Method and device for acquiring data clock by seismograph

Abstract

The invention provides a method and device for acquiring a data clock by a seismograph. The method includes: carrying out band-pass filtering on the obtained underwater acoustic time scale signal, obtaining the filtered underwater acoustic time scale signal, carrying out fractional order Fourier transform on the filtered underwater acoustic time scale signal, and calculating the optimal rotation angle of the underwater acoustic time scale signal; intercepting the filtered underwater acoustic time scale signal to obtain the maximum amplitude of arrival time of the underwater acoustic time scalesignal each time, and determining the clock deviation in the seismograph at the interval time by utilizing the maximum amplitude deviation of the underwater acoustic time scale signal every two times; performing resampling correction on the acquired data according to the internal clock deviation; and obtaining clock synchronization data. According to the invention, a linear frequency modulation signal with a large time-bandwidth product is applied to an underwater acoustic time scale signal as a pulse compression signal, the influence of complexity and multipath effect of a marine environmentis overcome, the interference of a single frequency point is suppressed by transmitting a linear frequency modulation signal in a timing manner for multiple times, and the signal is ensured to have abetter signal-to-noise ratio under the condition of a long distance.

Description

technical field [0001] The invention relates to the technical field of seabed geophysical detection, in particular to a method and device for collecting data clocks by seismographs. Background technique [0002] Submarine geophysical detection equipment, especially the Ocean Bottom Seismometer (OBS for short) and the submarine seismic acquisition node (OBN) often require multiple or even hundreds of instruments to operate at the same time, and each instrument is independent. For acquisition operations, due to the rapid attenuation of electromagnetic waves in seawater, submarine equipment cannot receive GPS clock signals. Before offshore operations, submarine detection equipment can only perform GPS clocking operations before launching and after recovery. After the instrument is launched into the sea, it always relies on the internal clock. Timing data collection, so the internal clock accuracy has become a key condition affecting the accuracy of data collection. At present, ...

AI Technical Summary

Problems solved by technology

However, in practical applications, on the one hand, due to the strong time-varying and space-varying effects of underwater acoustic signals, the complexity of the ocean environment, and multipath effects, single-frequency signals are often submerged in reverberation and noise as the distance increases. In addition, the Doppler frequency shift effect is obvious, the signal-to-noise ratio is low, and the working distance is short.

On the other hand, the traditional discrete Fourier transform (DFT) analysis method for underwater acoustic signal recognition can only provide the overall characteristic information of the transformed signal in a single domain (time domain or frequency domain), and does not include the signal All useful signals, only suitable for analyzing deterministic and stationary signals

For the complex environment of the ocean, the signal at a single frequency point is often interfered by noise, and it is difficult to extract accurate signal arrival information using this method

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