Abstract: Digital simulation apparatus, e.g. a digital coastline generator, for simulating a terrain-representative display of the kind produced by a movable scanning-type display device, e.g. a radar display device, comprises a main store for storing digital data representative, in Cartesian co-ordinate form, of terrain features such as contours and buildings in an area, known as the playing area, typically 256 nautical miles by 256 nautical miles. The data is divided into groups relating to contiguous zones each typically 2 nautical miles by 2 nautical miles. The apparatus further comprises means for producing a signal representative of the current position of the display device in the playing area, means for producing successive signals representative of successive segments of scan of the display device, and means responsive to these signals to select from the main store those groups of data corresponding to zones intersected by the current scan segment.

Abstract: An improved portable seismic energy source including a base member having cylindrical sidewalls and an open lower end for resting on the earth's surface, a horizontal baseplate secured to the base member upper end, the baseplate having a central opening therein, a gun mounted on the horizontal baseplate for firing a projectile through the opening therein to impact the earth's surface and generate a seismic signal, a spatter plate mounted to the base member such as by means of a vertical cylinder secured to the lower surface of the baseplate with the lower end of the cylinder being affixed to the spatter plate, the spatter plate having an opening therein in register with the cylinder so that a projectile fired passes through the opening, the spatter plate being positioned above the earth's surface, and a flexible diaphragm secured at its periphery to the lower circumferential surface of the base member and having a central opening therein, the diaphragm being stretched over the top of the spatter plate, the sp

Abstract: Located adjacent to runways, taxiways, and approach ramps are secondary radar interrogators which radiate the P1 and P3 pulses and the P2 pulse via different directional patterns into sectors to be monitored which are individually assigned to each interrogator. Direction finders at different locations determine the directions of arrival of SSR reply signals radiated by an airborne SSR transponder in a sector to be monitored. From the directions of arrival and the locations of the direction finders, the respective transponder position is determined. The interrogators require no central control. Alternatively, the arrival times of the SSR reply signals are measured at several points; an evaluating device forms the differences in arrival time, and the intersection of the hyperbolic lines of position determined in the evaluating device is the position of the transponder.

Abstract: In a monopulse radar, a system is included to adaptively assess a detected threat in accordance with the relative bearing representative measurements thereof to determine the collision potential of the threat with the radar. The monopulse radar is operative to detect at least one potential threat and to track the threat through a sequence of time increments beginning with the detection thereof. For each time increment, a signal representative of the relative bearing of the detected threat is derived, forming a sequence of relative bearing representative signals respectively corresponding to the sequence of time increments.

Abstract: A device for monitoring a Doppler VOR system emitting sinusoidal signals at a frequency of 30 Hz, one called "reference" and the other called "variable" whose phase varies with respect to that of the first signal, comprises at least one sensor close to the Doppler VOR system, a first processing device supplying the information emitted by the VOR system in the direction of the sensor and a second device for processing the signal received by the central antenna, said devices comprising means for separating the two upper and lower side-bands of the VHF carrier wave.

Abstract: An apparatus for and a method of determining the material properties of a dielectric and/or conducting radar target by deciphering the backscattered signals returned from the target is disclosed. The resonance "code" of the echo signals from the target is a function of the width and spacing of the resonant spectral lines in the transverse electric (TE) and transverse magnetic (TM) modes of the returned signals. The resonances present in any TE or TM mode become uniformly spaced and of uniform width at high frequencies. The uniform spacing between adjacent resonances is used to uniquely determine the dielectric constant of the material comprising the target, and their uniform width is used to uniquely determine its thickness.

Abstract: A monitor located about 100 m from the ILS localizer determines whether the DDM alarm threshold was exceeded due to an equipment error or to an error caused by an overflying aircraft. To accomplish this, either the maximum of the frequency spectrum of the variation with time of the differentiated DDM signal is located, or the frequency spectrum of the variation with time of the DDM signal or of the differentiated DDM signal is compared with one or a plurality of spectra typical of equipment errors or of errors caused by overflying aircraft.

Abstract: Two STC configurations for precision control of RF attenuators, each configuration utilizing a log-scale electronic attenuator, are disclosed. The first configuration includes a D/A converter/linear-to-log module combination to provide a log range ramp; the second configuration utilizes a log table ROM/D-A converter to provide a precision log range ramp, the range so generated controlling the log-scale electronic attenuator utilized in the radio frequency receiver.

Abstract: A vehicle velocity sensing system is disclosed which includes a doppler velocity sensor (10, 12) and means for reducing spurious signal components in the output of the sensor. An accelerometer (30, 32) is mounted so as to sense vehicle accelerations along the boresight of the doppler velocity sensor. A processor (34, 36) processes the output of the accelerometer to provide a signal which corresponds essentially to the spurious components of the output of the doppler radar velocity sensor. A signal combiner (38, 40) combines the output of the processor with the output of the doppler velocity sensor to derive a corrected output signal which is more closely indicative of the velocity of the vehicle.

Abstract: A digital scan converter is provided with a memory, each cell of which contains brightness data for presenting a corresponding video signals on a raster scan display at positions corresponding with the respective cells; a logical unit for supplying, in response to the applied video signals and the brightness data stored in memory, new brightness data overwriting that stored in memory; an address conversion circuit for converting the addresses established in polar coordinates into addresses expressed in Cartesian coordinates to store the new brightness data in memory; and with a circuit connected to the memory for reading out the brightness data and for presenting corresponding video signals on the raster scan display.

