Abstract: Water inflow inside a seismic streamer may create parasitic electric connections between lines supplying current to the electronic devices of the streamer and lines transmitting seismic informations, thus damaging the electronic apparatus and making these informations inaccurate. In accordance with the invention streamer sections including sections of supply lines and transmission lines are provided with water inflow detection assemblies, each comprising a closed circuit element surrounding the supply lines, a conducting line connected to a DC voltage generator, and means for detecting any DC voltage therebetween resulting from parasitic connections between the supply lines and the closed circuit element, created by a water inflow.

Abstract: The method uses a combination monopulse and sequential lobing system to guide a vehicle, such as a missile, aircraft, auto, etc., toward a target. The target is tracked with conventional monopulse techniques while at the same time the vehicle is provided with coded data forming a cluster so as to provide spatial resolution information. The vehicle sequentially receives this information, stores the information until the sequence is complete and processes the information for guidance.

Abstract: A radar system testing apparatus for use in evaluating radar performance of terrain following, forward looking radars, generally installed in the nose of military aircraft. The operator inputs the antenna position and rotational arc limits desired which are converted into reference voltages and compared to the antenna's true position by a logic comparator network. When the true position is within the operator's selected window, and the radar system inputs a trigger signal to indicate transmitter firing, the logic network will respond with a spiked waveform. This waveform traverses two consecutive one shot multivibrators with appropriate controls to vary the width of the resultant output pulses. By controlling the size of the pulses, the operator effectively selects a variety of target ranges and target widths for testing purposes. These controlled pulses are fed back into the radar system where they generate a simulated target return for evaluating the performance of the radar system under known conditions.

Abstract: A seismic wave generator and method of using it, which comprises a vertical array of sources at known spacings, for detonation in a seismic wave propagating medium of known seismic velocity; means to initiate the sources in time sequence in a selected series of known different time intervals and recording the seismic waves at a distant location to provide a first electrical signal; and correlating the first electrical signal with a second electrical signal derived from the pattern of initiation, as modified by the travel times of the waves between the several separate charges.

Abstract: A cable system for carrying out seismic operations, comprising a multi-conductor cable built with multiple segments, each segment terminated with identical connector plugs. Each segment having a selected number P of take-outs for accepting P seismic signals. The group of P seismic signals from the take-outs are multiplexed in each cable segment, and travel over a single conductor pair in the successive segments to the recording truck, where they are demultiplexed, and as reconstituted signals, are processed and recorded.

Abstract: Acoustic signals are transmitted in a direction substantially perpendicular to the borehole axis, from different levels of at least three determined generatrices of the borehole wall. Reflected acoustic signals are received from the same direction at different levels of these generatrices. A train of signals is derived from each reflected acoustic signal and at least a group of significant elements of this signal train is selected. The groups of significant elements of the signals obtained for the different generatrices are correlated. The interval between signal trains corresponding to the maximum correlation corresponds to one and the same geological formation and is representative of the dip angle of this formation.

Abstract: Method and apparatus are provided for measuring acoustic signals having amplitudes of widely varying magnitude during one traversal of the borehole corresponding to indications of cement bonding along a casing as well as acoustic travel time through an increment of the formation. Variable attenuators are provided associated with acoustic receivers disposed within the logging sonde wherein attenuation may be automatically adjusted as a function of acoustic transmitter-receiver trigger pulses transmitted downhole, depending upon whether a cement bond or other log of acoustic signal information having a substantially different magnitude is desired.

Abstract: A helical antenna for radiating waves in both orthogonal states of circular olarization that is fed at the base by a first feed and at the tip by a second feed. The amplitude and phase of the signal from the first feed controls the amplitude and phase of the wave in the first orthogonal polarization while the amplitude and phase of the second signal from the second feed independently controls the amplitude and phase of the wave in the second polarization state. Radiated waves of any arbitrary polarization state are formed by adjusting the amplitude and phase of the feed signal. Alternative embodiments are disclosed and claimed.

Abstract: A beam position processor (15) generates address signals representing the spatial coordinates of points on a simulated radar beam, for a plurality of beam directions. The address signals serve for readout of weather information (e.g. cloud intensity, ceiling and base height data) from a data storage means (16) for further processing to form a video signal for display. The storage means (16) is arranged for economy of memory capacity in that the higher order parts of the address are used to read out code words from a database memory (17). Each code word selects one of a set of predetermined cloud patterns in cloud pattern memories (18, 19) and the lower order parts of the address access data corresponding to individual cells of the selected pattern.

Abstract: A carrier mounted seismic vibrator system that is primarily adapted for generation of high force, high frequency seismic energy into an earth medium. The apparatus includes first and second vibrators (12F and R) as supported by first and second lift systems (28F and R) disposed in tandem juxtaposition generally centrally in said vehicle (10), and the lift systems (28F and R) are designed to maintain equal hold-down force on the vibrator coupling baseplates (32F and R) without exceeding the weight of the carrier vehicle. The juxtaposed vibrators are then energized in synchronized relationship to propagate increased amounts of higher frequency seismic energy into an earth medium.

