Method and apparatus for continuous wave seismic prospecting

Claim 1

IN A METHOD OF DETERMINING THE TRAVEL TIME OF SEISMIC WAVES BETWEEN A TRANSMITTING LOCATION AND A RECEIVING LOCATION WHEREIN THERE IS TRANSMITTED FROM THE TRANSMITTING LOCATION AN ELONGATED VIBRATORY SIGNAL MADE UP OF A SUCCESSION OF SEISMIC ENERGY PULSES WHICH ARE TRANSMITTED THROUGH ONE OR MORE RAY PATHS THROUGH THE EARTH FROM THE TRANSMITTING LOCATION TO THE RECEIVING LOCATION, WHICH VIBRATORY SIGNAL IS NONREPETITIVE DURING A TIME INTERVAL WHICH IS AT LEAST AS LONG AS THE TRAVEL TIME OF THE SIGNAL ALONG ANY OF SAID RAY PATHS, AND WHEREIN THERE ARE PRODUCED TIME SERIES RESPECTIVELY REPRESENTATIVE OF THE TRANSMITTED VIBRATORY SIGNAL AND THE COMPOSITE SIGNAL DETECTED AT THE DETECTING LOCATION, AND WHEREIN THE TIME SERIES ARE CROSS-CORRELATED WHILE SHIFTING THE TIME-PHASE RELATIONSHIP THEREOF WITH RESPECT TO THE TIME-PHASE RELATIONSHIP OF TRANSMITTED VIBRATORY SIGNAL AND THE DETECTED COMPOSITE SIGNAL, THE IMPROVEMENT WHICH COMPRISES: PRODUCING A CODE SEQUENCE WHICH MAY BE REPRESENTED AS A REFERENCE TIME SERIES HAVING A UNIQUE AUTOCORRELATION FUNCTION WHICH COMPRISES A SINGLE MAJOR LOBE HAVING NO SIDE LOBES OF GREATER AMPLITUDE THAN THE SIDE LOBES OF THE AUTO-CORRELATION FUNCTION OF STATISTICALLY UNRELATED NOISE COMPONENTS OF THE COMPOSITE SIGNAL DETECTED AT SAID DETECTING LOCATION; AND SHAPING THE AMPLITUDE DENSITY SPECTRUM OF THE PORTION OF THE TIME SERIES PRODUCED BY THE VIBRATORY SEISMIC WAVES TRAVELING FROM SAID TRANSMITTING LOCATION TO SAID RECEIVING LOCATION ALONG ONE OF SAID ONE OR MORE RAY PATHS AND THE TIME SERIES REPRESENTATIVE OF THE TRANSMITTED VIBRATORY SIGNAL IN AN IDENTICAL MANNER TO CORRESPOND TO SAID CODE SEQUENCE.