Abstract: An improved classifier estimates a classification of a sensed object. Data representing the sensed object are received by a sensor, such as a radar, and transformed into wavelet transform coefficients. A subset of the wavelet transform coefficients are selected, the number of coefficients in the subset being fewer in number than the size of the original data. The subset of wavelet transform coefficients is then used in place of the original data by a classifier that generates the classification of the sensed object. The classifier may be a correlation (profile matching) classifier or a quadratic classifier. In another embodiment of the invention, a wavelet fusion classifier further improves classifier performance by taking data from a single sensor, and transforming it into a reduced subset of wavelet transform coefficients for use with a correlation classifier, and also transforming the data into a reduced subset of wavelet transform coefficients for use with a quadratic classifier.

Abstract: A circuit is disclosed for detecting RF pulses, regardless of the frequens associated therewith. Such pulses are characterized by envelope configurations of a common frequency and perceived with a frequency analyzer that responds to that common frequency. In the preferred embodiments, a static Chirp-Z analyzer is incorporated when narrow pulses are of primary interest and a dynamic Chirp-Z analyzer is incorporated when wide pulses are of primary interest. In other embodiments, static transform gain is enhanced with dynamic transform gain.

Abstract: An optical chirp processor for the collection and processing clutter samples is presented that allows the simultaneous estimation of both the clutter mean and variance. The estimated clutter mean and variance allow the actual calculation of both clutter model parameters using a power spectrum analyzer, and a CFAR special purpose processor unit. The power spectrum analyzer is composed of: a spatial frequency demultiplexor, and a four element photodetector array. The special purpose processor is composed of: an A/D converter, a square root calculator, an averaging calculator, a combiner unit, a parameter memory unit, and a threshold calculator unit. The components of the CFAR processor may be implemented in a conventional CFAR processor (when modified by the teachings of the present invention) or in individual electronics components.

Abstract: A method of spectral estimation of a received radar signal wherein an image of the received radar signal is applied to windows of differing prolate spheroidal sequences to calculate multiple eigenspectra. The value of each of said sequences are multiplied with the radar signal, and the Fourier transforms of the products provide a plurality of realizations of orthogonal eigenspectra. The orthogonal eigenspectra are combined into a minimum variance, low bias estimate of the mean power spectrum and an estimate of a variance of said spectrum for each frequency in the spectrum to provide a more accurate estimate of back ground noise and to further improve detection performance.

Abstract: An electronic surveillance system for detecting unauthorized persons within a building. The system comprising a microwave transmitting/receiving device which transmits a microwave signal into the area under surveillance and receives microwave signals reflected from the area. The microwave signal having frequencies corresponding to the life functions of any living beings present in the area. The transmitting/receiving device comprising a signal conditioning device, a memory device, and a comparator unit. The signal conditioning device adjusts the amplitude and phase of a portion of the outgoing microwave signal and adds it to the incoming microwave signal, eliminating the carrier wave. The resultant actual signal is transmitted to the comparator unit which also receives a signal from the memory device comprising characteristic frequencies representing authorized occupants. If the results of the comparison are above a predetermined threshold, an alarm is generated.

Abstract: A radar system includes a radar transceiver for generating transmit signals and for receiving signals reflected by targets. The radar system includes a mixer for combining the transmit signals and the reflected signals into a mixer signal. A radar signal processor includes a sampling device, connected to the mixer, for sampling the mixer signal and for generating a sampled mixer signal. A spectrum estimation device, connected to the sampling device, generates a range profile signal including a plurality of range bins each containing a magnitude of a spectral component. A threshold device, connected to the spectrum estimation device, generates a target space array from the range profile signal. A target decision device, connected to the threshold device, generates estimated range and speed signals for a closest target from the target space array.

