Abstract: A filter scheme for broadcast interference cancellation that is computationally efficient and numerically robust Airborne Low Frequency Synthetic Aperture Radar (SAR) operating in the VHF and UHF bands has been shown. At least interference Doppler filtering or interference cancellation is utilized. The interference cancellation involves prediction of the interference for each particular reception interval of mixed interference and radar ground response. This prediction is then coherently subtracted from the incoming signal.

Abstract: There are provided a distance measuring device and a distance measuring method characterized by “simple configuration”, “capability of measuring a near distance”, and “a small measurement error” like a distance measuring device using a standing wave. The distance measuring device includes a signal source (1) for outputting a signal having a plurality of different frequency components within a particular bandwidth, a transmission unit (2) for transmitting a signal as an undulation, s mixed wave detection unit (3) for detecting a mixed wave VC obtained by mixing a progressive wave VT transmitted and a reflected wave VRk of the progressive wave VT reflected by a measurement object (6), a frequency component analysis unit (4) for analyzing the frequency component of the mixed wave VC detected, and a distance calculation unit (5) for obtaining a distance spectrum by subjecting the analyzed data further to spectrum analysis, thereby calculating the distance to the measurement object (6).

Abstract: A radar device includes a transmission antenna and a reception antenna having a plurality of antenna elements. The radar device switches the antenna elements in synchronization with a modulation cycle, thereby obtaining a reception signal. At this time, the radar device obtains the reception signal by switching the antenna elements using a first measurement phase and a second measurement phase having different switching cycles as one set. The radar device calculates an azimuth sine value sin ?1 from the reception signal in the first measurement phase and also calculates an azimuth sinusoidal value sin ?2 from the reception signal in the second measurement phase. Then, the radar device calculates a relative velocity V from the azimuth sine value sin ?1, the azimuth sine value sin ?2, an interval time difference ?t between switching cycles, and an inter-antenna element spacing d.

Abstract: The present invention is a method and apparatus that provides detection, characterization, and intuitive dissemination of targets. This disclosure combines improvements to ultra-wideband (UWB) sensing and machine target characterization with a means to convey data in a format that is quickly and readily understood by practitioners of the technology. The invention is well suited for Situational Awareness (SA) support in areas that are occluded by rain, fog, dust, darkness, distance, foliage, building walls, and any material that can be penetrated by ultra-wideband RF signals. Sense Through The Wall (STTW) performance parameters including target range, stand-off distance, and probability of detection are improved herein by combining a dynamically positioned sliding windowing function with orthogonal feature vectors that include but are not limited to time amplitude decay, spectral composition, and propagation time position in the return signal data.

Abstract: Method and apparatus for improving the detection and discrimination of slow moving or stationary range-Doppler spread objects on or in close proximity to the ground (or sea surface). Invention detects, discriminates and separates radar returns from interference including ground clutter discretes via a coherent process for separating target returns from the myriad of received signals. Thus the method and apparatus improves the probability of detecting and declaring the presence or absence of an object at the same time that the probability of false declaration decreases. The method and apparatus may be applied to the processing of any over resolved object, including airborne radar.

Abstract: A method and apparatus for detecting radar signals in single and multiple (extension) channel wireless network frequencies uses spectral and DC analysis. Spectral images produced through a Fast Fourier transform may be captured and analyzed to determine if any radar signals may be present within the selected wireless network frequencies. A plurality of spectral images may also be analyzed to determine if frequency shifting radar signals are present as well. DC analysis of the power contained at the wireless carrier frequencies may detect radar signals that may be centered near those frequencies.

Abstract: A radar apparatus includes a transmitting antenna and a receiving antenna that has a plurality of antenna elements, and switches the plurality of antenna elements in synchronization with a modulation period to acquire receiving signals. At this time, the antenna elements are switched in accordance with a combination of a first sub-phase and a second sub-phase in which the antenna elements are sequentially switched in opposite directions to thereby acquire the receiving signals. The radar apparatus calculates an azimuth sine value sin ?1 from the acquired receiving signals of the first sub-phase and calculates an azimuth sine value sin ?2 from the receiving signals of the second sub-phase. Next, the radar apparatus calculates an actual azimuth ? through an averaging process of these azimuth sine values sin ?1 and sin ?2.

