Abstract: A method is disclosed to provide optimal or near-optimal vertical stacking of seismic records within the constraints imposed by real time data acquisition procedures. This method is characterized by forming output seismic traces which are a sum of prorated input traces, such proration being performed by application of smoothly varying weight functions derived from estimated signal and noise power levels within each input trace. Each weight function is computed using frequency domain filtering techniques to obtain a well behaved bandlimited time series for each function. The method also includes a procedure for clipping grossly large noise spikes in the input traces before the stacking procedure is performed, thereby guarding the weight calculation procedure against aliasing effects induced by such spikes.

Abstract: Method and apparatus for digitally deriving arrays from seismic data. Indentical parallel processing elements connected between common input/output buses are each preselected to derive different pluralities of arrays. Array specifications defining the arrays are downloaded into the processing elements. A scan sample set of spatially distributed seismic receivers is periodically generated and placed on the input bus. Each processing element, in response to array specifications, captures and stores all receiver output signals in the scan required to derive its respective arrays, derives its assigned arrays, and delivers resultant array samples to the output bus. Double input and output buffering in the processing elements is provided whereby receiver capture, array derivation, and outputing processes occur simultaneously in each processing element.

Abstract: Disclosed herein is circuitry for producing a signal proportional to the rate of recurrence of a periodic input signal applied to the circuitry. When an input pulse is received a timing circuit is energized to charge a capacitor to a predetermined level. The capacitor is then discharged through a resistance circuit having resistance portions which are electronically switched in and out of the circuit so that the discharge, rate of the capacitor defines the desired rate function. Then, upon commencement of a subsequent pulse a sample and hold circuit is actuated to sample the discharge level of the capacitor to provide an accurate indication of the pulse rate.