Abstract: A solution to the AOA problem is provided, receiving the data via a plurality of antennas, which uses a switching network to couple the antennas to a single receiver and a single analog-to-digital converter to digitize the incoming signal. It is possible to solve the problem where there might be multiple signals present. In the receiver, the incident radiation is mixed with a local oscillator signal and down converted to an intermediate frequency (IF). This IF signal is discretely sampled in the analog-to-digital converter, and further processing is done using digital techniques. The incoming signal has to be phase compared to obtain the angle of arrival. Different delay times are used to receive the digital data from the different antennas at the same sampling times, with the data aligned according to the time axis. The frequency of the incoming signals can then be detected by performing a Fast Fourier Transform (FFT) on the data from one antenna with respect to time.

Abstract: The maximum likelihood function can be simplified by exploiting the symmetry in the equations. This new representation leads to a very significant decrease in the computational load for bearing estimation and spectral analysis applications.

Abstract: In a method for measuring the distance and the velocity of objects employing electromagnetic waves, the frequency of an emitted signal is modulated. The signals received during one rise and one drop in the frequency of the emitted signal are mixed with the emitted signal. The intermediate-frequency signals resulting from the mixing are then spectrally analyzed. The distance and the velocity of at least one object are calculated from the frequency of the spectral lines of the intermediate-frequency signals during at least one rise and at least one drop in the frequency of the emitted signal.

Abstract: Improvement of radar sign-to-noise ratio and detection sensitivity in radar systems is achieved by methods employing the subtraction of the unwanted radio frequency interference, RFI, or "clone" signals thereof, from the total received signal. The Clone signals are appropriately adjusted in phase and amplitude, and are obtained from an auxilliary broad beam antenna or from a delayed sample from the system's principal antenna. When multiple RFI signals at different frequencies are present, the entire receive band is subdivided into a plurality of frequency sub-ranges.

Abstract: A method of obtaining oceanographic and meteorological data from high frequency radar spectral information including the steps of transmitting a plurality of signals to a remote geographic location, recording signals backscattered from the said location, generating a family of Doppler clutter spectra from the recorded backscattered signal and analyzing the Doppler clutter spectra in terms of a model or models to generate oceanographic and meteorological data estimates. The Doppler spectra are categorized according to Suitability for Deatiled Analysis (SDA). The SDA takes account of the clutter-to-noise ratio in the spectrum, the amplitudes of the Bragg-lines, multimode propagation, spectral broadening and other spectral parameters. Spectra with a low SDA are inappropriate for extracting directional wave spectrum estimates of reasonable accuracy but are useful for obtaining wind direction estimates.

Abstract: A method and apparatus for processing the log video output of a receiver that can measure multiple time overlapped pulses on a nearly instantaneous basis. The receiver measures frequency, pulse modulation, time of arrival, amplitude, pulse width and phase difference when simultaneous pulses are present. To detect pulse parameters a given voltage threshold must be exceeded and M out of the last N data samples must fall within a given voltage window that is above the threshold voltage. Pulse detection is initiated by establishing a dynamic noise threshold that is above the random noise level. When a pulse arrives, the value of the amplitude samples are measured and when the successive differences between the amplitude samples are small enough then a pulse presence is declared. Following detection of a pulse, amplitude samples are continuously taken and processed to detect the end of the pulse or a pulse-on-pulse condition.

Abstract: A detection system will detect and identify self-propelled objects, such as missiles, which create a hot exhaust plume. The exhaust plume has radiation which flickers with a frequency range of interest. This frequency range can be detected with various detectors, such as an ultraviolet detector or radio frequency detector. A warning signal will indicate if frequencies are encountered within the frequency range of interest. The detecting system will also detect light and radio frequency radiation from pressure waves created by supersonic components of the flying object. This radiation has low frequency components which can be filtered and identified.

Abstract: A distant target vibration assessment and signature determining apparatus for operation from a vibrating platform such as an aircraft or helicopter. The disclosed system employs pulse illumination of the distant target and of nearby atmospheric aerosol particles and uses the latter illumination derived signal as a characterization in reverse of the vibrations of the sensor's mounting platform. The nearby and distal nature of the two illuminated energy reflections enables their range gated segregation and individual transformation into the frequency domain. Frequency domain vibration signatures of the distant target and the vibrating platform are then individually obtained and subtracted in order to obtain a clean vibration spectrum representation of the distant target. Variations of the system including a two pulse operating cycle, the use of signal strength evaluation and signal processing alternatives are also disclosed.

