Frequency Shift Processing for the Hypocenter with Short-term Single-frequency Pulse in the Ocean Sub-bottom Profile Data

The spatial aliasing of waveform data which is recorded using the short-term single-frequency pulse in the sub-bottom profile is serious. Usually the instantaneous amplitude attribute(signal envelope) is extracted for interpretation using the Hilbert transform for its signal has a characteristic of high frequency and narrow-band. However, instantaneous amplitude is always positive, so it is not convenient to use when performing structural interpretation. In this paper, on the basis of the extraction of instantaneous amplitude in the sub-bottom profile data, calculating the differential of instantaneous amplitude cooperated the filtering achieve frequency shift processing for high-frequency narrow-band signal in sub-bottom section. This method converts a multi-cycle signal with high-frequency narrow-band to a Single-cycle signal with low-frequency bandwidth, which effectively extends the octave and eliminates aliasing. Application in the South China sea sub-bottom profile data, the data is more conducive to structural interpretation.