Process for measuring the sampled amplitude of a seismic signal

Claim 1

In a process for measuring the instantaneous amplitude of a seismic signal received by a sensing device after the said signal has travelled through a continuous medium, in which the amplitude of the signal received by the sensor is sampled at periodic times, emission of the signal from a signal source into the continuous medium occurring in the form of a sequence of energy impulses spaced out in time in accordance with a predetermined pattern, the improvement wherein A. an elementary unit of time is set up by means of a clock, B. a synchronization signal is given at the end of each elementary time unit, C. the number of synchronizing signals thus emitted is counted in an adding counter, D. the content of the said adding counter for each basic unit of time is compared in turn with the contents of each memory in a first series of memories in which are recorded the numbers defining the instants at which an energy impulses is to be emitted, E. When the comparison shows equality a signal for the emission of energy is given, F. the instantaneous value, at the instant of sampling, of the energy detected by a sensor after reflection against the discontinuities of the continuous medium and converted into a digital sample form is received in another series of memories consisting of a number of elements, each of which is identified by an address, G. each sample is given a number of addresses determined by the instant of sampling and the various instants at which previous emissions have taken place, the said emissions being separated from the instant of sampling by a period lasting not more than the maximum time taken by the signal to travel through the continuous medium from signal source to sensor.

Claim 5

A device for measuring the instantaneous amplitude of a seismic signal after it has travelled through a continuous medium, said signal being introduced into said medium by a signal source as a predetermined pattern in time of energy impulses, a sensor being connected to measure the amplitude of a resulting signal in said medium, comprising A. a first series of memories, each of which can store a given number of digits, in which is recorded, in digital form, data defining the series of instants at which each of the sequence of impulse emissions is to take place, B. a second series of memories with the same composition as the first series for recording a sequence of possible emission instants, the said sequence of possible emission instants being confined to a period which is at most equal to the maximum travelling time of a signal from said signal sources to said sensor, C. a third series of memories with the same composition as the previous series for registering sampled digital values of the signal received by the sensor, said sampled values being sampled for each basic time unit, digitally coded and addressed to the different memories according to the temporal position of the signal sample relative to the instants of emission preceding the instant of sampling with a period shorter than the maximum time taken for the waves to travel through the medium, the said instants being contained at the instant under consideration in the second series of memories, D. an arithmetic unit for carrying out additions and subtractions, connected at each arrival of a sample to the second series of memories, for determining the addresses to which the incoming sample is to be directed, operative by being connected to the corresponding memories in the third series to fetch from each memory in turn the values contained in them, to add up in turn the values fetched and the values of the sample and to redirect the resulting sum to the memory from which the values were fetched, E. a synchronization generator for defining the basic time unit and for emitting a synchronization signal for each basic time unit, F. an adding counter receiving the synchronization signals and defining the time that has passed since the start of the operation, G. a digital comparator for receiving the content of the adding counter and the contents in turn of the different memories in the first series, and when equality occurs between its two received values, for setting off an impulse, H. a transfer unit connected in turn to the different memories in the first series and cyclically to the different memories in the second series for having connection of the different memories with one another through the transfer unit effected by the digital comparator whenever said comparator registers equality, I. a subtracting counter for receiving the content of the adding counter and for subtracting therefrom a finite number corresponding to the value in basic time units of the maximum time taken by the waves to travel through the medium, J. a second digital comparator for receiving the content of the subtracting counter and in turn, through a connection unit, the contents of the memories in the second series, and for re-setting to zero, after a certain time, the content of the memory in the second series to which connection was made and changing over to the next memory, the arithmetic unit receiving the content of the adding counter and working out the difference between the instantaneous content of the adding counter and each of the series of contents of the memories in the second series in turn, the basic time unit generator controlling a sampler, which determines the instantaneous value of the signal received by the group of sensors sensitive to the seismic signal, transferrinG this value to an analogue-to-digital converter, this digital value subsequently being transferred to the arithmetic unit, the said arithmetic unit computing the differences in turn between the content of the adding counter and the different contents of the memories in the second series, determining the memories of the third series, the positions of which correspond to the differences computed, the said arithmetic unit then fetching in turn the contents of the memories thus determined, producing the sum of the contents of these different memories and of the digital value of the signal at the instant under consideration, the results and sums being redirected into the corresponding memories.

