263 results about "Radar waveforms" patented technology

Methods and apparatus are presented which reduce the overall cost and increase the imaging capability for medium and long range automotive radar sensing applications through the combination of a high signal-to-noise ratio and wide dynamic range radar waveform and architecture, antenna arrangement, and a low cost packaging and interconnection method. In accordance with aspects of the present invention, one way a high signal-to-noise ratio and wide dynamic range imaging radar with reduced cost can be achieved is through the combination of a pulsed stepped-frequency-continuous-wave waveform and electrically beam-switched radar architecture, utilizing a planar package containing high-frequency integrated circuits as well as integrated high-frequency waveguide coupling ports, coupled to a multi-beam waveguide-fed twist-reflector narrow beam-width antenna. Other methods and apparatus are presented.

Method and apparatus for developing radar scene and target profiles based on Compressive Sensing concept. An outgoing radar waveform is transmitted in the direction of a radar target and the radar reflectivity profile is recovered from the received radar wave sequence using a compressible or sparse representation of the radar reflectivity profile in combination with knowledge of the outgoing wave form. In an exemplary embodiment the outgoing waveform is a pseudo noise sequence or a linear FM waveform.

A method for processing received radar returns of a radiated wide-band arbitrary waveform in a wide-band radar processing system using spectral processing. The received wide-band radar returns are undersampled by using a first sampling rate to obtain an undersampled digital wide-band radar waveform. Spectral processing is performed on the power spectrum of the undersampled digital wide-band radar waveform in order to obtain a discrete ripple frequency power spectrum of the undersampled digital wide-band radar waveform. Ripple frequencies indicating radar targets are located in the discrete ripple frequency power spectrum of the undersampled digital wide-band radar waveform. A radar receiver, a digital wide-band radar processing system and a computer program product.

An automotive radar system is disclosed that comprises an interference classifier 203 for determining a type of interference in a signal received from a multiuser environment. A sweep pattern comprising frequency sweep signals for a transmitted radar waveform is then advantageously determined in dependence upon the level of interference experienced by frequency sweep signals for the determined type of interference. The automated radar system comprises: a receiver 102 operable to receive a noise signal comprising burst noise, frequency chirp signals generated by one or more other users, or a combination thereof; a signal generator 109, 110 operable to generate a plurality of different frequency sweep signals; a signal combiner 104 operable to combine each frequency sweep signal with a received noise signal to generate a combined signal for each frequency sweep signal; an interference classifier 203 operable to identify combined signals corresponding to received noise signals comprising frequency chirp signals and to determine the noise levels of said combined signals corresponding to received noise signals comprising frequency chirp signals; and a selector 206 operable to select a plurality of frequency sweep signals in dependence upon the noise level determinations by the interference classifier 203 on the combined signals corresponding to received noise signals comprising frequency chirp signals; and a control unit 206 operable to determine a sweep pattern comprising the selected plurality of frequency sweep signals to be transmitted as an output radar waveform.

An automotive radar system to determine a sweep pattern to be transmitted as an output radar waveform in a multiuser transmission environment is disclosed. The system includes: a receiver to receive noise signals; a signal generator to generate a plurality of different frequency sweep signals; a signal combiner to combine each frequency sweep signal with a received noise signal; an interference classifier to identify combined signals corresponding to one or more received noise signals including frequency chirp signals and to determine the respective noise levels of the identified combined signals corresponding to one or more received noise signals including frequency chirp signals; a selector to select a plurality of frequency sweep signals in dependence upon the noise levels determined by the interference classifier; and a control unit to determine a sweep pattern comprising the selected plurality of frequency sweep signals to be transmitted as an output radar waveform.

The invention relates to a method for designing a multiple-input-multiple-output synthetic aperture radar (MIMOSAR) system on the basis of sub-band synthesis. The method includes the steps that a radar waveform generating module generates quadrature encoding signals needed for transmission of various transmitting array elements; according to radar, M transmitting array elements are used for transmitting signals at the same time, and N receiving array elements are used for receiving echo signals simultaneously; each receiving array element receives the echo signals through a main reception channel, extracts a part of the echo signals as required from the echo signals received by the main reception channel through minor reception channels and is provided with the M minor reception channels; signal reconstruction is carried out on the part of the echo signals obtained by the M minor reception channels of each receiving array element; sub-band synthesis is conducted on the reconstructed signals in a distance. The orientation multi-aperture MIMOSAR system based on a sub-pulse linear frequency modulation stepping system namely sub-band synthesis is adopted, the instantaneous operation bandwidth and sampling rate of the MIMOSAR system are reduced manyfold, and remote high-resolution wide-observation-band imaging can be achieved in an SAR mode.

