Abstract: A microwave deviation measurement receiver particularly applicable to airborne secondary radars making deviation measurements with two logarithmic amplifiers which increase the reliability of deviation measurements for targets close to the direction of aim of the radar. A programmable phase shifter preferably is controlled to compensate for aircraft movements by shifting the phase of the sum or control signal.

Abstract: An angular scintillation reduction device used more especially in radar equipments making deviation measurements.It contains a circuit (60) receiving the video outputs of a radar receiver, the sum .SIGMA., range D and deviation measurement .epsilon. signals respectively on three terminals (3, 28 and 2). It delivers on a terminal (30) the values of the deviation measurement signal .epsilon. corresponding to the maximum values of the sum signal .SIGMA..It is applicable to all electromagnetic detection equipments which make deviation measurements.

Abstract: According with the present disclosure to provide a suitable protective headgear for the sports vehicle operator/motorcyclist that incorporates internal radar detection electronics capable of detecting X and K band radar signals as well as any future bands that may be used. To provide both audio and visual alarm signals that will allow the operator to adjust speed accordingly to avoid violations. To provide the light panel display in the vision proximity of wearer so that the operator never has to look away from their immediate trajectory. To provide ventilation for both the wearer and the electronics inclosed therewith that would compensate for any additional heat caused by the electronic circuitry. Helmets would be sized to fit different size heads with a comfortable snug fit.

Abstract: A method and apparatus for imaging a target, such as a ship, exhibiting rotational movement about respective, mutually orthogonal axes. The method involves identifying a scattering center at the target exhibiting rotational movement about one axis only (the yaw axis, say, in the case of a ship) and then correlating an electrical signal related to the Doppler frequency of a return derived from that scattering center, and indicative of the angular velocity of the target about the one axis, with other electrical signals related to the Doppler frequencies of returns derived from other scattering centers. Correlation signals generated in this way provide an indication of the relative positions of the other scattering centers in relation to the one axis.

Abstract: A system for simultaneously locating a plurality of targets and distinguishing the targets from noise which utilizes phase detector techniques to generate complex voltage signals and obtain phase information. Spectral analysis is performed on the complex voltage temporal functions to generate doppler frequency functions. Both spectral phase functions and spectral amplitude functions are generated from the doppler frequency functions. Spectral phase functions are analyzed using interferometry techniques to determine if a potential target has a common locational source from returns of a plurality of sensors. A zenith angle is also generated using interferometry techniques to provide locational information of the multiple targets. Range gating and two frequency range detection methods provide high resolution range information as to the location of the targets. High resolution range information and two dimensional zenith angle information are used to provide an image of the targets.

Abstract: Vehicles are measured and photographed from the direction in which they are travelling by a Doppler radar speed measuring device equipped with a camera. During a measuring stage after the vehicle enters the radar beam, a measured speed value is determined and when this exceeds a specific limit value, the camera is triggered. The Doppler signal for checking the measured speed value is then further evaluated over a verification distance. If the measured speed value is confirmed then it is printed on the photograph at the end of the verification distance, if it has not been confirmed, then a cancellation indicator is printed. The film is then advanced and the detection of the entry of another vehicle is awaited. As a result of this checking of the measured speed value, the measuring reliability when registering oncoming vehicles is substantially increased and overtaking in particular can be detected in the range of the radar beam.

Abstract: A very wide pass band polarization diplexer having a power divider, a transition element and a wave guide containing an impedance adapter, and applicable to all devices requiring the use of a wave guide in which two waves in orthogonal modes propagate.

Abstract: A super resolution imaging system employing coherent radiation comprises transmitting, receiving and processing means to provide complex amplitude image data. The image data is processed by a weight function generator to provide a weight function. The weight function has values at individual image pixels consisting of a background or clutter intensity term added to a pixel intensity dependent term. The latter term is non-zero for pixel intensities exceeding a threshold level well above background. A computer generates singular functions from the weight function and system impulse response, and employs the singular functions to decompose the image data and subsequent object reconstruction. This provides enhanced resolution compared to that available from the image data alone. An iteration controller employs the reconstructed object data to iterate resolution enhancement until no significant improvement is obtained.

Abstract: A Radar Altimeter static accuracy circuit which provides improved system accuracy when the altimeter platform is stationary over the ground. Most often this stationary condition occurs in helicopters while hovering at low altitudes but also occurs, for example, in altimeters used to measure the level of grain in elevators. The altimeters output, a voltage proportional to altitude, is used to control a voltage controlled oscillator (VCO), the output of which is summed into the receiver intermediate frequency (IF) amplifier output to fill in the return signal fades. These fades otherwise cause altitude processor errors leading to erroneous altitude measurements. The VCO is adjusted to produce an output frequency equal to the IF amplifier output frequency.

Abstract: A pulse doppler radar having variable repetition rates, noise pulses resulting from echos received from stationary multiple-time-around objects are removed by subjecting the reflected pulses to a coherent integration modified by means of a simplified vectorial addition of the reflected pulses, using an integration circuit consisting of a plurality of filters.The signal amplitude produced at the output of each filter is individually compared to the mean value of signals produced by all other filters, and a target indication is produced when the mean value is exceeded by the amplitude of a signal from an individual filter.

Abstract: Apparatus for measuring the phase noise content of a microwave signal source (10) includes a microwave cavity (22) resonant at a fixed frequency, signal generating means (23) operable to generate a frequency representing the difference between the source frequency and that of the resonant cavity, and mixing means (20) for combining the outputs of the source and the signal generating means. The output from the resonant cavity (22) is applied to a phase detector (15) together with a portion of the output of the mixing means (20) and the output of the phase detector (15) represents the phase noise content of the output of the microwave source (10). The signal generating means (23) includes a voltage-controlled oscillator the frequency of which is controlled by an output from the phase detector means (15) so as to maintain the output of the mixing means (20) at the resonant frequency of the microwave cavity (22).