Claim 6

A device for measuring the instantaneous amplitude of a seismic signal after it has travelled through a continuous medium, said signal being introduced into said medium by a signal source as a predetermined pattern in time of energy impulses, a sensor being connected to measure the amplitude of a resulting signal in said medium, comprising A. a first series of memories, each of which can store a given number of digits, in which is recorded, in digital form, data defining the series of instants at which each of the sequence of impulse emissions is to take place, B. a second series of memories with the same composition as the first series for recording a sequence of possible emission instants, the said sequence of possible emission instants being confined to a period which is at most equal to the maximum travelling time of a signal from said signal sources to said sensor, C. a third series of memories with the same composition as the previous series for registering sampled digital values of the signal received by the sensor, said sampled values being sampled for each basic time unit, digitally coded and addressed to the different memories according to the temporal position of the signal sample relative to the instants of emission preceding the instant of sampling with a period shorter than the maximum time taken for the waves to travel through the medium, the said instants being contained at the instant under consideration in the second series of memories, D. an arithmetic unit for carrying out additions and subtractions, connected at each arrival of a sample to the second series of memories, for determining the addresses to which the incoming sample is to be directed, operative by being connected to the corresponding memories in the third series to fetch from each memory in turn the values contained in them, to add up in turn the values fetched and the values of the sample and to redirect the resulting sum to the memory from which the values were fetched, E. a synchronization generator for defining the basic time unit and for emitting a synchronization signal for each basic time unit, F. an adding counter receiving the synchronization signals and defining the time that has passed since the start of the operation, G. a digital comparator for receiving the content of the adding counter and the contents in turn of the different memories in the first series, and when equality occurs between its two received values, for setting off an impulse, H. a transfer unit connected in turn to the different memories in the first series and cyclically to the different memories in the second series for having connection of the different memories with one another through the transfer unit effected by the digital comparator whenever said comparator registers equality, I. a subtracting counter for receiving the content of the adding counter and for subtracting therefrom a finite number corresponding to the value in basic time units of the maximum time taken by the waves to travel through the medium, J. a second digital comparator for receiving the content of the subtracting counter and in turn, through a connection unit, the contents of the memories in the second series, and for re-setting to zero, after a certain time, the content of the memory in the second series to which connection was made and changing over to the next memory, the arithmetic unit receiving the content of the adding counter and working out the difference between the instantaneous content of the adding counter and each of the series of contents of the memories in the second series in turn, the basic time unit generator controlling a sampler, which determines the instantaneous value of the signal received by the group of sensors sensitive to the seismic signal, transferrinG this value to an analogue-to-digital converter, this digital value subsequently being transferred to the arithmetic unit, the said arithmetic unit computing the differences in turn between the content of the adding counter and the different contents of the memories in the second series, determining the memories of the third series, the positions of which correspond to the differences computed, the said arithmetic unit then fetching in turn the contents of the memories thus determined, producing the sum of the contents of these different memories and of the digital value of the signal at the instant under consideration, the results and sums being redirected into the corresponding memories.

Claim 14

A device for processing received signals which occur as a result of transmitted impulses, said impulses occuring not more than a predetermined time prior to said received signals, comprising; A. clock means for generating a train of synchronization pulse signals defining a corresponding train of elementary equal time intervals, B. means responsive to said synchronization pulse signals for sensing sample values of said received signals at instants of time defined by said synchronization pulse signals, C. analog-to-digital conversion means for converting the sample values thus sensed to digital values, D. counter means responsive to said synchronization pulses for measuring the elapsed time from the respective instants of transmission of each of said impulses until the respective instants when said sample values are sensed to determine the integral number of elementary time units which have elapsed, E. a plurality of memory means for totalling the respective digital sample values in a corresponding plurality of categories, each category including as addends all and only those samples which occurred a respective predetermined integral number of time units after the transmission of any one of said impulses, the number of said categories and the corresponding number of said memory means being limited by an integral number of elementary time units sufficient to receive all signals of interest from a given impulse, and F. means for recording the totalled digital sample values from the respective categories after a complete predetermined time pattern of impulses have been transmitted and the resulting received signals sampled.

Claim 15

A device for processing received signals which occur as a result of transmitted impulses, said impulses occuring not more than a predetermined time prior to said received signals, comprising; A. clock means for generating a train of synchronization pulse signals defining a corresponding train of elementary equal time intervals, B. means responsive to said synchronization pulse signals for sensing sample values of said received signals at instants of time defined by said synchronization pulse signals, C. analog-to-digital conversion means for converting the sample values thus sensed to digital values, D. counter means responsive to said synchronization pulses for measuring the elapsed time from the respective instants of transmission of each of said impulses until the respective instants when said sample values are sensed to determine the integral number of elementary time units which have elapsed, E. a plurality of memory means for totalling the respective digital sample values in a corresponding plurality of categories, each category including as addends all and only those samples which occurred a respective predetermined integral number of time units after the transmission of any one of said impulses, the number of said categories and the corresponding number of said memory means being limited by an integral number of elementary time units sufficient to receive all signals of interest from a given impulse, and F. means for recording the totalled digital sample values from the respective categories after a complete predetermined time pattern of impulses have been transmitted and the resulting received signals sampled.