Abstract: A radar system transmits dispersed pulses, and receives echoes from targets. The echo signals are digitized and applied over a number of signal paths. In each signal path except one, the digitized signal is multiplied by one of a plurality of differential exponential signals, for converting the echo signal of different exponential signals, for converting the echo signal in each path to baseband, with the baseband frequency representing a particular Doppler which depends upon the exponential signal. In the one remaining signal path, no multiplier is used, and the echo signal is deemed to be at baseband. The signals in each path are applied through a cascade of a pulse compressor and a range sidelobe suppressor. Since Doppler filtering has not yet taken place, full compression and range sidelobe reduction is not achieved, because of extraneous pulse-to-pulse phase shifts.

Abstract: A functional radar warning receiver backup generator. A functional radar warning receiver backup generator provides threat information in the total absence or partial absence of the radar warning receiver information. Radar warning receiver information such as radar detection data and radar identification data is also generated by other systems such as the Pulsed Radar Jammer and the Continuous Wave Radar Jammer. An on-board computer processes and presents the back-up information to the pilot as if the Radar Warning Receiver was still operational. Voice and video functions of the Radar Warning Receiver are also displayed and presented to the pilot. Partial back-up and full back-up of the Radar Warning Receiver are provided. A temporal data correlation algorithm, a radar emitter ID conversion algorithm, cross sensor correlation algorithm and prioritization algorithm provide the back-up data.

Abstract: A spectral moment estimator includes a first processor which processes signals representative of the magnitudes of complex autocorrelation functions of a signal at a plurality lags and provides Doppler spectral width representative signals and the autocorrelation function at zero lag independent of noise. A second processor, processes the complex autocorrelation representative signals, the complex autocorrelation functions phase angles representative signals, and the Doppler spectral width representative signals to provide the mean Doppler frequency of the the signal. The autocorrelation function phase angles are disambiguated and the unambiguous phase angles are least mean square error fitted to a third order odd polynomial, the linear term of which is the mean Doppler frequency of the signal.

Abstract: A compressive receiver of the type having a dispersive delay line is provided by an additional mixer which is responsive to the compressive receiver's local. oscillator and to an additional RF input. The output of the additional mixer is delayed and applied to the input of the dispersive delay line. The output of the dispersive delay line is divided, one of the divided outputs being delayed. The delayed output and the other dividend output are compared in a comparison circuit. The compressive receiver may be advantageously used as a direction finding or side lode cancelling compressive receiver.

Abstract: In a method of recognizing a radar target object type, target range, heading and speed information are determined. A plurality of RCS for different targets of interest as a function of frequency and aspect angle are stored. Motion information of a platform on which a radar system is carried is determined. The target range, heading and speed information and the motion information of the platform with stored RCS, are processed, and what the observed radar pulse echo should be over the operational frequency band is predicted therefrom. Predicted information is compared with the measured pulse echoes to determine which target is present.

Abstract: A conical scan radar system (10) provides return pulses (30) to an A/D converter (38) from which a shaped pulse train is received and stored in a FIFO memory (40). The stored pulse train is then passed through first and second finite impulse response filters (42,44) for achieving sampling rate reduction prior to rendering via a programmable signal processor (64) of target detection identification and tracking.

Abstract: Disclosed is an apparatus and method for separately tracking, identifying and providing DF on LPI RF transmitters. Intercepter circuitry which includes an antenna and a single channel receiver is utilized to receive and down convert LPI RF signals to LPI IF signals. Digitizer circuitry is utilized for down converting the LPI IF signals to LPI baseband signals as well as utilized for converting the LPI baseband signals to digital data. A spectrum analyzer generates power spectrums utilizing the digital data and passes the power spectrums to a signal detector. The signal detector detects signal clusters in the power spectrums and associates the signal clusters from the same LPI RF signals to create pulse descriptor words for the LPI RF signals.

