Vibroseis phase-locked control system

Abstract

The invention relates to a vibroseis phase-locked control system which is formed by that a main control unit is respectively connected with a phase-locked control unit and a signal acquisition and output unit which is connected with a vibroseis module. A K-L decomposition filter is realized in an FPGA chip through programming, the influence of an external electromagnetic interference noise on a phase-locked loop is avoided, the anti noise performance of the system is raised, the zero phase shifting filtering of a vibroseis feedback signal is realized, the problems of feedback signal phase detection time offset and zero jump are solved, thus the phase detection accuracy is improved significantly, and the phase accuracy of a phase-locked loop output signal is increased. At the same time, according to the system, a standard signal is generated by a direct frequency synthesizer (DDS), and compared with the existing analog phase-locked loop control scheme, according to the phase control scheme with the combination of the direct frequency synthesizer and digital phase-locked loop technology, the speed of vibroseis phase-locked control is greatly improved.

Description

Technical field: [0001] The invention relates to a control system for seismic exploration, in particular to the phase-locked control of various vibrators using frequency-sweeping excitation signals. Background technique: [0002] The vibroseis, which is widely used in the field of engineering seismic exploration, is a non-explosive source, which can generate excitation signals with controllable waveforms, and use pulse compression technology to concentrate the small energy and long-term excitation wave energy, so as to achieve instantaneous large The energy excites seismic waves. However, in actual seismic exploration, the nonlinearity of the vibroseis system and the coupling between the vibrator substrate and the ground usually cause phase distortion of the vibrator, resulting in a decrease in the signal-to-noise ratio of seismic exploration. The phase distortion of the vibroseis means that the phase of the seismic wave emitted by the vibroseis varies nonlinearly with the ...

AI Technical Summary

Problems solved by technology

Vibrators usually encounter complex and changeable ground conditions during field construction. The existing closed-loop control methods are poorly adaptable to the environment and cannot completely solve the problem of phase distortion of vibrators.

Laing (History and early development of the vibroseis system of seismic exploration. In: Vibroseis (ed. R.L. Geyer), P749–765. SEG) used phase-locked loop control to phase lock the source substrate acceleration signal to the standard source signal phase, but This method uses zero-point detection to compare the phase difference between the feedback signal and the control signal, and sensor noise and electromagnetic interference are likely to cause detection time offset and zero-point jump

Sercel introduces the Kalman adaptive filter in the digital electric control box developed by it to remove the random interference in the feedback signal, but the Kalman adaptive filter is a recursive estimator based on a complex model, so this method has no The system model is highly dependent and cannot fully adapt to complex and changeable geological conditions

The phase-locked loop uses the feedback mechanism to realize the phase tracking of the output signal to the input signal, and there are still many unsolved problems in the vibrator system with complex signal characteristics

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