Abstract: The invention relates to a method, an apparatus and a computer program product for correcting the weather data of radial speed, spectral width and/or differential reflectivity which have been acquired from radar echo data recorded by a ground-based, radar-based remote-sensing appliance (1) for measuring atmospheric conditions and including evaluable weather echoes and interfering ground echoes, corrected weather data being obtained by calculating out the interfering ground echoes from the acquired weather data by using a previously stored clutter map with an intensity distribution of radar echo data which include the ground echoes substantially without weather echoes.

Abstract: A radio detection device includes two or more reception antennas, for detecting a detecting object by a mono-pulse method; the radio detection device including: a variable gain unit for discretely changing respective signal intensity of a difference signal and a sum signal of each reception signal received by the two or more reception antennas; an A/D conversion unit for performing A/D conversion process on the difference signal or the sum signal, the difference signal or the sum signal having the signal intensity changed by the variable gain unit; an angle calculating portion for calculating an angle by the mono-pulse method using the difference signal and the sum signal after the A/D conversion process by the A/D conversion unit; and a control unit for performing a control of individually switching a conversion magnification of the signal intensity by the variable gain unit with respect to the difference signal and the sum signal.

Abstract: A method and system for SNR enhancement in pulse-Doppler coherent target detection for applications in the fields of radar and ultrasound. In accordance with the method of the invention, complex signals are obtained for each of two or more sub-intervals of the time-on-target interval, allowing simultaneous range and Doppler measurements. A coherent integration is the performed on the signals to generate complex-valued folded matrices. The folded matrices are unfolded and target detection is then performed in a process involving one or more of the unfolded matrices. A pulse-Doppler coherent system is also provided configured for target detection by the method of the invention.

Abstract: An orthogonal frequency division multiplexing (OFDM) transmitting apparatus including a signal processing unit, a subcarrier orthogonalization processing unit, and a transmitting unit is provided. The signal processing unit divides a received signal into several real parts and several corresponding imaginary parts. The subcarrier orthogonalization processing unit is coupled to the signal processing unit for receiving the real and the imaginary parts of the signal, and for making the real and the imaginary parts respectively carried by a plurality of different and orthogonal subcarriers. The transmitting unit is coupled to the subcarrier orthogonalization processing unit to transmit the subcarriers.

Abstract: A new approach to radar imaging is described herein, in which radar pulses are transmitted with an uneven sampling scheme and subsequently processed with novel algorithms to produce images of equivalent resolution and quality as standard images produced using standard synthetic aperture radar (SAR) waveforms and processing techniques. The radar data collected with these waveforms can be used to create many other useful products such as moving target indication (MTI) and high resolution terrain information (HRTI). The waveform and the correction algorithms described herein allow the algorithms of these other radar products to take advantage of the quality Doppler resolution.

Abstract: Methods and systems for estimating atmospheric conditions are disclosed according to embodiments of the invention. In one embodiment, a method may include receiving reflective atmospheric data and solving a flow equation for motion coefficients using the reflective atmospheric data. Future atmospheric conditions can be estimated using the motion coefficients and the reflective atmospheric data. In another embodiment of the invention, the flow equation is solved in the frequency domain. Various linear regression tools may be used to solve for the coefficients. In another embodiment of the system, a radar system is disclosed that predicts future atmospheric conditions by solving the spectral flow equation.

Abstract: Methods and apparatus for determining an altitude with an altimeter is provided. One method includes transmitting a signal having a fixed modulation period towards a ground target and then detecting reflected signals off the ground target. The method then implements a single Fast Fourier Transform (FFT) on the detected signals for each modulation period that computes all possible altitudes in real time. A short history of the real time altitude calculations is collected and then the altitude based on the short history of the real time altitude calculations is determined.