Abstract: A radar processor is disclosed for processing the radar return samples from a Doppler radar receiver to discriminate helicopter targets from fixed-wing targets. The samples are passed through a helicopter filter which eliminates the target skin Doppler return, and passed the sidebands about the target skin return which are due to the helicopter rotor hub modulation. The coefficients of the helicopter filter are selected to maximize the signal-to-noise ratio. The radar processor requires only a few milliseconds on target for reliable detection and can, therefore, be easily implemented by scanning surveillance systems.

Abstract: The input ports (18) of an imaging compressive receiver (20) receive from a tapped delay line (16) progressively delayed versions of a received signal s(t). Because of the delays, a signal component in the received signal appears at least at one of the input ports (18) of the compressive receiver (20) at a time when the compressive receiver (20) will detect it, even if the undelayed version occurs during a time at which the compressive receiver (20) would ordinarily be insensitive to it. Since the compressive receiver (20) is an imaging device, it provides relatively isolated channels between its input terminals (18) and its output terminals (38). The phase relationships between the delays in these channels remain constant despite changes in environmental factors, however, because the various channels are embodied in a common two-dimensional delay line.

Abstract: A processor for an FM/CW sensor divides the sweep periods of the sensor into a number of subsweep intervals, measures the received power within a multiplicity of frequency windows during each of the subsweep intervals, and then performs a spectrum analysis of the power measurements in each frequency window to characterize the reflectors in the corresponding range bins of the FM/CW sensor footprint.

Abstract: A method and apparatus for classifying objects based upon information conned in the fourth order cumulant derived from energy from the object. Successive pulse returns in active systems and samples in passive systems are converted into vectors based upon the fourth order cumulant information for each successive return or sample. The vectors for each such pulse are compared to corresponding class information based upon the corresponding fourth order cumulant information. The comparison uses loglikelihood ratios of the different pairs of classes. Decision making is based upon the value of each loglikelihood ratio in comparison with a class threshold.

Abstract: The circuit may be used to encode the channel outputs of a Bragg cell receiver, or other type of channelized receiver. Bragg cell receivers use acousto-optic delay lines to analyze signals such as radar pulses present in the Electronic Warfare (EW) environment. These receivers require high probability of intercept with low false alarm rates. The present design in determining frequency from a Bragg receiver is by comparing the amplitude from adjacent outputs. If the output of a certain channel is higher than its neighboring ones and the signal crosses threshold, the frequency of the input signal is determined by that channel. There is one major deficiency from this approach, that is, the design generates false alarms. A frequency encoding circuit is proposed which uses five adjacent channels to make a decision on whether a given output is a true signal, or a false alarm. With this approach, two guard channels will be needed at both ends of the channels.

Abstract: A microwave apparatus and method for ullage measurement of agitated materials is provided. The apparatus and method utilize a transformation of the reflected time domain signal into a frequency domain signal. The frequency domain signal is averaged using the natural, inherent weighting associated with the transformation to achieve a unique corrected result. The average frequency domain signal is then used to calculate the average distance for determining the ullage measurement.

Abstract: Systems and methods that use a CW Doppler radar to monitor paint particle velocities as they are sprayed from a paint gun to optimize the application of sprayed paint onto the object, and provide a closed loop spray painting system and paint spraying method that controls the application of paint in real time using data generated by the radar. The Doppler radar and a signal analyzer are used to analyze the Doppler return signals and display data indicative of the velocity of the paint particles. The data may be used by an operator to manually adjust the paint spray system. In addition, the spectrum analyzer may be used to generate and couple control signals to the paint spray system to provide for closed loop feedback control of thereof. One method comprises the following steps. Spraying paint particles toward an object that is to be painted using a paint spray gun. Radiating Doppler radar signals at the paint particles that are moving toward the object.

