Abstract: The signal transmitted by Broadband Acoustic Doppler Current Profiler is a kind of pseudo-random coding signal. The impulse signal is a broadband signal due to frequency spectrum spreading. The reverberation signal of BBADCP is processed with quadrature demodulation, while it is difficult to realize because of the required high sampling rate. Digital quadrature sampling of intermediate frequency (IF) signal is used to decrease the sampling rate. According to the requirement of resolving the ambiguity velocity, the broadband reverberation signal is simulated to calculate the velocity of current. The result verifies that the proposed method is appropriate to signal processing of BBADCP.