A multiple-input-multiple-output radar waveform design method belongs to the radar communication technical field, and aims to provide a design method with lower related sidelobe and frequency spectrum inhibition depth, high efficiency, less consumption, high robustness, and excellent time frequency anti-interference performance; the method comprises the following steps: pre-evaluating an autocorrelation sidelobe inhibition fuzzy region according to a relative position between a strong scatterer and a to be measured object in a radar scene, thus forming a corresponding object function; analyzing MIMO radar waveform orthogonality constraint so as to form the object function satisfying the orthogonality constraint; pre-evaluating a frequency domain interference fuzzy frequency band zone according to scene prior information, thus forming the corresponding object function; forming a constant modulus phase coding waveform constrained condition; forming a loose alternative projection algorithm framework; solving a waveform design according to the loose alternative projection algorithm framework, thus providing three waveform optimization output modes. The loose alternative projection constant modulus waveform coding design enables the MIMO radar to have batter detection performance.

The invention provides an active and passive radar cooperative anti-interference method based on a waveform design, belongs to the technical field of radar anti-interference, and particularly relates to a radar waveform design technology. According to the active and passive radar cooperative anti-interference method, an active and passive radar cooperative work mode is adopted, interference is detected and identified through echo information detected by a passive radar in real time, relevant parameters of the interference are estimated, an active radar uses interference information provided by the passive radar to design the optimal transmission waveform and process the echo information, and therefore the active and passive radar cooperative anti-interference method has the advantages of being small in calculation amount and high in real-time performance, and improving anti-interference capacity of the radars in complex electromagnetic interference environments.

Method and apparatus for developing radar scene and target profiles based on Compressive Sensing concept. An outgoing radar waveform is transmitted in the direction of a radar target and the radar reflectivity profile is recovered from the received radar wave sequence using a compressible or sparse representation of the radar reflectivity profile in combination with knowledge of the outgoing wave form. In an exemplary embodiment the outgoing waveform is a pseudo noise sequence or a linear FM waveform.

The invention discloses a waveform optimization method based on target cognition and transmitted power distribution, which mainly solves the problem that the current waveform optimization algorithm is not suitable for a broadband radar. The method comprises the following steps of: (1) building a waveform-optimized signal model of a cognitive radar of a broadband; (2) utilizing a single echo to estimate the power spectral density of a target; (3) calculating the transmitted power of a transmit signal being a linear frequency modulation signal to be used as a constrained initial value of the transmitted power; (4) constructing a cost function; (5) solving the cost function; (6) optimally setting the power spectral density of transmitted waveform corresponding to the transmitted power; (7) calculating the related coefficient of the estimated value and the true value of the power spectral density of the target corresponding to the optimized waveform; (8) and judging and outputting the power spectral density of the transmitted power and the transmitted waveform according to whether the related coefficient meets the requirements. According to the method, the transmitted waveform optimization and power distribution of a cognitive radar system of the broadband can be realized, and the efficiency and overall performance of the system are increased.

A radar system is disclosed, which comprises an orthogonal frequency division multiplexing (OFDM) modem and a frequency scanning antenna. In transmit, the OFDM modem modulates radar waveforms and the frequency scanning antenna radiates the OFDM modulated radio frequency (RF) energy. In receive mode, the frequency scanning antenna captures the echoes and the OFDM modem demodulates the echoes. Directionality of the frequency scanning antenna is dependent upon RF carrier frequency. In other features, the radar system further comprises a transmit / receive (T / R) module that up-converts and amplifies the OFDM modulation, and outputs the amplified signal to the frequency scanning antenna. The T / R module amplifies and down-converts a received RF echo from the frequency scanning antenna and outputs the down-converted echo to the OFDM modem. A plurality of scanning angles are measured simultaneously.

A method and apparatus for selecting frequency modulated continuous wave waveform parameters for multiple radar coexistence by a user equipment is described. The user equipment may transmit a radar waveform consisting of a number of chirps, with each chirp having a same duration. The user equipment may vary waveform parameters of the radar waveform for at least a subset of the number of chirp, where the waveform parameters may be chosen from a codebook comprising at least one codeword of parameters. Reflected radar waveforms are received and processed where the processing includes applying a fast time discrete Fourier transform to reflected radar waveforms to produce a one dimension peak in a time delay dimension for each reflected waveform; and applying a slow time discrete Fourier transform to the reflected radar waveforms, where peaks for the reflected waveforms are added.