Abstract: An acoustic tone at a predetermined frequency is detected after being reflected and modulated by an unknown moving object. Acoustic features are extracted from the reflected acoustic tone using acoustic spectral analysis. A dimensionality of the acoustic features is reduced, and the reduced dimensionality features are statistically classified to identify the object.

Abstract: Techniques to image life forms through obstructions and at long standoff ranges employ a radar system that simultaneously transmits a plurality of RF pulse trains having different transmission frequencies and receives returns of the RF pulse trains reflected from a life form target. The returns are processed to generate digital radar data associated with the transmission frequency of each RF pulse train. The digital radar data is segmented and averaged to generate a Doppler spectrum response associated with the transmission frequency of each RF pulse train. Target classification is performed using the Doppler spectrum responses to extract biometric data describing the life form target.

Abstract: A system and method combine multiple data streams in an efficient and optimal manner, based on new techniques, to determine range, relative angle and velocity with respect to a point of reference. Embodiments of the present invention take advantage of the multiple data streams to provide improved performance when the data is contaminated with environmental and system noise. Embodiments of the present invention may be applied to data output from different target estimation systems, including radar, sonar, ultrasonic and laser systems. In addition, embodiments of the present invention may be implemented in systems with multiple tones and multiple antennas, and generally work in multipath environments.

Abstract: A new approach to radar imaging is described herein, in which radar pulses are transmitted with an uneven sampling scheme and subsequently processed with novel algorithms to produce images of equivalent resolution and quality as standard images produced using standard synthetic aperture radar (SAR) waveform and processing techniques. The radar data collected with these waveforms can be used to create many other useful products such as moving target indication (MTI) and high resolution terrain information (HRTI). The waveform and the correction algorithms described herein allow the algorithms of these other radar products to take advantage of the quality Doppler resolution.

Abstract: A scanning radar system suitable for detecting and monitoring ground-based targets includes a frequency generator, a frequency scanning antenna, and a receiver arranged to process signals received from a target so as to identify a Doppler frequency associated with the target. The frequency generator generates sets of signals, each set having a different characteristic frequency, and includes a digital synthesiser arranged to modulate a continuous wave signal of a given characteristic frequency by a sequence of modulation patterns to generate one set of signals. The frequency scanning antenna cooperates with the frequency generator to transceive radiation over a region having an angular extent dependent on the generated frequencies.

Abstract: A system and method for filtering clutter is contemplated that in one aspect performs clutter-filtering on complex-voltages. In one aspect, spectral coefficients identified from a series of spectral coefficients as having been affected by clutter are replaced by a refilling procedure to maintain the statistical properties of the spectral coefficients that are unaffected by clutter. Dual-polarization radar variables that have phase dependence can be subsequently generated from the modified spectral data.

Abstract: In a FM-CW or CW radar apparatus, when interference components are contained in channel signals obtained as beat signals from array antenna elements of respective channels, and the interference components result from directly receiving transmitted CW radar waves from an external source, phase shifting is applied to each of the channel signals to shift respective phases of the interference components of the respective channels to a condition corresponding to reception of interference waves from a predetermined direction. The interference components are then eliminated, and reverse phase shifting is applied to restore remaining components of the channel signals to their original phase condition.

Abstract: The present invention is a method of finding range and velocity of a target in a radar system using a time scale factor. Specifically, sending at least one signal from at least one transmitter to a target. A return signal is then received from the target at each transmitter and the elapsed time is recorded. The range to the target and velocity of the target are calculated based on a time scale factor of the recorded elapsed times. These values are appropriately output to the user.