Abstract: A radar system includes a doppler/pulse compressor/range sidelobe suppressor filter bank (40), which separates received echo signals according to their frequency spectrum into doppler channels, and within each doppler channel performs pulse compression for reducing the duration of the received signals, and also performs range sidelobe suppression, for improving range resolution. It may be advantageous to perform certain types of processing in the time domain, such as determination of spectral moments for estimating velocity spread, mean closing velocity, and reflectivity of a diffuse target such as a weather phenomenon. An inverse (frequency-to-time) transform (50) is performed on the signals produced by the doppler/pulse compressor/range sidelobe suppressor filter bank (40), to produce a reconstructed version of the received signals. In these reconstructed signals, the pulses are compressed, and range sidelobes are reduced. The time-domain processing (62) is performed on the reconstructed signals.

Abstract: A small target phased array Doppler detection system receives signals from remote moving targets and determines Doppler frequency shift and the respective powers of coherent electromagnetic signals for the purpose of detection and identification of relatively small, slow moving targets in the presence of scattering echoes due to clutter. The system employs covariance analysis of the received signals followed by eigenanalysis to produce eigenvectors and eigenvalues. A superresolution algorithm creates dwell manifold vectors which indicate velocities of targets from the eigenvectors. The relative power of radar echoes contribute information relevant to the identification of real moving targets as opposed to false alarms.

Abstract: Process for the recognition of an aerial target from samples of its radar echoes. First, Doppler radar emission is transmitted in the direction of the target. A Doppler spectrum echo signal of the target is then detected. At the center of the signal, a principal line corresponding to the aircraft's velocity is detected. The distance between this principal line and secondary lines of the spectrum signal is then determined. From the value of this distance and the relative configuration of the spectrum signal, the target can be classified into a predetermined target category. In this step, in particular, at least one intrinsic parameter of the spectrum signal can be determined, e.g., the number of secondary lines, the intensity of the secondary lines relative to the principal line, the absolute intensity of these secondary lines with allowance for the distance of the target, the equivalent radar surface of the target.

Abstract: A system for distinguishing between a target and clutter analyzes frequency components of returned wave energy by one or more networks each having inputs receiving successive samples of the returned energy and having outputs individually connected to the inputs through multiplier elements providing selectable factors. The multipliers corresponding to each output are connected to the output through a summing element and a selectable and generally sigmoidal activation function. The factors may be bandpass filter coefficients or discrete Fourier transform coefficients so as to generate frequency components of the energy. Predetermined frequency characteristics of the returned energy may be detected by providing the outputs of a network to a network in which the factors are selected as correlation or convolution coefficients, are selected to integrate fed back outputs, or are selected to sum several outputs within a predetermined range.

Abstract: A method for distinguishing between a target and clutter analyzes frequency components of returned wave energy to detect target energy characterized by being present in a narrow range of frequencies, by increasing in the range over time, or by remaining substantially in the range over time. The method utilizes time sequential spectra of the returned energy. The spectra may be signals from a plurality of band pass filters or may be a spectrogram. The energy in adjacent band pass signals and spectra frequencies are correlated to detect energy in a narrow range of frequencies. Differences in successive spectra are integrated to detect increasing energy in a range of frequencies. An energy peak detected in a narrow range by correlation is integrated to detect that the peak remains in the range.

Abstract: To detect and classify a helicopter as a target by means of a radar system equipped with a Doppler filter bank, an initial determination is made as to whether the threshold value has been exceeded in a substantial number of the individual filters of the Doppler filter bank, and if so, the width of that amplitude band delimited by the highest and lowest amplitudes of the filter output signals is determined and a decision regarding the presence of a helicopter target is derived from the width of the amplitude band.

Abstract: While the computation of high resolution radar images based on higher order tatistics is position insensitive, velocity estimation may be based on the ratios of values of a trispectral slice and a cross-trispectral slice computed as quadruple products of complex valued signals developed by coherent radar. Signal-to-noise ratio is improved by either averaging over a plurality of bursts during computation of both the trispectral slice and the cross-trispectral slice or averaging of values of ratios of trispectral slice and cross-trispectral slice values at particular frequencies or wavenumbers, or both.