The invention discloses a centralized MIMO (Multiple Input Multiple Output) radar waveform designing method based on receiving wave beam formation and mainly solves the problem that the existing method is incapable of reducing a receiving echo distance sidelobe and an angle sidelobe of the centralized MIMO radar. The Centralized MIMO radar waveform designing method comprises the following steps: (1), determining the number of antennas, the number of waveforms and lengths of code elements of the centralized MIMO radar according to an actual radar system and requirement; (2), determining a detection angle and an inhibition angle according to radar detection requirement and normalizing the detection angle and the inhibition angle; (3), determining an expected sending direction map according to the detection angle; (4), building a target function and constraint conditions for optimizing the MIMO radar waveform; and (5), obtaining the MIMO radar waveform by an optimization algorithm according to the built target function and the constraint conditions. The centralized MIMO radar waveform designing method is capable of reducing the receiving echo distance sidelobe and the angle sidelobe of the centralized MIMO radar and can be used for designing the waveform of the centralized MIMO radar.

The invention relates to a multi-frequency multi-base high-frequency ground wave radar system and an operating method thereof. The multi-frequency multi-base high-frequency ground wave radar system comprises an analog extension, a digital extension, an ultra-high-stability time frequency standard device, a power amplifier, a transmitting antenna, a receiving antenna and a GPS (global position system) antenna. The analog extension comprises a frequency synthesizer, an analog amplification filtering component, an analog frequency multiplier and a multi-channel analog receiving front end, and the digital extension comprises a multi-channel data acquisition and processing board card, a synchronization control board card and an industrial control computer. The frequency synthesizer adopts a digital up-conversion scheme; the analog receiving front end adopts a multi-stage broadband program-controlled tracking and filtering scheme with no need for frequency mixing; data acquisition adopts a radio-frequency direct sampling and digital down-conversion scheme; and the time frequency standard is provided by a GPS tame low-phase-noise and ultra-high-stability crystal oscillator. The multi-frequency multi-base high-frequency ground wave radar system has the following advantages that the all-digital transmission and reception technology is adopted, and the system has good universality and scalability; and the radar waveform and time sequence are flexible and controllable, and the time-sharing, multi-frequency and single-base or multi-base detection can be realized.

A method and apparatus for cognitive non-linear radar processing comprising identifying one or more frequency bands of interest, passively scanning, using a non-linear radar (NR), the one or more frequency bands of interest to determine whether interference signals are occupying the one or more bands, transmitting radar waveforms and receiving radar waveform responses at one or more frequency bands determined to be free of interference, determining a likelihood of a target being present or not based on whether the received waveform responses match stored waveform responses for non-linear targets, and modifying waveform parameters of the transmitted radar waveform when the received waveform responses match the stored waveform responses, so as to transmit a modified radar waveform.

Certain embodiments provide a network waveform system that can include multiple radars disposed at different geographical positions within an environment. The multiple radars may be configured to transmit a network waveform. The network waveform may include multiple radar waveforms. Each radar waveform of the multiple waveforms may be transmitted by a specific radar of the multiple radars. The system can also include a computer system coupled with the multiple radars that can include a processor and a memory. The memory may be configured to store information including data received from the multiple radars, data processed by the processor, and processing code executable by the processor. The processing code may include instructions to receive output data from the multiple radars resulting from the transmitted network waveform instructions to jointly process the output data from the multiple radars to determine a measurement of the environment based on the network waveform.

Certain embodiments provide a network waveform system that can include multiple radars disposed at different geographical positions within an environment. The multiple radars may be configured to transmit a network waveform. The network waveform may include multiple radar waveforms. Each radar waveform of the multiple waveforms may be transmitted by a specific radar of the multiple radars. The system can also include a computer system coupled with the multiple radars that can include a processor and a memory. The memory may be configured to store information including data received from the multiple radars, data processed by the processor, and processing code executable by the processor. The processing code may include instructions to receive output data from the multiple radars resulting from the transmitted network waveform instructions to jointly process the output data from the multiple radars to determine a measurement of the environment based on the network waveform.