Abstract: An instantaneous frequency measurement (IFM) receiver includes a receiver module for determining a frequency fe of a received signal. Also included is a discrete Fourier transform (DFT) module configured to sum values of digital samples of data in a block of data, wherein the values of the digital samples of data are based on the frequency fe. A confirmation module confirms the frequency fe, if the sum has a value greater than a predetermined threshold. The DFT module is configured to obtain the sum of N-sample points of data which are disposed in the block of data by using a DFT kernel function.

Abstract: Method and apparatus for analyzing a substance in a container, the method comprising the steps of: disposing antenna means (3) at a predetermined geometrical distance (L) from a container portion (13); transmitting a signal from said antenna means through a surface portion (12) of the substance towards said container portion; receiving a first reflected signal in said antenna means from said container portion; determining a geometrical distance (L1) from the surface portion to the container portion; varying the frequency of the transmitted signal to determine a first phase displacement between the transmitted signal and the first reflected signal; determining an optical distance from the surface portion to the container portion based on the first phase displacement; and determining the index of refraction (nt) of said substance based on the optical and geometrical from the surface portion to the container portion.

Abstract: A computer implemented method, apparatus, and computer usable program code for focusing an image. In one advantageous embodiment, a method is used to focus an image. Optimization is performed to identify an array of coefficients for a polynomial representing a phase correction in a manner that minimizes an entropy value generated by an entropy calculation for the image. The array of coefficients is applied to the polynomial to obtain a desired phase correction. A phase error in the image is corrected using the desired phase correction to focus the image.

Abstract: Provided is a high resolution distance ranging apparatus using an ultra-wideband (UWB) communication. The apparatus includes: a first spectrum analyzer for extracting a frequency component corresponding to multipath time delay from a reception signal; a second spectrum analyzer for acquiring a noise subspace of the extracted frequency component and extracting a frequency component where maximum power is located from a frequency spectrum based on the noise subspace; a time of arrival (TOA) extractor for extracting TOA based on the frequency component where maximum power is located.

Abstract: A target object detection apparatus periodically executes a transmit/receive operation to transmit radar waves and obtain received signals from resultant incident reflected waves from respective target objects. An individual correlation matrix of received signal values is derived for each one of a fixed plurality of successive transmit/receive operations, with the transmission frequency being changed at successive operations. Individual correlation matrices derived from respective transmit/receive operations are time-averaged to obtain an average correlation matrix for use in obtaining target object information such as direction or velocity, with effects of correlation between respective incident waves being suppressed.

Abstract: A receiver, such as a miniaturized microwave-photonic coherent receiver (MMPR) is disclosed. The receiver includes an antenna to output an electrical RF signal received on a section of the antenna, a laser to produce an optical signal, a photonic modulator to receive the optical signal and the electrical RF signal and produce an EO-RF signal and to receive the optical signal and an electrical LO signal and produce an EO-LO signal, a signal combiner to provide a combined EO-RF and EO-LO signal and a photodiode to receive the combined signal and produce an IF signal. A method of detecting an object using the MMPR includes receiving an electrical RF signal corresponding to the object, outputting the electrical RF signal to a photonic modulator, modulating the electrical RF signal onto an optical carrier, demodulating the electrical RF signal to produce an IF signal and processing the IF signal.

Abstract: In a radar device including a transmitting unit for transmitting a transmission signal having plural modulation sections, a receiving unit for receiving a reflection signal obtained through reflection of the transmission signal from a target by an array antenna having plural channels, a mixing unit for mixing the transmission signal with reception signals of the plural channels to obtain beat signals of the plural channels, a frequency analyzing unit for frequency-analyzing the beat signals of the plural channels, and a direction calculating unit for calculating the direction to the target on the basis of frequency analysis results of the plural channels, the direction calculating unit adds correlation matrixes generated from peak frequency spectra of the plural modulation sections to obtain an summed correlation matrix, and calculating the direction to the target on the basis of the summed correlation matrix.

