Abstract: An acoustic source for seismic exploration in a water environment consists of an elongated cylindrical housing, closed at both ends and containing laterally disposed exhaust ports. A reciprocable piston and piston follower are slidably mounted within the housing for reciprocal movement. Pressurized hydraulic fluid is admitted to one end of the housing, forcing the piston follower to contact the piston and move towards the opposite end of the housing. A pneumatic latching device retains the piston proximate opposite cylinder end and pressurizes the system. The hydraulic fluid is drained, allowing the piston follower to return to its original position. During the return trip of the piston follower, water is ingested through the exhaust ports to the chamber between the piston and the piston follower. A triggering mechanism then releases the piston that is accelerated towards the piston follower, to impulsively expel the contained water. The ejected water creates a momentary cavity in the surrounding water.

Abstract: The horizontal orientation of a rocket moving in a liquid is achieved by an arrangement in which a magnet is attached to the rocket body. The axis of the rocket and the magnetic axis of the magnet form an azimuthal angle .alpha., which determines the direction of the rocket relative to the geomagnetic meridian.

Abstract: The disclosed invention is a method of seismic exploration using non-impulsive vibratory sources activated by stationary, Gaussian codes in urban areas. The method adds a distortion-free quality to the full-waveform seismic records.

Abstract: A plurality of control station, watertight, submerged junction boxes are towed at spaced positions located along an airgun array, each junction box for including a microprocessor and data storage transmission capability, and airgun firing circuits to control predetermined airguns. The electrical cable for the array and the air supply lines, as well as the airguns to be controlled, are detachably coupled to respective junction boxes. Thus, the number of airguns in the towed array can be changed quickly and conveniently by coupling or uncoupling junction boxes and the associated airguns. A protective hose sheath extends between successive junction boxes and this hose sheath contains power lines and a communication bus, detachably connected to terminals in successive junction boxes. This hose sheath and interiors of junction boxes are pressurized with low pressure air during towing for excluding water in the event of a leak.

Abstract: A seismic detector comprises a casing the lower part (10) of which is provided with a plurality of apertures (19). A hydrophone transducer (70) comprising an annular ceramic member provided with metallized surfaces (71,72) is mounted in the casing and defines with the casing an enclosure (65) which houses a geophone (60). The outer face (71) of the hydrophone transducer (70) is subject to the ambient hydrostatic pressure via the apertures (19). The bottom of the casing is provided with a protuberance (11) to which a spike (12) is attached. The seismic detector can work in both hydrophonic and geophonic modes.

Abstract: A method and device for sensing hole parameters while drilling a borehole, and transmitting the sensed data to a remote receiver. Data are transmitted in digital format as a series of audible binary pulses generated by a solenoid acoustically coupled to the drill pipe. In a preferred embodiment, data transmission occurs automatically during periods of drilling inactivity.

Abstract: Seismic signals are processed to determine relative location error. In a further aspect, the relative location errors are corrected and the corrected seismic signals are processed to give information on subsurface structure.

Abstract: In an earth station (11), an amplifier (15) amplifies a pilot information signal with a variable gain. An up link pilot is thereby transmitted with a controllable transmission power. A beacon receiver (28) detects a level or C/N with which a beacon signal emitted by a satellite reaches the station. A pilot receiver (33) detects a level or C/N for a down link pilot radiated by the satellite in response to the up link pilot. A controller (37) controls the gain to keep a ratio between the levels or C/N's constant. For keeping a similar ratio constant, another station may transmit a transmission signal with a likewise controllable transmission power and receive the down link pilot together with a return signal radiated by the satellite in response to the transmission signal. Still another station may control a similarly controllable transmission power in consideration of an up link attenuation which is estimated from the level or C/N of the down link pilot.

Abstract: Range-dependent sensitivity of an RF doppler radar apparatus is reduced to prevent false alarms when small objects move in close proximity to the apparatus' antenna. The sensitivity is reduced by periodically FM-modulating the transmitted RF signal at a frequency corresponding to a wavelength which is at least four times the operating range of the apparatus. The reflection of the transmitted signal is mixed with the transmitted signal to produce a difference frequency signal which is sampled at instants of maximum amplitude.

