Abstract: A marine seismic data acquisition system and method includes a plurality of hydrophone arrays. A marine cable is towed in the water by a boat. The marine cable includes a plurality of active modules. Each active module is connected to a corresponding hydrophone array and collects seismic data from the geophones. The marine cable also includes a plurality of passive modules interspersed with a plurality of active modules, with each passive module generating, receiving and transmitting signals. The passive modules and the active modules are connected by electrical wires with each other and to the electronic equipment on the boat. The electronic equipment on the boat includes a subsystem for activating the active modules; another subsystem for interrogating the active modules and the passive modules and circuitry connected to the activating subsystem and to the interrogation subsystem which determines the source of transmission errors in signals received over the marine cable.

Abstract: The seismic amplifier includes an amplifying circuit which amplifies an analog signal to provide an amplified analog signal. The amplified analog signal is converted to digital signals. A controlled network connected to the amplifier circuit controls the gain of the amplifier circuit in a manner so that the gain for a current seismic operation, except for an initial seismic operation, is determined during the next previous vibration seismic operation.

Abstract: Apparatus for multiplexing ancillary devices in a streamer cable towed by a boat in ocean seismic operation, in which the cable includes a plurality of ancillary devices located throughout the cable. The apparatus includes a source providing step pulses located on the boat. Also located on the boat is a circuit providing control signals and a network providing control voltages. A plurality of series connected control pulse circuits are located in the streamer cable with the first control pulse circuit of the series being connected to the step pulse source. The control pulse circuits are responsive to the step pulses for providing a plurality of control pulses in a predetermined sequence. An energizing voltage source located on the boat provides a square wave energizing voltage. A plurality of switching networks are located throughout the cable with each switching network being connected to a corresponding ancillary device.

Abstract: A seismic type electrical multiconductor cable. It is made up with a predetermined length of cable, and has a number of geophone takeout connectors spaced along that length of cable. These takeouts are electrically connected to individual geophone circuits. Half go to pig-tail connected plugs at each end, and there are program circuits that may be plugged into the pig-tail plugs.By arranging the takeouts in pairs, physically on the same conductor but electrically isolated, only half the number of conductors are needed. There are additional conductors in the cable with multi-circuit connectors at each end. The cables are symmetrical and may be laid out end-to-end. A spread of cables would be made with connection to a recording station centrally of the spread.

Abstract: It has been found that by treating seismic data as damped oscillatory responses of earth layers in the form of resonating layer bars of rocks, data values, termed alpha values, can be obtained which yield an indication of subsurface composition. Seismic data are accordingly processed by obtaining an indication of the frequency-amplitude spectrum of each successive portion or data window of a seismic trace, determining the half-power points of each such spectrum for the trace, obtaining from the half-power points the alpha value for each trace and recording or plotting the alpha values. The alpha values obtained according to the present invention have been found to be useful in lithologic identification and in obtaining porosity information. The present invention is a calculator or digital data processing computer for obtaining such alpha values from field seismic data.