Abstract: The encoder transforms the audio signals (x(n),y(n)) from the time domain to audio signal (X(k),Y(k)) in the frequency domain, and determines the cross-correlation function (Ri, Pi) in the frequency domain. A complex coherence value (Qi) is calculated by summing the (complex) cross-correlation function values (Ri, Pi) in the frequency domain. The inter-channel phase difference (IPDi) is estimated by the argument of the complex coherence value (Qi), and the inter-channel coherence (ICi) is estimated by the absolute value of the complex coherence value (Qi).

Abstract: Provided is a non-statistical method for compressing and decompressing complex SAR data derived from reflected energy. The method includes selecting a first FFT to provide a target ratio of pixel spacing to resolution. A second FFT is then selected which is smaller than the first FFT. The data is zero-padded to fill the second FFT and transformed to provide at least one transfer frequency. This transfer frequency is then transferred to the at least one remote site. At the remote site the second FFT is inverted to restore the data from the received transfer frequency. The restored data is then zero-padded again to fill the first FFT. The first FFT is then used to transform the zero-padded restored data to provide a data set of points with the target ratio of pixel spacing to resolution.

Abstract: A traffic radar utilizes digital signal processing (DSP) to determine targets based on signal strength histories. From these histories, a target vehicle having the strongest Doppler return signal is identified and its speed is displayed, and a target vehicle having the highest frequency return signal is identified and its speed is displayed. The traffic radar may also display the relative strength of the strongest return signal and the relative strength of the highest frequency return signal, thereby showing a comparison of the strengths of the return signals from the target vehicles.

Abstract: A synthetic aperture radar to provide high resolution in the azimuth direction under the predetermined conditions of wide observation swathwidth in the range direction, stripmap observation and free PRF (Pulse Repetition Frequency) comprises a transmission antenna 102 for a single system and receiving antennae 104a, 104b for two systems. The beam width in the azimuth direction of a transmission beam 103 from the transmission antenna 102 is set equal to twice as wide as the beam width of each of the receiving antennae 104a, 104b. Moreover, a receiving antenna beam 105a is directed to the moving direction, while the other receiving antenna beam 105b is directed to opposite to the moving direction. The transmission antenna 102 and the receiving antennae 104a, 104b for two systems are used in common by dividing a single array antenna in the elevation direction to configure the receiving antennae 104a, 104b.

Abstract: A radar target detection method in which an azimuth at which a target is located is detected on the basis of reception signals obtained through antenna elements of an array antenna by detecting a change in levels of spectrum peaks in an azimuth spectrum of reception signal intensities, calculating a level of correlation between the level change of each spectrum peak and a directivity pattern of the array antenna in an azimuth range corresponding to the spectrum peak, and determining an azimuth corresponding to one of the spectrum peaks having the highest corresponding correlation level to be the azimuth at which the target is located.

Abstract: An electronic scanning radar apparatus has a cutting portion for cutting receiving data which is comprised of N numbers of data for each channel into two more short time data having M (<N) numbers of data in a time direction for each channel, an inverse matrix estimator for computing and estimating an inverse matrix of the time series correlation matrix from the short time data, and a phase information producing portion for computing CAPON phase information out of the estimated inverse matrix of the time series correlation matrix in order to detect a distance, an azimuth and a relative speed of a target on the basis of a computed CAPON phase information.

Abstract: A radar apparatus includes a sending unit for sending a transmission wave, a plurality of receiving parts for receiving a reflected wave from a reflecting object in a parallel manner, beat signal generation parts for acquiring beat signals at the receiving parts, respectively, from the transmission wave and the wave received at the receiving parts, a beat signal processing part for individually processing the beat signals of the receiving parts, a DBF processing part for DBF processing a beat signal processing result, and an object detection part for acquiring information on the reflecting object from frequency components of a DBF processing result or the beat signal processing result. Amounts of phase lag of the receiving parts are set to different values. The beat signal processing part includes a phase correction part that corrects the phase lag amounts corresponding to the individual receiving parts so as to make them equal to one another.