The invention discloses a multi-input multi-output radar waveform design and processing method, specifically comprising the following steps: setting waveform parameters according to the resolution power of radar and the zero side lobe band request, and forming a multi-phase sequence matrix; forming the multi-phase encoding sequences of various transmission waveforms by using various lines orderly connected with each other in series in the multi-phase sequence matrix; using the multi-phase encoding sequences connected in series to respectively perform encoding modulation for the base pulse to generate the transmission signals of various transmission array elements of the transmission array; transmitting the generated transmission signals by various transmission array elements; receiving the echo signals of the transmission signals reflected by the target object through the receiving array elements of the receiving array; performing base band conversion and A / D conversion for the echo signals; regarding the transmission signal as the reference signal, and performing pulse compression processing for the echo sequence of various receiving array elements from the frequency domain; and using the scheduled range gate to intercept the pulse pressure output echo sequence according to the stated time interval to limit the interference of the side lobe. The application of the waveform processing method can fully eliminate the interference of the correlative side lobes with different transmission waves in the multi-input multi-output radar pulse compression output signal sequence in the range of the stated distance so that the precise separation for the target scattering information in different observation channels can be realized so as to improve the precision of the following radar signal and data processing.

Certain aspects provide a method for radar detection by an apparatus. The method generally includes transmitting a radar waveform in sets of transmission time intervals (TTIs), using a common set of radar transmission parameters in each set of TTIs, to perform detection of a target object, varying at least one of the common set of radar transmission parameters between sets of TTIs, and identifying interfering signals based on observed changes in monitored parameters of received signals across sets of TTIs due to the varying.

A method and apparatus is operative for multiple target detection in a radar system which employs a radar waveform of two or more frequency diverse subpulses. The apparatus adds coherent processing of the subpulse echo signals to determine the presence of multiple scattering centers within the radar resolution cell. The subpulses are coherently combined and one can then estimate the number of scattering centers by forming a sample covariance matrix between the subpulse frequency channels and then performing an Eigenvalue decomposition. The resulting Eigenvalues represent the signal strengths of the scattering centers when the associated Eigenvectors correspond to the optimal subpulse weights associated with that signal. A single strong Eigenvalue indicates a single target while two or more strong Eigenvalues or those Eigenvalues larger than the noise related Eigenvalues or a threshold, indicates the presence of multiple targets.

The invention provides a three-dimensional laser etch decomposing algorithm based on the combination of particle swarm optimization and LM algorithm (Levenberg-Marquardt Algorithm). The method comprises the steps of smoothly denoising; detecting the peak value; decomposing the waveform; fitting. According to the method, the threshold is set and the threshold is detected, so as to determine the quantity of smoothly denoised wave with good signal-to-noise ratio; the particle swarm optimization is performed to acquire the rough strength parameter value and the rough wide parameter value of single waveform to be used as the initial values of the LM algorithm to improve the decomposing precision as well as reducing the error influence of the initial value.

The invention discloses an optimal design method of a missile-borne MIMO (Multiple-Input Multiple-Output) radar waveform covariance matrix. The main idea comprises the steps of determining missile-borne MIMO radar, wherein there is a target and clutter within a detection range of the missile-borne MIMO radar; recording echo signals received by the missile-borne MIMO radar when detecting the targetto be echo signals received by the missile-borne MIMO radar in a clutter environment, wherein the echo signals received by the missile-borne MIMO radar in the clutter environment comprise target signal, clutter signals and noise signals, and determining a transmitted waveform vector s of the missile-borne MIMO radar; setting a linear filter weight vector, and calculating to acquire a joint optimization problem of the transmitted waveform vector of the missile-borne MIMO radar and the linear filter weight vector in the clutter environment according to the transmitted waveform vector s; and acquiring an optimal design result of the missile-borne MIMO radar covariance matrix according to the joint optimization problem of the transmitted waveform vector of the missile-borne MIMO radar and thelinear filter weight vector in the clutter environment.

The invention discloses a laser altimeter vertical control point generating method in combination with a stereopair. The method comprises the steps that dense elevation point cloud data is obtained through a stereo camera; then point cloud data within a footprint is classified according to elevations, and the surface feature classification number at different elevations within a light spot is obtained; finally, large-spot laser radar waveform decomposition is guided through the classification number, and a generalized vertical control point is obtained. The aim of cooperative mapping of the stereo camera and satellite-borne laser radar is achieved, the result of three-dimensional positioning of a laser altimeter is combined with the mapping result of the stereo camera, and automatic extraction of the generalized vertical control point is achieved.

