Abstract: A module is described for acquiring geophysical signals. The module includes at least one casing which is individually linked to one track. Each casing houses a processor which operates to digitize the geophysical signals. The module further includes two cable sections associated with each casing. Each cable section includes at a first end, a connector suitable for being coupled up to a complementary connector, and at a second end, an adapted configured to be fixed to a casing and to effect an electrical link with the processor housed in the casing.

Abstract: In an interferometric sensing apparatus, a scrambler is positioned in front of a polarizer, followed by a detector. In that way, although the two beams remain orthogonal to each other, they are continuously rotated, relative to the polarizer. In some positions, both beams pass through the polarizer and interfere, thus eliminating polarization fading. The signal is amplitude modulated at the rotation frequency of the scrambler, but this modulation is removed by low pass filtering.

Abstract: A marine cable includes chambers forming a necklace float. For filling, degassing the chambers and for connecting two successive chambers, the cable includes an intervention orifice between the chambers and with which the chambers communicate. Connection of the chambers to the intervention orifice is controlled by two valve mechanisms which each include an obturator spring-loaded against a communication opening and a guide rod which, when the obturator closes the opening, lies partly in the intervention orifice so that it is possible to push back the rods of the valve mechanisms from the intervention orifice for selective connection of the intervention orifice to one or the other of the two chambers or with both at the same time.

Abstract: A slave mobile plate accelerometer using variations of capacitance to detect the movement of a mass. The apparatus comprises at least one pair of fixed electrodes rigidly attached to an armature, and at least one mobile electrode suspended by springs from the armature, between the two fixed electrodes of each pair of fixed electrodes, to form two capacitors, each mobile electrode being adapted to move between the fixed electrodes of each pair of fixed electrodes, due to the effect of acceleration, so causing a variation of the capacitance of each capacitor. The accelerometer further includes an electronic circuit for adjusting the electrostatic stiffness of at least one combination of a fixed electrode and a mobile electrode and a control system for detecting the variation of the capacitance of each capacitor.

Abstract: A communication housing for devices external to a solid marine seismic cable, especially for level control devices, comprises an upper housing half and a lower housing half, coupled together around the cable. The upper housing half includes a plurality of wells, for example three wells, each adapted to receive a communication coil. The lower housing half has no such wells. The communication coils are wound in series to reinforce the signal strength of the communication signal. The communication coils are preferably formed to two segments, joined together at a flexible joint to reduce the likelihood of breakage of the coil core as the cable is wound onto a take up reel aboard the exploration vessel.

Abstract: The invention concerns an electrical connection device in particular for constituting geophysical data acquisition and processing systems, consisting of two identical electrically and mechanically fitting male/female connectors, each connector comprising a body (10) bearing a set of connection pins and a ring (20) enclosing the connector body base and capable of being moved in rotation relatively to said body, the connector ring comprising an raised motif (27) for plugging in the associated connector. The invention is characterized in that the body of each connector comprises two stages of raised motif of which one front raised stage substantially matching the ring motif to co-operate with the associated connector ring motif in a locked position of the device and a rear stage to co-operate with the ring motif of the same connector in a retracted position of said ring.

Abstract: Seismic acquisition apparatus comprising a plurality of detectors (s1, s2, etc.) each constituted by one or more seismic sensors, combiner means which generate at least one seismic trace corresponding to a group of detectors by combining the signals output thereby, and memory means for storing the seismic traces generated in this way, the apparatus being characterized in that it includes seismic preprocessor means (&mgr;P1, &mgr;P2, etc.) for re-phasing the signals output by the detectors prior to the signals being combined and/or prior to accidental noise on said signals being eliminated.

Abstract: A method of and an apparatus for mounting seismic vibration sensors to a cable designed for use offshore, such that the sensors are optimally coupled to the ocean floor through all cylindrical rotations when the cable has reached the bottom after being slipped over the transom of a deployment vessel. Said coupling is accomplished without the use of a sub-surface robotic vessel to force the sensors into a particular orientation. The housing for the sensors is adapted to endure and minimize the impact on the host cable of the mechanical extremes the system is subjected to in the process of the conventional deployment and retrieval methods.

Abstract: The present invention provides a track-type carriage system for heavy vehicles, and, in the preferred embodiment, a track-type carriage system for an articulated steering seismic vibrator vehicle. The carriage system consists of four track modules, two fore and two aft, each independently mounted at one end of a heavy axle and bearing a proportionate share of the vehicle weight as applied to the track module via a ground pressure cylinder. Each track module includes an S-shaped frame interrelating a large drive wheel mounted to the axle, a pair of forwardly mounted idler wheels and a plurality of mid-wheels. A stabilizing mechanism manages torsional and lateral forces and also accommodates for fore and aft movement of the track module frame.

Abstract: In the proposed method of radio satellite localization of points on the surface of the earth:a pseudolite transmitter (1) is placed on a masked point (P);the antenna (3) of radio localization means (2) is placed successively in a plurality of arbitrary points (P.sub.i) where reception of the signals transmitted by the satellite is satisfactory, and the phase of the signal transmitted by the pseudolite transmitter (1) and received by the antenna at said points is measured; andthe coordinates of the masked point (P) is determined as a function of said measurements and as a function of the coordinates of the points (P.sub.i).The apparatus includes a pseudolite transmitter (1) and a radio localization mobile receiver (2) having one of its channels allocated to receiving the signal (S.sub.p) transmitted by the pseudolite transmitter (1).