Abstract: One preferred embodiment of the present invention provides a system and method for suppressing motion interference in a radar detection system. Briefly described, in architecture, one embodiment of the system, among others, can be implemented as follows. The system includes a signal generator that transmits microwave signals toward a target area. Also, the system includes a data control system to collect data from reflected microwave signals from the target area and to analyze the data in order to suppress unwanted motion interference generated by movement of the radar detection system. Other systems and methods are also provided.

Abstract: A radar system transmits a beam of detection radio waves with a predetermined azimuth width, receives a reflected wave from a target, changes a central azimuth of the beam, and detects the distribution of reception signal strengths at predetermined angular intervals and for each predetermined distance. Then, when the reception signal strength distribution associated with changes in azimuth is expressed in rectangular coordinates, an azimuth corresponding to a vertex of an isosceles triangle that approximates the reception signal strength distribution and has an azimuth width, which is determined by the beam azimuth width, as its base is detected as the central azimuth of the target.

Abstract: There is provided a radar system for detection of one or more objects. The radar system comprises a radar wave transmitter for simultaneously transmitting a CW radar signal and a FM-CW or MF radar signal, and a first radar wave receiver for receiving CW and FM-CW or MF radar signals, reflected from one or more objects present in a detection range of the radar system. The system may further comprise a first CW mixer for mixing CW transmission signals and reflected CW signals received by the first receiver, and a first FM-CW or MF mixer for mixing FM-CW or MF transmission signals and corresponding reflected FM-CW or MF signals received by the first receiver.

Abstract: A target detecting apparatus mounted on a vehicle has an electronically agile radar detecting a beat signal indicating a difference in frequency between transmission and reception signals and producing a time series of N reception data from the beat signal, a determining unit determining search areas placed at different ranges of distance from the vehicle while considering a running state of the vehicle and determining a data length for each search area, an extracting unit extracting (N?M+1) time series of short time data, respectively, having the data length corresponding to M reception data from the N reception data for each search area, a producing unit producing phase information from the short time data for each search area, and a detecting unit determining a target distance and a target bearing from the phase information and detecting a target from the target distance and the target bearing.

Abstract: A millimeter wave image processor, capable of performing imaging by matching and filtering while considering a spherical wave on an antenna face in a near field, is provided. The processor includes: a T-antenna which receives a radio wave emitted by a target; an A/D converter which A/D converts signals received by the T-antenna; a correlation processing unit which performs correlation processing to a combination of signals of a horizontal conversion output and a vertical conversion output among A/D converted data; and an imaging processor which correlates a reference function in which a received signal is generated theoretically on an assumption that the target is at a position of a focused distance and a received signal of a spherical wave received by the T-antenna for each pixel in the field of view to thereby create an image of the target.

Abstract: A data processor applies transform processing to a first group of samples at a primary sampling rate, where the first group of samples is within a data window associated with at least one of the data blocks. A detector detects an estimated frequency shift between the transmitted signal and the reflected signal based on a primary peak frequency determined by the transform processing at the primary sampling rate. The data processor applies transform processing to a second group of samples at a secondary sampling rate, where the data window contains previously read samples and at least one new sample, if the estimated frequency shift falls within a target response frequency band. The detector detects an observed frequency shift between the transmitted signal and the reflected signal based on a secondary peak frequency determined by the transform processing at the secondary sampling rate.

Abstract: Communication between a remote locator and a transponder is used to determine the relative position of the transponder. The transponder and locator each include a transmitter and a receiver. The locator transmits an inquiry in the form of a relatively powerful cyclically encoded signal with repetitive elements, uniquely associated with a target transponder. Periodically, each transponder correlates its coded ID against a possible inquiry signal, determining frequency, phase and framing in the process. Upon a match, the transponder transmits a synthesized response coherent with the received signal. The locator integrates multiple cyclical response elements, allowing low-power transmissions from the transponder. The locator correlates the integrated response, determines round-trip Doppler shift, time-of-flight, and then computes the distance and angle to the transponder. The transponder can be wearable, bionically implanted, or attached to, or embedded in, some object.

