Source signal correction of high resolution wide band parametric subbottom profiler

Abstract

Because parametric array can generate wide band and narrow beam low frequency signals, it is widely used in high resolution subbottom profiling. Parametric sonar has been one of the most effective equipment in seabed configuration detection and property identification. Emphases of this paper are on source signal correction of wide band parametric subbottom profiler, so we can get desired difference frequency detective signals after non-linear self-demodulation of the wide-band parametric arrays. In order to generate desired Chirp subbottom profiling signal, we have to divide the Chirp waveform which is the envelope of wide-band parametric array's primary wave by its instantaneous frequency. The correction method which is called fragment correction is analyzed subsequently, it is used to correct 1/8 Sine-Square weighted Chirp envelope signal which is a high resolution source signal of subbottom profiler. The expressions of Chirp difference signals after self-demodulation of the wide-band parametric array are derived, and the simplified forms are also proposed at the same time. We can see that the Chirp difference frequency signals with its frequency and bandwidth twice of the primary frequency wave's envelope will be generated by self-demodulation process of wide-band parametric array no matter it was weighted or not. The comparison between expressions before and after simplification indicated that simplify process and the correction methods are all reasonable, computer simulations are given simultaneously. Researches on source signal correction of wide-band parametric array are important in designing source signals of high resolution wide-band parametric subbottom profiling and some other relevant engineering applications.