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: Radar display apparatus employs digital techniques to convert range/azimuth scan to T.V. scan. A digital store contains data defining the brightness of levels for the picture cells of a T.V. display. The store is continuously updated in accordance with received video from a digitiser. The correct cell in the store for updating is identified by converting polar coordinates to Cartesian coordinates in a Sin .theta., Cos .theta. generator and integrators. The contents of the store for the addressed picture cell is modified by a control unit in accordance with the digitised video return so as to represent the degree of positive correlation of returns in that cell on successive azimuth scans of the radar. Thus the brightness or color of the cell on the T.V. display represents this degree of correlation.

Abstract: A method of and an apparatus for generating and transmitting wideband, exded radar pulses which spatially decorrelate clutter and are frequency-hopped from pulse to pulse by the proper frequency difference for clutter decorrelation by frequency-diversity are disclosed. The returned signals are compressed, delayed by one pulse interval and correlated, each with its succeeding echo pulse, to decorrelate the clutter returns but not the target echoes. The frequencies of the transmitted pulses are locked to the local oscillator frequency which is very stable. A double-sideband technique is used to generate the different pulse frequencies.

Abstract: A ferroresonant power supply having a relatively temperature stable output voltage includes a saturating magnetic element having a magnetizable core and a winding located thereon. A magnetizing current is developed in the winding by a high frequency source of alternating input voltage for generating an alternating magnetic flux in the magnetizable core that links the winding so as to develop an alternating polarity output voltage. A capacitor develops a circulating current that generates a magnetic flux in a core section associated with the winding that aids in magnetically saturating the core section to provide regulation of the alternating polarity output voltage by means of ferroresonant action. In order to temperature stabilize the output voltage, the magnetically saturating core section of the magnetic element is formed of a ferrospinel comprising a lithium ferrite or a substituted lithium ferrite.

Abstract: Inflight training apparatus is provided for military aircraft radar warning receivers that is plug compatible with the standard receiver processor to provide realistic training scenarios responsive to pilot maneuvering while recording the pilot's actions for post flight analysis. The training apparatus includes inertial navigation equipment to indicate position and attitude of the training aircraft, a memory in which is stored position and types of enemy radars and threats that would be encountered on an actual combat mission, and a processor which receives inputs from the inertial navigation equipment, memory and radar warning receiver control panel to control the standard receiver video display to generate the training scenario thereon. The training display moves, rotates, and is blanked simulating the effects of aircraft altitude and attitude as the aircraft turns, banks and performs other maneuvers which may be navigational or evasive maneuvers.

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: 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: 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 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 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 power supply circuit is provided with a voltage control circuit (1) with negative feedback for applying a rapidly changing high voltage to the anode of a penetron-type cathode ray tube (3) for a color display system and with a deflection voltage correcting unit (5) for obtaining color-independent pictures on the screen of the cathode ray tube. The deflection voltage correcting unit is controlled by at least a correction signal derived from an input voltage of the voltage control circuit.

Abstract: A double sideband linear frequency modulation technique for radar applications is disclosed for obtaining simultaneous range and doppler measurements. The method of obtaining measurements is useful in a variety of radar applications; however, the most promising area is in continuous wave radar systems. Linear Frequency Modulated (LFM) waveforms of both increasing and decreasing frequency are simultaneously transmitted. Upon reception, these sideband signals are combined coherently to give an output that is a function of the target's radial velocity. The received signals are also processed separately to obtain target ranging information.