Abstract: An aircraft-launched, ram-air inflatable, passive radar decoy (10) has a substantially cylindrically shaped body (12) having an open forward end (14) and a closed porous rearward end (16), the body comprised of a fabric reinforced composite having a high radar reflectivity coating on at least it interior surfaces (12i, 16i). A rod-shaped weight (22) is attached at the forward end (14) by way of shroud lines (20), the weight (22) providing the highest weight-to-drag-area ratio for the particular size body. The decoy (10) provides a high radar cross section and broad angle coverage to ground-based source of radar when it is ram-air inflated upon ejection by the aircraft into its adjacent windstream.

Abstract: In accordance with a first arrangement, a non-coherent, pulse radar transmitter emits N-sequential signals of differing frequencies at predetermined time intervals, the transmitted pulses being directed toward a given target area of interest. Further included is a radar receiver for detecting and processing the composite radar return signal samples of N differing frequencies which are reflected from a plurality of point scatterers located in the area of interest. The varying D.C. interference signal of the plural radar return signal samples occasioned by the differing frequencies are detected and a one-dimensional Fourier transformer is performed on that composite radar return signal samples to facilitate target identification. A programmed processor is used to dervie a plurality of feature characteristics from the Fourier transform of the detected radar return signals and the features so computed are compared with features characteristic of known potential targets on a best-match basis.

Abstract: This arrangement comprises a fixed frequency emitter circuit (10) for directing a wave (12) to a surface (2) by means of a transmission antenna (11), a receiver circuit (25) for receiving by means of at least one receiving antenna (23) the wave (12) returned by the surface, and a processing circuit (30) for processing the return wave and enabling production of an indication of the velocity. The processing circuit has two branches (50 and 54), a direct branch for applying the received signal to one input of a multiplying member (52), and a delaying branch for applying the received signal to the other input of the multiplying member after having produced a delay t.sub.0 relative to the direct branch. A frequency estimating element (60) receives the multiplying member output signal and a calculation member (62) produces the indication of the velocity from the estimating member output signal and of the distance "h".

Abstract: An extended depth-of-focus synthetic aperture radar (SAR) system (13) mounted on a moving platform, including a controller (120), pulse timer (83), synthesizer (105) and modulator (17) for varying the pulse rate interval (PRI) and/or the radar carrier frequency of radar pulses produced, in order to establish a radar return which, when conventionally processed, results in a SAR terrain map exhibiting extended depth-of-focus under conditions of platform acceleration. Depth of focus is established by ensuring the establishment of two or three separate, independently selected focal points in a target region of interest.

Abstract: The present application discloses a ship collision preventive aid apparatus in which a radar picture and a key picture are selected from all pictures displayed on a display means as transmitted through a touch panel, and the operator touches the surface of the touch panel, so that a program for an operation key name selected is executed. Predetermined collision preventive aid data required for collision avoidance are then displayed on a display screen.With operation simplified, appropriate information concerning collision avoidance may be supplied and the entire construction is simplified.

Abstract: An extended depth-of-focus synthetic aperture radar (SAR) system (13) mounted on a moving platform, including a controller (120), pulse timer (83), synthesizer (105) and modulator (17) for varying the pulse rate interval (PRI) and/or the radar carrier frequency of radar pulses produced, in order to establish a radar return which, when conventionally processed, results in a SAR terrain map exhibiting extended depth-of-focus under conditions of platform acceleration. Depth of focus is established by ensuring the establishment of two or three separate, independently selected focal points in a target region of interest.

Abstract: An audio signal transmission system to be used on commercial airlines for the discrete transmission of voice conversations emanating from the cockpit of the aircraft automatically to a ground tracking station or a tracking aircraft in an emergency situation, sich as a hijacking, unbeknownst to occupants of the cockpit other than the crew members. The transmission system comprises an audio switching assembly which, when activated, transfers audio signals from a voice recorder assembly normally found on commercial aircraft to a radio transceiver of the aircraft for automatic transmission to ground tracking stations. Activation of the system can occur by a crew member carrying out his normal activities therefore not alerting hijackers when performing either one or both of the duties relating to setting the dual transponder control to a preselected code setting and/or the frequency channel selector of the radio transceiver to a preselected frequency.

Abstract: A radar return image for display on a cockpit CRT is generated by selectively accessing terrain data compressed and stored in a digital map data base and processing that data to artificially simulate a radar return image pattern on a cockpit display which effectively corresponds that which would otherwise be provided by conventional T/R equipment. Since the compressed data base contains information representative of both the elevation and cultural features of the terrain at map locations that are capable of being intercepted by the aircraft's radar beam, this data may be subjected to signal processing functions to establish pixel intensity control signals by way of which a radar image of a cockpit CRT display is generated.

Abstract: Composites are produced which are adapted to cover structures which are to be shielded from detection by electromagnetic radiation. The composites are in the form of a substrate, such as Mylar film or the like, having on at least one surface thereof a layer of ferrite having dispersed therein discrete particles of a ferromagnetic metal or ferrite, the composite having a high dielectric constant and a high magnetic permeability. The orientation of the particles is such that their planes are parallel to each other and to the plane of the first said ferrite. The particle thickness is substantially less than the electromagnetic skin depth of the particles and the length of the particles is substantially less than the wave length of a predetermined electromagnetic radiation.

Abstract: A radar warning receiver for detecting and analyzing radar signals comprises a plurality of RF heads each tuned to a predetermined frequency band and connected to an antenna covering a preselected sector of reception of radar signals. Each of the heads includes a frequency converter converting the received signals to a common frequency base-band and producing an output signal in the base-band corresponding to the signal received by its antenna.