Abstract: The apparatus according to the invention relates to a guided vehicle control process and apparatus which comprises passive beacons, as well as radars permitting the detection thereof. The presence or absence of a beacon permits the automatic control of a train, e.g. with a view to automating the driving thereof. The apparatus according to the invention uses retrodirectional beacons and/or beacons inducing a polarization rotation of the radiation received. The use of retrodirectional beacons induces a change of frequency by Doppler effect of the reflected radiation. The change of the Doppler frequency and/or the polarization rotation of the radiation improves the signal-clutter ratio and/or the separation of the transmission and reception channels.

Abstract: Target support structure for making bistatic radar cross section measurements. The support structure includes two parallel columns of circular cross section that may be coated with radar absorbing material. The rotational angle of the columns and the spacing therebetween are each adjustable to allow the bistatic reflections from each column to be phased to cancel each other at a selected bistatic angle and thereby minimize the background signal from the support structure.

Abstract: The method of the invention, applied for example to estimating the parasite phase .phi..sub.a between the azimuth sum .SIGMA..sub.a and difference .DELTA..sub.a channels, consists in calculating the expressions S=.SIGMA..sub.a .multidot..SIGMA..sub.e * and D=.DELTA..sub.a .multidot..SIGMA..sub.e * for different successive measurements made by the radar, then in calculating the expressions [S.sub.(k+1) -S.sub.(k-1) ].multidot.D*(k) for different successive times k-1, k, k+1 and in averaging the result of this expression or different times k, it being understood that the radar antenna sweeps in azimuth and that the radar wave emitted is polarized circularly, the single pulse azimuth and elevation receivers receiving respectively only one of the circular polarization types: right hand or left hand.

Abstract: A device for the detection of undesirable echoes which have significant correlation in azimuth which is applicable to surveillance or tracking radars. The device works through autocorrelation function estimation over a pair of pulses received by averaging, over N range cells, the complex product of the received signal Z.sub.k (t.sub.1), relevant to the K-th range bin and time instant t.sub.1, with the complex conjugate value Z.sub.k (t.sub.1 +T), still relevant to the K-th range bin, at instant t.sub.1 +T (where T is the pulse repetition period, PRT).

Abstract: The invention provides a method and apparatus for detecting specialized meteorological conditions, in particular a microburst. The detector is localized so as to process radar return signals from regions in which aircraft are particularly vulnerable to microbursts. The detector includes a Doppler radar and an intelligent processor. Doppler radar returns are stored in an array wherein the contents of each cell identify the wind velocity parallel to propagation path. A pattern matching process identifies the existence of a microburst, maximum wind velocity associated with the microburst, and the location of the center. By tracking the microburst center as a function of time, the microburst velocity and direction can be determined, allowing prediction for microburst location in the future. Based on observed microburst lifetimes, the expected duration of the microburst can also be predicted.

Abstract: A radar receiver having a feed-forward control circuit for adjusting the automatic gain control (AGC) setting in 6 dB increments for each range cell in a next sweep based on the AGC setting of each corresponding range cell in the present sweep, the magnitude of the larger of the in-phase (I) or quadrature (Q) components of the video signals of the present sweep from an A/D converter, the status of present sweep and previous sweep A/D limit conditions, and a selected guardband thereby holding the level of the radar return signal within the dynamic range of the A/D converter. The AGC setting is adjusted using a switchable attenuator which changes the level of the video signal into the A/D converter in 6 dB increments, each increment corresponding to a common I and Q data exponent directly used for floating point signal processing.

Abstract: A pulse radar apparatus is provided with a transmitter and receiver unit (1), a video extractor (2) connected thereto for obtaining digitized plotting data, a plot processor (3) for determining the track positions with the associated digital data from the plotting data obtained in consecutive antenna revolutions, and a display system (5) for presenting both the video signals from the transmitter and receiver unit (1) and the track positions with the associated digital data. The pulse radar apparatus is furthermore provided with a data converter (4) deriving video signals from the plotting data, which video signals, after mixing with the video signals from the transmitter and receiver unit (1) are presented on the display (5) on a real-time basis.

Abstract: An arrangement for selecting between different doppler filter pairs having response characteristics optimized for ground clutter or moving rain clutter rejection. The selecting process detects the amplitude and mean doppler of the received radar echoes. The filter which is optimized for rain clutter rejection is normally used until clutter amplitude is detected above a predetermined value and the mean doppler is detected as being equal to or near zero. When such a detection is made, the filter optimized for ground clutter rejection is selected. Portions of the selecting device allow for the selection to be determined over several samples rather than switching the filters in each sample or coherent processing interval. Another portion of the circuitry changes the predetermined values which must be exceeded for a selection of the ground clutter filter, thereby preventing another filter change with only a small change in detected amplitude or mean doppler.

Abstract: Device for eliminating the noise in 1/f from a Doppler radar comprising in the HF emitting system, a phase coder introducing, at frequency PRF/2 a phase shift of 0 and .pi. alternately, and in the receiving system, after the receiver, a decoder, or gain inverter progrmmable between -1 and +1, acting, in the same manner as the coder, upon the receiving signal and comprising a low-pass filter downstream from the decoder for eliminating the noise in 1/f, that appears at PRF/2, the device being applied to a ground surveying radar.