Abstract: An improved well logging technique is provided for more accurately deriving and correlating a plurality of measurements made during a single traversal of a logging instrument through subsurface formations. In one exemplary embodiment, methods and apparatus are provided for deriving a more accurate and precise measurement of depth at which real-time logging measurements are made, and in particular for correcting anomalies occurring in the depth indication from cable stretch, yo-yo of the sonde in the borehole and the like. The more accurate and precise depth measurement is then utilized for generating well logging measurements on a depth-dependent basis, deriving at least some of such measurements in digital form and alternately transmitting to the surface digital and analog representations of such measurements.

Abstract: During the horizontal retrace scan period of a scanning beam in a television pickup tube, the beam current is increased to the maximum possible value to recharge the target layer, and the cathode voltage is raised by a few volts to prevent readout of normal video. Also, the scanning beam path may be modified to insure that every area of the image is scanned by the retrace scan prior to being scanned by the active picture scan.

Abstract: The invention provides a coil device having horizontal and vertical deflection coils around an outer surface of an image pickup tube to generate magnetic fields for deflecting electron beams in the horizontal and vertical directions, respectively. A correction coil is disposed between the outer surface of the image pickup tube and the horizontal deflection coil so as to correspond to the position of the vertical deflection coil. The number of turns of the correction coil is smaller than that of the vertical deflection coil. A signal for correcting scanning distortion of the electron beam caused by the deflection magnetic fields is supplied to the correction coil. The time constant of the correction coil is smaller than the period of the horizontal deflection signal. The correction coil is made of a printed circuit wiring.

Abstract: An apparatus and method for calibrating the output signal of a receiver having amplification over a predetermined input signal amplitude range has been described incorporating means for generating a sequence of reference signals each having a predetermined amplitude, means for coupling the sequence of reference signals to the input of the receiver, means for sensing the output reference signals of the receiver, means for storing output reference signals indicative of the amplitude along with corresponding input reference signals to provide a table of receiver input and output signals over the dynamic range such as 70 dB of the receiver. Unknown input signals are calibrated by looking up and comparing the amplitude of the output received signals of the receiver with stored output reference signals in the table and selecting the corresponding known input signals previously provided by the calibration signals.

Abstract: A external feedback network for decreasing variations in a beam pointing angle of a scanning antenna array. A dedicated aperture manifold is intergral with the aperture of the scanning antenna and provides a signal which represents the beam pointing angle. The signal is detected, decoded, and converted into digital data for averaging and processing by a CPU. The processed data is then compared with a value stored in memory and any difference forms the basis of a correction signal. For application to a microwave landing system, the correction signal is used to adjust the start/stop time of the scanning commands of the antenna to remove the error without modifying the beam steering algorithm. A space-coupled monitor may also be used independent of the feedback network to provide an alarm in response to any failure of the dedicated aperture manifold, the automatic stabilization circuitry or the array system.

Abstract: An information system for communicating information from each of a plurality of separate locations to each of a plurality of mobile objects includes a beacon at each location and a beacon triggering and detecting apparatus mounted on each object. Each beacon triggering and detecting apparatus is assigned a predetermined and unique time window within a common system cycle. During the initial portion of its window, the beacon triggering and detecting apparatus transmits a trigger signal at a frequency f.sub.1, with the trigger signal as transmitted having a substantially constant amplitude and with frequency f.sub.1 being chosen so that the intensity of the trigger signal decays as the cube of radial distance from the object. If the object is within a predetermined beacon trigger range of a location, the beacon at that location detects the trigger signal and transmits a beacon signal at a frequency f.sub.2 (substantially greater than frequency f.sub.

Abstract: A radar, lidar, or sonar system, comprising a transmitter and a receiver, the receiver including means for forming a plurality of contiguous receiver beams so as to define a predetermined angular sector of cover and means for narrowing each of the beams while contiguity is maintained between them, whereby the angular sector of cover is reduced for longer ranges.

Abstract: Disclosed is test apparatus included in a cable transmission system having intermediate local data units spaced along a cable, one connection to the cable also being to a master or control station. At each data unit, there is an input differential amplifier with two input terminals for application of at least one local data signal. A test signal is applied to the data unit via a transmission connection from the master station to a first element of a voltage divider connected to one of the two input terminals of the differential amplifier. A switch at the data unit is connected for disconnecting the data connection from the other input terminal of the differential amplifier. A second switch at the data unit, provides a connection to a conductor leading to the master station for connecting earth ground to the data unit local circuit common.