Abstract: A coherent radar is used for achieving high resolution radar imaging of a moving object in sea clutter and noise. A stored replica of the transmitted waveform is combined with the returned signal in a synchronous detector to produce in-phase and quadrature (I and Q or complex) samples. High resolution is achieved by transmitting a series of pulses, each at a different frequency, and then processing these complex samples to produce a synthetic down-range profile. To enhance the radar target or object from system noise and sea clutter, the complex I and Q (in-phase and quadrature component) samples from the radar are coherently averaged in a special two-dimensional slice of the trispectrum (e.g. quadruple product or fourth-order moment). This formulation of the fourth moment retains all important target information and suppresses Gaussian noise. Once averaged, a new set of I and Q samples are reconstructed that produce the same trispectral slice as this average.

Abstract: An approximate figures measuring system includes a signal transmission device and a signal receiving device. The signal transmission device is arranged in each of any objects to be measured and emits a signal from which a peak can be generated at a receiving device in a predetermined period. The signal receiving device receives the signal transmitted from the signal transmission device and includes a peak detection circuit and a calculation circuit for obtaining an output corresponding to the number of the peaks of the signals from the objects.

Abstract: A Doppler radar speed sensor for a land vehicle comprises a radar transmitter/receiver circuit (1) coupled to an aerial system (2). R.F. energy from a source (3) is transmitted by the aerial system in forward (9) and backward (10) directions and energy reflected from these directions is mixed with a sample of the transmitted energy in a mixer arrangement (8) to yield a pair of Doppler frequency components representative of the vehicle speed. In order to ensure that these components always have mutually different frequencies, and thereby avoid the necessity of constructing the mixer arrangement as a pair of quadrature-related mixers, the forward and backward directions make different angles (.theta.+.DELTA..theta. and .theta.-.DELTA..theta. respectively) with the direction of travel (15).

Abstract: A technique covered by patent applicaton S.N. 07/672,309 divides power of an input signal to two A/D converters. A processor receives the outputs of the two A/D converters. The input signal is subjected to a known delay .tau. for one of the converters, and both original and delayed signals are sampled simultaneously. Both sampled signals are Fourier transformed and the phase and amplitudes calculated, using the expressions:.phi.(f)=tan.sup.-1 [I(f)/R(f)]A(f)=[R.sup.2 (f)+I.sup.2 (f)].sup.1/2where R(f) and I(f) are respectively the real and imaginary parts of the frequency transform. The phase difference between the original and delayed signals is calculated and an approximation to the true frequency for each peak observed in the amplitude spectrum is estimated using the expression.phi.=2.pi.f.tau.where .tau. is the delay. Herein the input signal is down-converted into two parallel paths with frequencies which differ by f.sub.s /4 where f.sub.s is the sampling rate. The alias boundaries are at multiples of f.

Abstract: A method and apparatus detects and identifies targets using a laser and operating in accordance with Doppler radar techniques. A laser sensor comprises a laser transmitter and an optical superheterodyne receiver and detects characteristic surface vibrations of targets and derives, from the laser echo signals, after frequency conversion and demodulation, low frequency oscillations having the frequencies of the vibration spectrum, from which, through comparison with patterns of known targets, provides detection and identification of the target.

Abstract: A device automatically measures a distance relative to the longitudinal axis of a runway to be destroyed. This device comprises: a radar transmitter-receiver, at least one depointed antenna, distance-measuring gates, a threshold circuit and a computer circuit.

Abstract: Parallel architectures preprocesses large matrices from sampled coherent time apertures receiving signals from distant sources to produce lower order matrices, derived from pseudo coherent time apertures, which are computationally less burdensome. The large matrices are processed by frequency shifting, low pass filtering with an FIR filter, and executing front-end decimation to create the pseudo coherent time apertures, each corresponding to different subbands of the temporal frequency spectrum. The signals representing the pseudo coherent time apertures are processed using matrix based superresolution spectral estimation algorithms such as the Tufts-Kumaresan (T-K) reduced rank modified covariance algorithm and the Linear Minimum Free Energy algorithms to produce an image of the sources.