Abstract: A radar system for subsurface inspection comprising a short pulse transmitter, an antenna for radiating signals to and receiving external reflections from the surface and from below the surface being inspected, a receiver connected to the antenna for generating an output signal in response to the external reflections, and a clutter cancellation circuit for eliminating internal reflections developed in the system to prevent interference by such internal reflections with the desired external reflections to enhance the system detection capability and reliability of evaluation of such external reflections. Clutter cancellation is accomplished by storing the internally generated clutter and subsequently subtracting it from each incoming radar range sweep consisting of surface and subsurface signals plus unwanted clutter.

Abstract: A ground speed determining radar system for take off roll and landings and roll out maneuvers has a ground based modulating radar reflector and a carrier based radar. The radar transmits microwave energy to the reflector where it is modulated by rotating spaced reflectors and returned to the radar receiver. The receiver is a heterodyne receiver having a log IF stage and a fast time control (FTC) circuit for attenuating clutter and an acquisition loop circuit, lock-on circuit and tracking loop circuit. The acquisition loop circuit includes a center, gate, modulation bandpass filter, switch, acquisition sweep generator and gate generator; the lock-on circuit adds a delay line and a good data indicator to the loop acquisition circuit, and the track loop circuit includes early/late gates, early/late gate low pass filters, subtractor, integrator, the switch and gate generator.

Abstract: Improved radar guidance system for the navigation apparatus of an aircraft s it flies over substantially flat terrain with random and different features. The system is generally made up of an airborne radar altimeter, a video signal processor and a master processor. The altimeter transmits a series of pulses at predetermined time intervals for impacting a plurality of spaced points along the aircraft ground track. The echo signal of each pulse-impacted point processor divides the amplified signal into corresponding signals. A comparator of the signal processor transforms one of the divided signals into a constant output. A track and hold arrangement of the signal processor correlates the delayed leading edge of the comparator output with the other of the divided signals so as to determine a point of intersection therebetween.

Abstract: Disclosed is a system for high speed conversion of radar formats from polar coordinates to cartesian coordinates. From an initial address X.sub.i Y.sub.i where a radar pulse crosses a display, subsequent addresses are determined by adding constant values sin .theta..sub.i and cos .theta..sub.i to X.sub.i and Y.sub.i. This is faster than the prior method of calculating x.sub.i and Y.sub.i by multiplying R.sub.i (range) by sin .theta..sub.i and cos .theta..sub.i. Also disclosed is a system for filling the display between adjacent radials at long ranges where spoking of the display tends to occur. This is done by adding constant increments to one cartesian value on one vector until the next vector is reached while maintaining the other cartesian value constant.

Abstract: A radar method and apparatus which utilizes a first frequency signal modued by a first modulating signal and a second frequency signal modulated by a second modulating signal, the first and second frequencies being different and the first and second modulating waveforms having different periods of repetition. The radar receiver separates the return radar signal into the component due to the first frequency signal and the component due to the second frequency signal. Both components are then heterodyned with their respective frequency signals. Each modulating waveform is subjected to a plurality of delays and each component is subsequently correlated with each of its respective delayed modulating waveforms. A target is recognized when the correlated first frequency component exceeds a predetermined threshold and simultaneously the correlated second frequency component exceeds a predetermined threshold.

Abstract: An outdoor microwave transceiver area intrusion detection system includes circuitry for both amplitude and frequency modulation of the microwave carrier signal pulses, which are transmitted at approximately a 50% duty cycle pulses, from a radar antenna to a target. The return signal is mixed with a portion of the transmitted signal to produce first and second doppler frequency signals which are amplified and sampled during a narrow gating pulse. The two resulting sampled doppler frequency signals are alternately switched, in synchronization with the amplitude and frequency modulation signals, into first and second sample/hold circuits to reconstruct the first and second doppler frequency signals. The reconstructed signals are coupled to a differential amplifier to obtain a "range signal" which is proportional to the phase difference between the first and second doppler signals.

Abstract: For an aircraft radar arrangement, particularly helicopters, a first frequency is provided at a maximum of atmospheric attenuation and a second frequency near the first frequency in a region of less atmospheric attenuation, preferably at 60 GHz and 50 GHz. The first frequency serves to provide obstacle warnings, the second to provide for moving target detection and navigation. The mm wave components of the arrangement can substantially be used for both frequencies so that significant savings in weight, space and costs result.

Abstract: A baseband receiver with a range gate interval in the order of nanoseconds. A tunnel diode, set to the low level state, is coupled across the output terminals of a bridge that is balanced in the absence of a received signal, during the range gate interval. Signals received by an antenna are coupled to a tunnel diode in an arm of the bridge causing it to change from its low level state to its high level state thereby unbalancing the bridge and establishing a voltage at the output terminals of the bridge that fires the tunnel diode coupled thereacross.

Abstract: An adaptive, fail-soft digital filterbank for digitized Doppler-modulated video signals. A plurality of modules are controlled by the impulse filter weighting technique to each respond to a set of discrete Doppler frequencies. A built-in test feature is included, the module inputs being multiplexed between system digitized video and synthetic signals to continuously confirm proper operation. Module failures are recognized by the control (programming) circuitry and spare modules can be activated. Control and communications link circuitry is constructed with multiple redundancy.

Abstract: The conventional way of achieving an identification, friend or foe (IFF) function for a moveable subject requires the subject to carry a transponder that emits a coded return when a radar pulse is received by its receiver. In the present invention, an IFF system is disclosed which departs from the conventional transponder method and employs no radio-frequency power source. Instead, it uses the scattering or reflecting properties of an antenna to modulate, in a distinctive manner, the radar return from a moveable subject. A binary sequence code generator modulates the impedance of a receiver antenna, with the reflected signal being detected and correlated with a synchronized code sequence at the radar.