The invention relates to a poly-phase code radar signal waveform automatic identification method based on continuous wave Doppler (CWD) feature and belongs to the technical field of information countermeasures. According to the poly-phase code radar signal waveform automatic identification method based on CWD feature, a discrete sampling type Choi-Williams conversion is used as a basic tool, a CWD image of poly-phase code pulse compression radar signal is used as a feature extraction object, a Pseudo-Zernike moment of the CWD image, a target number of an image, a time position of a peak power in a CWD and a poly-phase code waveform symmetrical property are taken as features to identify a poly-phase code pulse compression radar waveform, and a neural network which is composed of 10 perceptrons and stops in advance of overall average is set up for automatic waveform identification. The poly-phase code radar signal waveform automatic identification method based on CWD feature has the advantages that the identification precision of the poly-phase code radar signal waveform is improved, the requirement of a signal to noise ratio is further decreased, and a new way can be developed for the design of radar signal identification and sorting by popularized and used in a poly-phase code continuous wave radar signal.

The invention discloses a C-waveband frequency comprehensive generator with low phase noise and wide frequency agility. The generator comprises a 100 MHz of constant-temperature crystal oscillator, a power divider, a frequency tripler, a P-waveband phase locked loop, a C-waveband sampling phase locked medium oscillator, a mixer, a filter, a programmable logic device, a digital frequency direct synthesizer and a frequency divider. The generator disclosed by the invention has the characteristics that: the digital frequency synthesizer (DDS) is rationally utilized; the radar emission waveform iseasy to generate; the digital phase locked circuit is simple; the frequency change is convenient; the remote end of the sampling phase locked medium oscillator has excellent phase noise; the shortcomings are mutually made up; the circuit structure is simple; the phase noise is good; the radar waveform is convenient to change; furthermore, the frequency agility is rapid to carry out.

The present invention discloses a method for performing adaptive variable waveform switching to track a target. The invention aims to provide a target tracking method which is short in echo receiving period, high in scanning time resource utilization rate and is capable of increasing radar detection distances. The realization process of the method of the invention includes the following steps that: on the basis of a distance detection range R required by a radar and an allowable transmitter duty ratio D, the detection range R required by the radar is divided into N segments, and adjacent distance segments are overlapped; the allowable maximum scanning time of each segment is calculated according to the maximum distance, beam width, wavelength, target speed and target acceleration of each distance segment; a pulse width and a radar pulse repetition frequency corresponding to each segment are calculated; the allowable maximum scanning time of each segment is calculated; and phase-coherent accumulation pulse counts corresponding to each distance segment is determined according to the maximum scanning time, and radar waveform parameters according to which corresponding pulse widths and radar pulse repetition frequencies change correspondingly when required distance coverage changes with the target during a period when the target flies from the distant to the near or from the near to the distant are also determined.

The invention discloses a laser radar waveform time discriminating method and an online distance measuring system, wherein online waveform processing of a laser radar signal and real-time distance measuring are realized. The method comprises the steps of acquiring a pulse signal which is output from a detecting and receiving unit by a laser radar high-speed acquiring and processing unit, determining a target function and a fitting parameter vector by a programmable processor of the high-speed acquiring and processing unit through a waveform characteristic, determining a signal effective rangeand realizing waveform cutting, performing online calculation of an initial fitting target function based on the cut waveform, performing real-time calculation of an error between the initial fittingtarget function and the acquired signal for determining a residual error vector, performing parallel calculation on a residual error vector partial derivative and determining a Jacobian matrix; determining an optimal condition of the residual error vector based on the Jacobian matrix, and performing online calculation of a final fitting target function; determining a pulse time based on an onlinefitting parameter vector, calculating a target distance, combining distance measuring data and waveform data, and uploading the combined data to an upper computer for displaying and storage. The laserradar waveform time discriminating method and the online distance measuring system can realize online waveform parameter vector extraction, distance resolving and point cloud generation.

A method and apparatus for determining three dimensional sub-voxel positions using synthetic aperture radar. The apparatus includes at least four non-coplanar, phase-coherent synthetic aperture radar (SAR) platforms comprising a plurality of phase-synchronized local oscillators cohered to a common reference clock, a first SAR platform of the SAR platforms operable to transmit a radar waveform, and the SAR platforms operable to receive scattered energy waveforms resulting from the radar waveform and operable to generate two-dimensional (2-D) SAR images based on the received scattered energy waveforms. The apparatus also includes a synchronizing processor operable to communicate with the SAR platforms and operable to synchronize a plurality of SAR transmission and receiving intervals for the SAR platforms. Optionally, the apparatus also includes an image-coregistration processor operable to receive at least four 2-D SAR images from the SAR platforms, and operable to generate a 3-D SAR image having 3-D voxel positions by coregistering the 2-D SAR images. Optionally, the apparatus also includes a sub-voxel position processor operable to calculate sub-voxel positions of single point scatterers from differential phase measurements on a given voxel across all of the SAR platforms.