone. The goal of both of these methods is to eliminate the ghost reflection. The first method is in the time domain and combines the geophone calibration and the deghosting in one step. The second method is in the frequency domain and performs the geophone calibration and the deghosting in two steps.