Abstract: A miniature handheld receiver contained in a metal shielding enclosure incorporating a slot type directional antenna as a part of the structure such that when the antenna is aligned with a radio frequency signal of interest, a null is produced in the signal level. The antenna is coupled to receiver circuitry which includes an oscillator used to FM modulate the signal by tone injection when an unmodulated carrier is present, an FM detector for demodulating the RF signal, an audio amplifier for amplifying the demodulated audio and an acoustically coupled earphone to prevent stray RF pickup from the earphone cord.

Abstract: A gas gun assembly for measuring depths of reflectors in a well bore includes a housing having a central chamber and bottom bulkhead through which a first valve bore extends. Coupling structure is provided to connect the housing to the well. A cap closure for the chamber has a second valve bore therethrough of diameter larger than the diameter of the first valve bore and is located in axial alignment with the first valve bore. A valve stem has one end axially movable within the second valve bore while closing the same and the other end movable into and out of the first valve bore. A predetermined pressure condition is established across the bulkhead. The valve stem is then released for rapid equalization of pressure across the bulkhead to produce an acoustic pulse in the well bore.

Abstract: A directive antenna feed arrangement providing for multiple selectable beam locations and with the ability to provide multiple and independently locatable nulls in specific angular directions in the sidelobe structure of the radiation pattern. An antenna having a plurality of independent antenna elements linearly deployed is coupled to a beam-forming network such as a Rotman lens feed. Main beam directivity is controlled by selection of the Rotman lens ports corresponding to the desired beam direction. Other angles corresponding to the directions of unwanted signals, especially those received on the major sidelobes, are effectively nulled by a phasing network discretely connected to the Rotman lens port at the appropriate angle, the phase control receive signals being mixed with the main beam signal energy. Angle tracking and beam-steering circuits are depicted and described for control of the main beam angle and positioning of the nulls generated.

Abstract: A lightweight rigid housing and baseplate structure for a seismic transducer. The baseplate (12) includes a central hub (26) for receiving a lower piston rod (76). Upper and lower skin plates (32 and 36) extend radially outward from the central hub (26). A plurality of equally angularly spaced reinforcing plates (40) also extend radially outward from the hub (26) and have their upper and lower edges rigidly connected to the upper and lower skin plates. A housing assembly (78) rigidly connects an upper piston rod (74) to the baseplate (12), and includes a frusto-conical section (82). The lightweight rigid housing (78) and baseplate (12) structure provides a seismic transducer having in-phase force distribution over substantially the entire area of the baseplate as it is engaged with the earth.

Abstract: An improved method for three-dimensional seismic exploration of the subterranean structure of the earth is disclosed wherein arrays of sources of acoustic energy and of detectors of reflected energy are used. The configurations of both arrays are conjointly experimented with to improve the signal-to-noise ratio of the resultant data; the signals output by the detectors are summed, and are correlated with those output with respect to all acoustic energy emitted within a given array of sources.

Abstract: A cathode ray tube socket, including a thick film ceramic plate mounted thereon and forming electronic control circuitry in association with the socket structure.

Abstract: A Doppler radar is adapted to respond only to walking human targets by prding means to detect the frequency modulation of the Doppler signals caused by the oscillatory body movements of such walking targets. A frequency locked loop frequency modulation detector is provided for efficient detection of this so-called step frequency modulation, and the detected step frequencies are split into several bands representing targets walking at different step rates. Circuitry is shown for adapting this technique to continuous wave radars or range gated radars.

Abstract: A method and apparatus for gathering a geophone sensor string (10) is provided. The geophone sensor string (10) comprises individual sensors (12) for sensing motion of the earth, an interconnecting cable (14) and ring members (22). A line (30) is secured to a ring member (22) at one end of the geophone sensor string. The line is passed through the remaining ring members on the geophone sensor string and extends through the ring member adjacent the opposite end of the geophone sensor string. Drawing the line (30) in the direction of the arrow (32) lifts the sensors off the ground and gathers the sensors and interconnecting cable in an untangled and compact form for storage. The technique of the present invention is adapted for use with vehicles to eliminate manual labor.

Abstract: A seismic exploration method is disclosed for filtering the signals produced by a detector placed at different depths in a well in response to an emission of acoustic waves from a source on the surface: the signals comprising downgoing wave components and upgoing wave components.The filtering consists in sampling from among the N signals to be processed a group of n signals s.sub.l . . . s.sub.n detected at respective levels x.sub.l . . . x.sub.n, in determining the propagation time t.sub.k of the acoustic waves from the level x.sub.l to each level x.sub.k, in advancing the signals s.sub.k by the time t.sub.k in relation to s.sub.l and in adding s.sub.l and the signals s.sub.k thus shifted to obtain a sum z.sub.l, in calculating a sum y.sub.l of s.sub.l and of the signals s.sub.k delayed by the time t.sub.k in relation to s.sub.l, in generating a signal u.sub.l *, defined as an optimum estimation of the upgoing wave component, from the sums y.sub.l and z.sub.

Abstract: A monopulse radar comprising a pilot signal generator (20) for injecting phase and amplitude-defined pilot signals into the separate receiving channels (6-12, 3, 16-19) to obtain correction signals through the variation in the mutual phase and amplitude relationship between the separate receiving channels for correcting angle error signals derived from target return signals. The pilot signal generator (20) and the transmitter (1) are tunable and a control circuit is incorporated for adapting the pilot signal generator (20) relative to the frequency of the target return signals.