Abstract: A radar device (100) comprising transmit and receive parts, and a control unit (CU). The transmit part includes means (WG) for generating a signal within a certain band, and the receive part comprises a filter (AAF), an AD-converter (ADC) and a Fourier transform unit (FFT1). The transmit part generates a group of signals, each having a first bandwidth between a first and a second frequency, in such a way that a larger bandwidth (B1-B4) is covered by the group. The receive part is open over said larger bandwidth (B1-B4) during reception of each signal in said group, and the transmit part comprises means (PAD, FFT2) for creating FFT-copies of the received signals and means (CONJ) for creating conjugates of said copies. The receive and transmit parts comprise means (EXTR) for extracting data from the FFT from the first bandwidth covered by a received signal, and the radar device comprises means (DIFF) for correlating said extracted FFT-data.

Abstract: A target object motion estimation method using at least one subset of a complex SAR image. Coarse range cell alignment is performed on at least one subset of a complex SAR image. At least one subset is autofocused, thereby providing an estimated phase error function. The estimated phase error function yielded by autofocusing (or a manipulated version of the phase error function) may be analyzed to detect, characterize, and estimate target object motion.

Abstract: Channel quality can be detected accurately in a wireless transmission system such as an HSDPA method. In the case of estimating a channel quality of a signal transmitted by a Code Division Multiple Access method and of estimating the channel quality in a system having a synchronization channel not orthogonal to a channel receiving data, a noise component of a desired channel is estimated; degree of a noise component caused by the synchronization channel is estimated with respect to the estimated noise; and a channel quality of a receiving channel is detected based on the estimated degree of the noise component.

Abstract: A computer system for compressing synthetic aperture radar (SAR) images includes a database for storing SAR images to be compressed, and a processor for compressing a SAR image from the database. The compressing includes applying an anisotropic diffusion algorithm to the SAR image, and compressing the SAR image after applying the anisotropic diffusion algorithm thereto. Applying the anisotropic diffusion algorithm includes determining noise in the SAR, selecting a noise threshold for the SAR image based on the determined noise, and mathematically adjusting the anisotropic diffusion algorithm based on the selected noise threshold.

Abstract: Providing multi-spot inverse synthetic aperture radar (ISAR) imagery is disclosed. Embodiments of techniques in accordance with the present disclosure may advantageously improve multiple target discrimination, detection, identification, and tracking using ISAR imaging. In an embodiment, an inverse synthetic aperture radar (ISAR) method for producing multiple ISAR images from a single waveform includes transmitting a chirp signal into a dwell surveyed by the antenna beamwidth. Multiple dechirp reference signals may be generated to demodulate return signals from the dwell at multiple selected intervals within a pulse repetition interval (PRI) to create demodulated signals.

Abstract: Systems and methods that adapt to the weather and clutter in a weather radar signal and apply a frequency domain approach that uses a Gaussian clutter model to remove ground clutter over a variable number of spectral components that is dependent on the assumed clutter width, signal power, Nyquist interval and number of samples. A Gaussian weather model is used to iteratively interpolate over the components that have been removed, if any, thus restoring any overlapped weather spectrum with minimal bias caused by the clutter filter. The system uses a DFT approach. In one embodiment, the process is first performed with a Hamming window and then, based on the outcome, the Hamming results are kept or a portion of the process is repeated with a different window. Thus, proper windows are utilized to minimize the negative impact of more aggressive windows.

Abstract: The portion corresponding to a main bang signal leaking from a transmission/reception switching unit is extracted as a frequency estimation signal from an IF signal from a mixer in a signal extracting unit, a frequency is estimated in a frequency estimating unit, and the frequency of a local oscillation signal of a local oscillator is controlled so that the frequency of the IF signal is equal to a target value. The frequency estimation in the frequency estimating unit is carried out by using Discrete Fourier Transform or Fast Fourier Transform.