Multivibrator waveform monitoring system

• US 5,412,623 A
• Filed: 04/01/1994
• Issued: 05/02/1995
• Est. Priority Date: 11/22/1990
• Status: Expired due to Term

• Current Assignee: Japex Geoscience Institute, Inc.
• Original Assignee: Japex Geoscience Institute, Inc.
• Inventors: Nakai, Kazuo, Asada, Masaaki
• Primary Examiner(s): ELDRED, JOHN W
• Application Number:
  US08/221,937
• Time in Patent Office: 396 Days
• Field of Search: 367/189, 367/190, 367/37, 181/108, 181/111, 181/113, 181/114, 181/121, 181/119
• US Class Current: 367/190
• CPC Class Codes: B06B 1/18 wherein the vibrator is actuated by pressure fluid B06B1/20 takes precedence
• CPC Class Codes: G01V 1/135 by deforming or displacing surfaces of enclosures , e.g. by hydraulically driven vibroseis™
• CPC Class Codes: H04R 23/00 Transducers other than those covered by groups H04R9/00 - H04R21/00 diaphragms for transducers of the distributed-mode type H04R7/045

Abstract

A multivibrator waveform monitoring system uses a plurality of seismic energy sources for giving vibrations to strata and a prospector, connected to a geophone, for measuring reflected vibrations. Each of the plurality of seismic energy sources includes a vibrator, a communication unit and a control unit for controlling the starting of the vibrator based on phase difference cancellation information and an operation starting instruction from the prospector. The prospector includes a communication unit and a synchronization control unit for controlling the synchronization of each of the seismic energy sources. The synchronization control unit receives detected information relating to the vibrations of the vibrator by the communication unit, compares a phase difference of vibrations between a master unit which is one of the seismic energy sources and each of slave units which are the rest of the seismic energy sources, calculates phase difference cancellation information for cancelling each phase difference, and transmits the phase difference cancellation information and an operation starting instruction for starting the vibrator by the communication unit. A timing for starting the vibrators of the vibrator for each seismic energy source is adjusted based on the phase difference cancellation information, to thereby make the phase of vibrations of the vibrator of each of the slave seismic energy sources to be the same as the phase of vibrations of the master unit.

Claims

1. A multivibrator waveform monitoring system using a plurality of seismic energy sources for giving vibrations to strata and a prospector, connected to a geophone, for measuring reflected vibrations,

each of said plurality of seismic energy sources including:

communication means for carrying out communications with said prospector;

a vibrator time-swept multifrequency for generating vibrations by changing an oscillation frequency based on a signal from control means;

a detector for detecting a vibration frequency of said vibrator;

a reference signal generator for generating a sweep reference signal which becomes a reference for vibrations of said vibrator; and

said control means, including said reference signal generator, for causing said vibrator to generate the vibration frequency in a phase which is approximate to said sweep reference signal by using a signal that is said sweep reference signal added by a signal fed back from said detector,

said prospector including;

communication means for carrying out communications with said seismic energy source; and

synchronization control means for controlling the synchronization of said seismic energy sources, said synchronization control means receiving, by said communication means, information relating to the vibration frequency of said vibrator detected by said detector of each of said seismic energy sources, calculating a phase difference of variations between one of said plurality of seismic energy sources as a master unit and each of the rest of said seismic energy sources as a slave unit, and sending a calculated phase difference to each slave unit by said communication means, and

means for feeding a phase difference of each slave seismic energy source back to said reference signal generator, for making the phase of vibrations of said vibrator of each of said slave seismic energy sources to be the same as the phase of vibrations of said master unit.

2. A multivibrator waveform monitoring system according to claim 1, wherein a correlation function is calculated between information relating to reflected vibrations from strata received by said geophone and information relating to vibrations of said vibrator detected by said detector of each seismic energy source, to thereby calculate a reflected wave from the underground.