Abstract: A method for improving signal-to-noise ratio in seismic surveying. It involves generating a series of seismic charges at time spaced intervals but at the same location. A single record is made having a time duration sufficient to cover the maximum reflection time of interest plus the total time for the series of charges. And, thereafter, the record is processed by Fourier transform of the single record to the frequency domain and by constructing frequency domain representation of the series of time intervals plus using the latter to superimpose frequency domain representations of the seismic signals resulting from each of the seismic charges. Then the processing includes inversely transforming the superimposed frequency domain representations back to the time domain.

Abstract: A method for preventing a radar beacon's response to received pulses from a vessel which originate from the side lobes of the vessel antenna. The carrier frequency of the radar signal pulses to and received by the beacon is measured and a value of this frequency is stored when the amplitudes of the signal pulses exceed a certain high threshold level (Th). If signals after that are received which exceed a low threshold level (Tl) (but not the high) the carrier frequency of such signals is measured and a corresponding value is stored. Measuring two subsequent and equal carrier frequencies is considered as a criterion that a response signal from the beacon responding to the second received signal should not be transmitted. An arrangement to carry out the method is described.

Abstract: In seismic exploration a seismic source transmits seismic energy into the earth and seismic detectors record the seismic waves returning to the earth's surface from reflecting subsurface interfaces. The downgoing transmitted seismic energy and the upcoming reflected seismic waves are transformed into the frequency domain, downward continued, and summed to produce a migrated seismic depth section.

Abstract: Cathode ray tube drive circuitry in which non-linearity of the line scan is corrected by varying the frequency of the pel clock oscillator in accordance with anticipated variations in scanning speed. Predetermined speed corrections are stored in a digital store 23 and, by means of digital to analog converter 24 and integrator 25, are applied to the control input of a voltage controlled oscillator 13. Synchronization of the pel clock with the X-deflection waveform is effected by means of a parallel phase-locked loop comprising counter 15, sample and hold 18, amplifier 20 and low pass filter 21. Preferably a sinusoidal waveform is applied to the X-deflection coil in such a manner as to have a bidirectional raster scan, the X-deflection coil forming part of a tuned circuit of the sinusoidal waveform generator.

Abstract: A solid propellant gas generator operating with a calibrated tunable resonator produces a strong sonic field capable of affecting particle coagulation in an aerosol. The resonator is calibrated to produce a sonic field at the optimum frequency for a given aerosol and can be changed according to the aerosol involved. The resultant coagulation increases visibility and/or electromagnetic transmissibility within the sonic field. The device can be used to reduce obscuration during battlefield operations.

Abstract: An apparatus for control of ground clutter breakthrough in MTI radar which remove hard limited clutter signals while allowing increased detection sensitivity to moving targets when such strong clutter returns are not present. Logic is provided to prevent the removal of strong moving target return even in the presence of hard limited clutter.

Abstract: Process for real time signal processing for side-looking synthetic aperture radar systems, the signal consisting of sample sequences corresponding to given spacing gates. For each spacing gate an operation corresponding to an auto-correlation is directly performed on the radar signal, this relating to a product signal of a sample by a phase term varying quadratically with the rank of the sample, which supplies an estimate of the Fourier components of the radar image for each gate.The invention also relates to a circuit for processing the radar signal in real time for performing the aforementioned process.

Abstract: A geophone is disclosed which includes at least two transducers having axes which are perpendicular to each other for sensing vertical and horizontal in-line components of seismic waves. In one arrangement, the geophone includes a signal processor which includes active circuit elements responsive to the transducer output for suppressing ground roll components included in the transducer outputs. At least one of transducer output signals with ground roll signal components suppressed therefrom is connected to a remote location for recording. When more than one signal is to be sent from the geophone to the remote recording location, a mulliplexer is provided at the geophone for transmission of a plurality of geophone output signals to the remote location over a single transmission path, such as a dual-conductor transmission line. Analog and digital versions of the geophone are disclosed.

Abstract: A method of seismic prospecting is disclosed in which the seismic source is excited in such a manner as to maximize the use of the energy generated by the seismic source. In certain cases it may be desirable to convert the received seismic signals to their frequency domain counterparts before performing subsequent processing. Such conversion may be performed using the discrete Fourier transform with the result that transformed values are obtained only at certain discrete frequencies. It may further be desirable that processing be performed only at subsets of the total set of discrete frequencies with the values at the remaining frequencies being discarded. In the practice of the present invention, source energy is generated only at those discrete frequencies at which subsequent processing is to be performed. As a result there is substantially no source energy in the transform values at the frequencies which are discarded.

Abstract: The length and width of fissures in a bore hole is determined by alternately flowing liquid into and out of the formation from an isolated zone of a bore hole, at different frequencies, and measuring the dynamic pressure of the flowing fluid. The length of fissures in the isolated zone is determined from frequency peaks at high pressure to flow ratios, and the thickness of the fissures is determined from variations of pressure-flow ratios with frequency by comparison with known data. Sonde apparatus for practicing the method is also disclosed.