Abstract: An adaptive RADAR environmental signal filter (1) is described which selectively preprocesses RF RADAR input data prior to the data's utilization by a processor (8). The filter (1) consists of an array of parallel discriminator cells (165) which compare incoming RF RADAR data to a window parameterized by predetermined threshold values. The array of discriminator outputs are networked through combinational logic (59) in order to provide an output correlation signal (63) to an external processor (8). A discriminator enable latch (55) synchronizes the discriminator outputs as the outputs pass through the combinational logic (59).

Abstract: An acousto-optical classifier for classifying wide bandwidth signals such as high resolution radar returns of ships or very short pulse length signals of radar emitters. This is accomplished by generating the Fourier transform power spectrum with an acousto-optic cell oriented in the Bragg configuration and a low power coherent light source such as a laser. The power spectrum is detected to provide inputs to a digital classifier.

Abstract: The invention relates to a device and process which utilize the Doppler effect for measurement of the performance of blasting operations, in particular to the measurement of face velocity. The measuring device comprises radiation generating and receiving means and a signal analyzing means.

Abstract: A radar detector including a local oscillator capable of sweeping over a frequency range of sufficient bandwidth to provide a fundamental frequency and, when injected into a multiplier/mixer, harmonics of that fundamental frequency suitable for heterodyning with rf-signals received by an antenna. The heterodyning of the received rf-signals and the local oscillator signal produce an intermediate frequency signal of constant frequency. A sweep controller causes the local oscillator to sweep only through those local oscillator frequencies suitable for heterodyning with those received rf-signals having radio-frequencies which are of interest. The sweep controller causes the sweeping local oscillator not to sweep through those local oscillator frequencies which would heterodyne with received rf-signals that are not of interest.

Abstract: A radar antenna arrangement (1) for a determination of the effective radar backscatter cross section .sigma..sub.eff of radar targets (2) as a function of the geometrical position of the target with reference to the radar antenna arrangement to be able to determine the effective radar backscatter cross section in a simple manner, even for a case where the radar beam no longer fully illuminates the radar target (2) to be examined and the position of the phase center (15) of the antenna (11) changes relative to the target (2), the radar antenna (11) is arranged on a rotatable antenna platform (10) outside of the rotation axis (12) of the antenna platform (10). In order to be able to scan the entire radar target (2) successively in time, the antenna platform (10) is pivotal about two axes (13, 14) that are perpendicular to the rotation axis (12). The radar target (2) to be examined is disposed on a revolving platform (3) which likewise rotates during the measuring process.

Abstract: A method and apparatus for detecting the occurrence of a fire or an explosion in a monitored space, or the penetration of a projectile through a barrier, by: transmitting to the monitored space an electromagnetic signal of at least one radio frequency; receiving the transmitted signal as scattered by the monitored space; and analyzing at least one parameter of the received signal to produce an indication whether a fire or explosion has occurred, or a projectile has penetrated through a barrier, in the monitored space.

Abstract: This radar system comprises an emitter (3, 4, 5) for the transmission of coherent non-equidistant pulses forming a periodic pattern and being distinguished from each other by a phase modulation according to different quasi-orthogonal laws, the average interval between pulses being of the order of magnitude of the minimum duration of the flashes. For reception, the system comprises a single receiver (7) and a device (8) for coherent elimination of the clutter and echoes of the target bodies, followed by N processing channels for pulse compression (9.1 to 9.N) by correlation with the particular phase modulation laws. The outputs from the processing channels are sent to a device (11) for elimination of secondary peaks due to partial ambiguities.The invention applies to radar surveillance systems for helicopter detection.

Abstract: An optimized theoretical approach to the design of a waveform for a matched illumination-reception radar system incorporates radar cross section codes along with detailed target geometry and system constrains to maximize the signal energy of a received echo. An Eigensystem is used to generate a family of solutions, one of which is chosen based upon system constraints to optimize the waveform.