Abstract: A method of staking out a point on the ground using a satellite positioning system comprises the following steps: two reference points near a target point are marked on the ground and the positioning system antenna is located on each of the two points to determine their coordinates, the position of the target point relative to the two reference points is determined from these coordinates, the point corresponding to this relative position is marked on the ground, and the staking out is done at this point. The device for implementing the method includes arrangements for marking the two reference points and the target point on the ground.

Abstract: An atomic clock of the type comprising a quartz oscillator, a tube contaig a material, the atoms of which have an hyperfine spectral transition, control means capable of generating, from the quartz oscillator, a control signal of a frequency that corresponds to the hyperfine spectral transition, and of applying this control signal to the tube to cause interaction between this signal and the atoms of the material contained in the tube, and feedback means that are sensitive to the response of the tube and are adapted to modifying the frequency of the quartz oscillator so as to substantially center the frequency of the control signal on the frequency of the hyperfine spectral transition, wherein the control means are adapted to cyclically generate test signals, the controlled frequency of which is located outside the Ramsey peak.

Abstract: The encoder comprises a pendulum (P) mounted to rotate about a horizontal is (O-O) which is substantially coaxial with a reference axis (R-R) of an index disk and which carries vertical optical detector equipment (T.sub.M.pi.E, T.sub.M.pi.R, T.sub.MOE, T.sub.MOR), optical guidance means (M.sub.1, M.sub.2, M.sub.3, M.sub.4, T.sub.5) fixed to the pendulum and suitable for guiding radiation generated by an optical transmitter (T.sub.M.pi.E) towards an associated optical receiver (T.sub.M.pi.R) along a predetermined optical path intersecting the disk (D), and a liquid level forming device (L) fixed to the pendulum (P) and inserted on the optical path upstream from the said point of interception between the optical path and the disk, the said optical guidance means (M.sub.1, M.sub.2, M.sub.3, M.sub.4, M.sub.

Abstract: The present invention relates to a telemeter and to a method of determining the distance separating two points. The method comprises the steps consisting in (a) comparing the phase (.phi.) of the modulation of an emission signal and of a received returned modulated signal (16), (b) in generating a signal representative of the value of the instantaneous variance (V(.phi..sub.i)) of the phase samples (.phi..sub.i) (107), (c) in generating an estimation of the phase on the basis of a signal derived from the average (.phi..sub.E) of n phase samples (.phi..sub.i) which have been weighted by their instantaneous variance, (d) in generating a signal representative of the value of the distance (D) on the basis of the estimated phase value (.phi..sub.E), and (e) in displaying said value of the distance.

Abstract: The invention relates to the radio-electrical transmission of accurate timing-mark signals. A space-diversity electrical connection is formed between a station having one single antenna and a station having two antennae and one of the stations is equipped with a receiver device which combines into one composite timing-mark signal the different repetitive timing-marks decoded and rectified from high-frequency signals which have traversed several spatial propagation paths. A common automatic gain control circuit weights the decoded and rectified timing marks according to a weighting which diminishes with the level of high frequency reception. Preferably the rectification of the timing marks is carried out non-linearly.

Abstract: Measurement of distance is carried out by transmitting a VHF wave train crising a sinusoidal signal modulated by phase inversion in accordance with a pseudo-random sequence, at a receiver shifting a like second sequence until it coincides with the received sequence, re-transmitting a signal modulated by the second sequence, receiving the second sequence and shifting a like third sequence until it coincides with the received second sequence, and measuring the phase shift between the third sequence and a like reference sequence.

Abstract: An electronic angular coder for theodolites or the like, comprising a rotng disk bearing a series of engraved radial markings, a stationary detector, and a mobile detector. An approximate measure of the offset angle between a stationary detector and a mobile detector is accomplished by counting the markings passing in front of the heads. Fine measures of the shift in phase between the passage of a marking in front of the mobile detector and the fixed detector are also obtained.

Abstract: Apparatus for obtaining seismic data or information in the field comprises electrical communication paths established between seismic detectors distributed over the ground, and a digital seismic data recorder. Each of the paths comprises a pre-amplifier, various filters, a regulable-gain amplifier, and finally a digitizer, or the paths have these elements at least partly in common. The digitizer operates by carrying out random weighing; it comprises a pseudo-random generator and at least part of the contents of this generator is loaded in parallel into a register. The pseudo-random number thus obtained is converted into an analogue signal and is used for weighing a sample of the seismic signal in a comparator. This gives a single bit each time, which is then recorded in the recorder.

Abstract: In a digital angle coder, a revolving disc bears a first series of marks ularly spaced around its axis, capable of being read by two diametrically-opposed fixed heads, and a second series of marks equal in number to the first, regularly spaced around the axis and capable of being read by two diametrically opposed movable heads. Each of the heads includes, for example, a grid reproducing a portion of the series of marks, a photo-emission element and a photo-receiving element. A first auxiliary mark may be read by a fixed auxiliary head and a second auxiliary mark may be read by a movable auxiliary head.

Abstract: The invention relates to an electromagnetic velocity pickup of the horizol seismometer type, wherein an oscillating mass is elastically suspended as an inverted pendulum with the aid of a deformable system of the articulated parallelogram type. The pickup is characterized in that the suspension comprises rigid beams and at least one elastic pivot.