Abstract: An improved well logging system and method is provided for deriving and visibly displaying a recordable representation of a comprehensive lithological profile of the earth materials traversed by a borehole. In a particular form of the invention, all logging measurements are derived in digital form and on the same depth-dependent bases, such that measurements taken during one trip through the borehole may be combined or processed with other logging measurements taken during a different trip through the same borehole of interest, such that all of the measurements may then be processed at one time to derive the various lithological indications sought to be provided.An improved monitoring system and technique is further provided, such that those logging measurements and lithological relationships of interest may also be correlatively displayed on a real-time basis with respect to at least some of the logging measurements from which they are derived.

Abstract: A distance measuring system in which a first station (FIG. 1) radiates a modulated carrier wave and a second station (FIG. 2) receives that wave, and retransmits the modulation on a carrier wave back to the first station, which compares the phases of the original and received modulations. The second station includes a digital counter (19) which accumulates clock pulses denoting the period of the modulation and a second counter is incremented and decremented to reproduce the modulation for retransmission thereof.

Abstract: A dual mode vibrator (DMV), in its hydraulic cylinder, automatically provides a shorter stroke for higher frequencies and a longer stroke for lower frequencies. The cylinder contains a pair of sleeves, each sleeve having one diameter portion sufficient to slideably engage the piston and having a smaller diameter portion to slideably engage the piston rod. The sleeves themselves are moveable within the cylinder, such movement being effected by the application of high pressure on one end or the other. When the sleeves are moved together, the stroke is effectively shortened. When the sleeves are moved apart, the stroke is effectively lengthened.

Abstract: A medium to low PRF pulse doppler radar wherein the effect of the clutter notch filter is eliminated at times when the doppler frequency of the target approximates the doppler frequency of the clutter to continue tracking the target provided that the doppler frequency of the target and clutter are at different ranges.

Abstract: An apparatus is disclosed by which radar targets can be imaged in two dimions for identification at full radar range using relatively moderate speed data processing. Images of targets are found in range and cross-range dimensions from the time history of the targets' wideband spectral response obtained by a frequency stepping radar. A frequency synthesizer generates a series of N identical signal bursts, each burst comprising n pulses and each of said n pulses being a different frequency. The radar echos from this series of bursts is separated into n-phase and quadrature phase components. These components are processed to calculate and store the relative amplitude of each echo signal and to determine the phase of each echo signal relative to the phase of the corresponding transmitted pulse. Further, the echo signals are inverse Fourier Transformed to generate an n.times.N Fourier Transform array representing a synthetic target range profile.

Abstract: A pulse width and amplitude control apparatus wherein an analog Doppler to digital pulse converter provides pulses to the up input of an up/down counter in the presence of a noise input or a Doppler input, and a second analog Doppler to digital pulse converter applies pulses with greater frequency to the down input of the up/down counter when a Doppler signal exceeding a predetermined threshold is present, so that a low or no signal condition increases and a high signal condition decreases the transmit pulse envelope.

Abstract: A synthetic aperture radar (SAR) target simulator for simulating the radar return, or echo, from a target seen by a SAR antenna mounted on a platform moving with respect to the target includes a first-in first-out memory (26) which has digital information clocked in at a rate related to the frequency of a transmitted radar signal and digital information clocked out with a fixed delay defining range between the SAR and the simulated target, and at a rate related to the frequency of the return signal. An rf input signal having a frequency similar to that utilized by a synthetic aperture array radar is mixed with a local oscillator (16) signal to provide a first baseband signal having a frequency considerably lower than that of the rf input signal. The first baseband signal is converted to a plurality of digital words which are clocked into the memory (26) at a rate related to the frequency of the local oscillator (16).

Abstract: A marine seismic cable is sectionalized with the individual cable sections being joined by articulated connector assemblies which permit relative bending movement between such individual cable sections.

Abstract: A well logging method and apparatus for detecting the first arrival of an acoustic wave in a logging signal under adverse signal conditions. The received acoustic signal is amplified at a fixed gain until clipped at the largest amplitude throughout the logging procedure. This amplified signal is converted RMS to DC level signal and stored in sample and hold means for a period shortly before first arrival of the acoustic wave. The continuing DC level signal and the stored DC level signal are compared to produce a comparator output DC signal when the continuing DC signal has a certain increased magnitude. This certain increased magnitude is used to generate a pulse of given magnitude and duration that is especially suitable in digital data systems.

Abstract: An acoustic positioning system locates a marine cable at an exploration site, such cable employing a plurality of hydrophones at spaced-apart positions along the cable. A marine vessel measures water depth to the cable as the vessel passes over the cable and interrogates the hydrophones with sonar pulses along a slant range as the vessel travels in a parallel and horizontally offset path to the cable. The location of the hydrophones is determined from the recordings of water depth and slant range.