Abstract: An RF system is disclosed in which the input mixer of the system is also used as a switch to allow the local oscillator to be used as the transmitter oscillator. The switching mixer may also be used as an attenuator or signal modulator. A local oscillator is connected via a filter to a 90.degree. 3 db hybrid coupler. Two of the four ports of the hybrid coupler are coupled through impedance matching networks to reversely polarized mixer diodes. Bias circuits are connected to the mixer diodes for variably adjusting the bias current to the mixer diodes to thereby adjust their reflection/absorption characteristics. A second filter is connected between the first filter and the hybrid coupler for extracting an intermediate frequency signal. A third filter is connected to the fourth port of the hybrid coupler and to the antenna of the RF system. The first and third filters pass RF and local oscillator signals and block IF signals.

Abstract: A hydrophone cable having a series of hydrophones (7) at spaced intervals along the cable and having strength members (1) and transmission line conductors (3) extending along the cable in which a braided construction (2, 3, 4 and 5) is used which can be loosened to insert the hydrophones (7) into cable, voids in the cable being filled with a buoyant gel and the assembly covered by an outer plastic sheet (6).

Abstract: A radar system alternately transmits relatively short and long pulses. The video signals corresponding to the target returns from consecutive pulse transmissions are converted to digital format and then integrated except that radar return signals from targets within a first range resulting from long pulse transmissions are not used for integration.

Abstract: In a radar or sonar system wherein the detection of a target is to be accomplished with a constant false alarm rate (CFAR), a circuit is provided for adjusting the input to a comparator which compares the received echo signals against the value of a threshold in order to detect targets of interest. The mean value of the background noise is subtracted from the signal, and the resulting difference is divided by the square root of the variance of background noise. The use of the variance compensates for sweep-to-sweep correlation and non-stationarity (in the statistical sense) as is found in clutter so that the clutter, upon the customary sweep-to-sweep integration of the signal, does not tend to introduce a false echo.

Abstract: An impulse interference suppression circuit for use in combination with an -pulse Moving Target Indicator system comprising a gate connected to block the output signal from the MTI system when energized, and a circuit for taking the magnitudes of successive echo return signals, subtracting the magnitudes of consecutive echo signals to remove clutter, comparing the consecutive difference signals from such subtractions against each other, and generating and applying a blocking signal to the gate if the difference between the subtraction difference signals is above a given threshold level.

Abstract: A radar calibration apparatus for the metric measurement of ground position by airborne photogrametry using real time high precision imagery, the transformation of those measurements from camera coordinates to antenna coordinates, the conversion of transformed coordinates to direction cosines of a measured ground position, comparison to radar derived direction, and the calculation and automatic correction of bias errors in direction of the radar measurement.

Abstract: A Doppler radar speed sensing system includes a microwave transceiver and a circuit for generating an input pulse train having pulsewidths related to the ground speed of a vehicle carrying the system. A signal processor includes a microprocessor which executes a signal processing algorithm which converts the input pulse train to an output pulse train having desired characteristics. For example, the output pulse train has output pulses with pulsewidths and frequency related to the vehicle ground speed. The output signal pulse train responds rapidly to changes in sensed ground speed, but is insensitive to Doppler signal dropout.

Abstract: A method of reducing angle noise in return signals to a monopulse radar having a radome is shown to consist of the steps of: (a) transmitting a pair of signals at frequencies equally spaced above and below the tuning frequency of the radome; (b) digitally processing the return signals to form the complex monopulse ratios of the return signals corresponding to each one of the transmitted signals; (c) determining, by comparing the magnitudes of each monopulse sum and monopulse difference signals with the level of respective predetermined sum and difference reference signals, whether or not angle noise is exhibited and whether or not the signs of the imaginary parts of the monopulse difference signals differ; (d) comparing, to a threshold level, the amplitudes of the monopulse difference signals of those return signals which exhibit angle noise to select return signals exceeding such threshold level and whose signs differ; and, (e) averaging the real parts of the complex monopulse ratios of the return signals wh

Abstract: Pressure and velocity detectors produce outputs which are combined to substantially cancel ghost reflections. The pressure detector produces a positive output in response to upwardly travelling compressional waves and a negative output in response to downwardly travelling rarefaction waves. The velocity detector for this is a positive output in response to upwardly travelling compressional waves and a positive output in response to downwardly travelling rarefaction waves. These outputs are filtered so that the impulse response of the rarefaction waves cancels. The filtered outputs are combined to produce an output in which the ghost reflection is substantially suppressed.

Abstract: A method for marine seismic exploration, comprising the steps of first discharging simultaneously a set number of seismic sources having a known volume V.sub.1, resulting in several seismic waves with substantially identical form which after reflection by a same series of reflection points are detected by hydrophones as a sum signal of the individual emitted source waves having a frequency range f.sub.1. The sum signal is subsequently filtered by means of a suitable filter operation having a frequency range f.sub.1, resulting in a sum signal having substantially equal phase of the individual components in the frequency range f.sub.1, next discharging simultaneously a set number of seismic sources having a known volume V.sub.2, different from volume V.sub.1, resulting in several seismic waves with substantially identical form which after reflection are detected by hydrophones as a sum signal of the individual emitted source waves having a frequency range f.sub.2.