Noise-suppression method

Claim 3

The method as defined in claim 1 wherein such offending seismic signals and all subsequent seismic signals are suppressed for a predetermined time period following the onset of said offending seismic signals.

Claim 4

The method as defined in claim 1, wherein the amplitude level of said received seismic signal train is sampled at desired intervals to form a time-scale recording of digital data samples, including the further steps of: comparing each said data sample with a digital representation of the reference model corresponding to the time window encompassing said data sample; and suppressing offending data samples whose amplitude level exceeds the level of said reference model.

Claim 5

The method as defined in claim 3 wherein said offending data sample and a predetermined number of subsequent data samples are suppressed.

Claim 6

The improved noise suppression method as defined in claim 1 wherein the step of selecting includes the steps of: determining the median within each set of combined seismic signals; and selecting the largest average absolute magnitude within each set that lies between the limits of the median and a multiple of the median.

Claim 7

An improved apparatus for enhancing the signal-to-noise ratio of a train of seismic signals received by a recording system in response to an acoustic excitation of the earth, said recording system including means for sampling, quantizing formatting, summing and recording seismic signals received during normal recording cycles comprising: means for setting the recording system to initialize a first reference-model-building cycle at a first desired location including means for generating a plurality of seismic-signal time scale recordings in response to earth excitations at said first desired location; a sample counter for grouping the signals of each said time scale recording within a plurality of consecutive time windows; means for averaging the absolute amplitudes of the signals contained within each said time window of the respective time scale recordings to provide a set of average absolute amplitudes for each said time window; means for selecting a desired one of said averaged absolute amplitudes from each said set; means for multiplying the selected average absolute amplitudes by a predetermined coefficient to provide a reference model of the expected amplitude level of a valid seismic signal for each said time window; a storage for receiving said reference models; means for resetting said recording system to execute a normal recording cycle; means for comparing seismic signals received during said normal recording cycle with the stored reference models corresponding to respective time windows containing the received seismic signals; and means for rejecting, prior to summing, seismic signals whose amplitude level exceeds the reference-mode amplitude.

Claim 8

An improved apparatus for enhancing the signal-to-noise ratio of a train of seismic signals received by a recording system in response to an acoustic excitation of the earth, said recording system including means for sampling, quantizing formatting, summing and recording seismic signals received during normal recording cycles comprising: means for setting the recording system to initialize a first reference-model-building cycle at a first desired location including means for generating a plurality of seismic-signal time scale recordings in response to earth excitations at said first desired location; a sample counter for grouping the signals of each said time scale recording within a plurality of consecutive time windows; means for averaging the absolute amplitudes of the signals contained within each said time window of the respective time scale recordings to provide a set of average absolute amplitudes for each said time window; means for selecting a desired one of said averaged absolute amplitudes from each said set; means for multiplying the selected average absolute amplitudes by a predetermined coefficient to provide a reference model of the expected amplitude level of a valid seismic signal for each said time window; a storage for receiving said reference models; means for resetting said recording system to execute a normal recording cycle; means for comparing seismic signals received during said normal recording cycle with the stored reference models corresponding to respective time windows containing the received seismic signals; and means for rejecting, prior to summing, seismic signals whose amplitude level exceeds the reference-mode amplitude.

Claim 9

The apparatus as defined in claim 6 wherein said selecting means further comprises: means for selecting the median average absolute magnitude from each set; and means for selecting the largest average amplitude from eash said set that lies between the median and an integral multiple of the median.

Claim 10

An improved apparatus for enhancing the signal-to-noise ratio of a train of seismic signals received by a recording system in response to an acoustic excitation of the earth, said recording system including means for sampling, gain-conditioning, quantizing, summing and recording seismic signals received during normal recording cycles, comprising: an initialization switch for setting the recording system to initialize a first reference-model-building cycle at a desired location including means for generating a plurality of seismic-signal time scale recordings in response to earth excitations at said desired location; a formatter coupled to said recording system for converting said quantized signal samples to absolute values; a sample counter coupled to said formatter for receiving and grouping the signals of each said time scale recording within a plurality of consecutive time windows; an accumulator/multiplier for averaging the absolute amplitudes of signals received from said counter, contained within each said time window of the respective time scale recordings, to provide a set of average absolute amplitudes for each said time window; a selector for extracting a desired one of said averaged absolute amplitudes from each said set; a shift register for augmenting said extracted average absolute amplitude by a predetermined coefficient to provide a reference model of the expected amplitude level of a valid seismic signal for each said time window; a storage for receiving said reference models; a reset switch for resetting said recording system to execute a normal recording cycle; a comparator for comparing quantized seismic signal samples received during said normal recording cycle with the stored reference models corresponding to respective time windows containing the received seismic signals; and a suppress-sum counter for rejecting, prior to summing, quantized seismic signal samples whose amplitude level exceeds that of the reference-model.

Claim 11

An improved apparatus for enhancing the signal-to-noise ratio of a train of seismic signals received by a recording system in response to an acoustic excitation of the earth, said recording system including means for sampling, gain-conditioning, quantizing, summing and recording seismic signals received during normal recording cycles, comprising: an initialization switch for setting the recording system to initialize a first reference-model-building cycle at a desired location including means for generating a plurality of seismic-signal time scale recordings in response to earth excitations at said desired location; a formatter coupled to said recording system for converting said quantized signal samples to absolute values; a sample counter coupled to said formatter for receiving and grouping the signals of each said time scale recording within a plurality of consecutive time windows; an accumulator/multiplier for averaging the absolute amplitudes of signals received from said counter, contained within each said time window of the respective time scale recordings, to provide a set of average absolute amplitudes for each said time window; a selector for extracting a desired one of said averaged absolute amplitudes from each said set; a shift register for augmenting said extracted average absolute amplitude by a predetermined coefficient to provide a reference model of the expected amplitude level of a valid seismic signal for each said time window; a storage for receiving said reference models; a reset switch for resetting said recording system to execute a normal recording cycle; a comparator for comparing quantized seismic signal samples received during said normal recording cycle with the stored reference models corresponding to respective time windows containing the received seismic signals; and a suppress-sum counter for rejecting, prior to summing, quantized seismic signal samples whose amplitude level exceeds that of the reference-model.

Claim 12

The apparatus as defined in claim 6 wherein said recording system includes means for converting said received signals to digital data samples whose level is representative of the signal amplitude level, said apparatus further comprising: a comparator for comparing each said digital data sample with a digital representation of the level of the reference model that is appropriate to the time window including said sample; a suppress-sum counter, coupled to said comparator, for suppressing, prior to summing, offending samples whose level exceeds the reference model level.

Claim 13

The apparatus as defined in claim 9 further comprising: a sample counter interconnected with said comparator and said suppressing means for suppressing a desired number of data samples following an offending data sample.

Claim 14

The apparatus as defined in claim 1 further comprising: means for automatically initializing other reference-model-building cycles at other desired locations concurrently with a normal recording cycle.

Claim 15

The improved noise suppression method as defined in claim 1 wherein said preselected coefficient is a non-zero power of 2.