284 results about "Passive radar" patented technology

According to the invention, IEEE 802.15.4a packets are used for communications, ranging and passive radar (detecting changes / motions, tracking objects in the environment) functionality. Changes and motions in the environment are detected by exploiting the specific preamble structure of the IEEE 802.15.4a packets. A sequence of packets transmitted through an environment is received. Each packet includes a preamble. The preamble in each packet is despread to update a reference multipath profile and to obtain a current multipath profile for a currently received packet. The reference multipath profile is compared with the current multipath profile to detect an object in the environment.

The invention discloses a CPU (Central Processing Unit) realizing method based on amplitude-comparison direction finding of a multi-frequency point omnibearing passive radar. A CPU and GPU (Graphic Processing Unit) heterogeneous hardware platform is adopted; a processing module with strong parallelism and the processing module with strong logicality are respectively realized on the GPU and the CPU; the platform is simple and high in use ratio; a system is simple in operation and strong in flexibility when being expanded; the coagulation and the angle measurement are carried out in the CPU; specifically, a coagulating-while-comparing amplitude angle measuring method is adopted; trace point coagulation is combined with amplitude-comparison angle measurement, so that the time for recombining the data after coagulation is omitted; the coagulation and angle measurement processes are embedded in multithreading, so that the time is further saved; and a target point containing the angle information is transferred to a terminal display control platform. According to the CPU realizing method provided by the invention, the problems that a target positioning effect of a single-frequency passive radar detecting system is inferior, the multi-frequency precision is high but the calculated quantity is large and the consumed time is long are solved. The CPU realizing method has the advantages of high processing speed, high angle measuring precision, and wide angle measuring scope, and can be applied to the target detection and positioning for the passive radar.

According to the invention, IEEE 802.15.4a packets are used for communications, ranging and passive radar (detecting changes / motions, tracking objects in the environment) functionality. Changes and motions in the environment are detected by exploiting the specific preamble structure of the IEEE 802.15.4a packets. A sequence of packets transmitted through an environment is received. Each packet includes a preamble. The preamble in each packet is despread to update a reference multipath profile and to obtain a current multipath profile for a currently received packet. The reference multipath profile is compared with the current multipath profile to detect an object in the environment.

The invention concerns a passive radar receiver for a received orthogonal frequency division multiplex-type signal consisting of symbol frames each emitted on coded orthogonal carriers. After formatting the received signals into digital symbols (S1 S1), a filtering circuit (2) eliminates by subtraction or using a covariance matrix, in the symbol signal at least unwanted signals with null Doppler effect so as to apply a filtered signal (X′) including essentially signals backscattered by mobile targets to a Doppler-distance correlator (4).

The invention relates to passive radars, electric wave transmission and wireless communication, provides a broadband recognition passive radar facing a complicated heterogeneous wireless communication irradiation source in the future, and is suitable for the development tendency of a new method for searching by a new theory in the field of the passive radars at the present.. According to the technical scheme, a broadband recognition passive radar system architecture design method comprises the following steps of: taking a complicated heterogeneous wireless communication emission signal as a passive radar irradiation source; constructing a passive radar irradiation source library based on a future broadband wireless communication technology through machine learning; then supplying a multi-system and multi-standard compatible broadband recognition passive radar system architecture; and finally, dynamically selecting an optimal waveform as the passive radar irradiation source according to an environment feedback and prior information supplied by the irradiation source library, and realizing heterogeneous fusion and preferential work of a complicated heterogeneous irradiation source. The method is mainly applied to design and manufacturing of the passive radars.

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.

The invention provides a single-frequency network-based passive radar system and a signal processing method for the same. A plurality of illumination sources for the system are used for simultaneously transmitting the same signals at the same frequency, and namely work in a single-frequency network system. A plurality of transmission stations and one or more receiving stations form a MISO (multiple-input single-output) or MIMO (multiple-input multiple-output) detection system, wherein the MIMO system is provided with a fusion center for performing communication and data transmission with each receiving station through a communication link and fusing processing results of each receiving station, and works at the same frequency; each transmission station is in the same form, and each receiving station is in the same form. A one-stop space-domain processing and single-frequency network defuzzification method is adopted for the signal processing method. According to the system and the method, a conventional broadcasting single-frequency network is used under the condition of no interference on broadcasting, so that the problems of severe clutter caused by the single-frequency network and fuzziness of the single-frequency network are solved, and the advantages of single-frequency network detection in frequency power reduction, hardware saving, detection stability and tracking continuity are fully exerted.

The invention relates to the field of passive radar, in particular to a software radio conception based broadband cognitive passive radar system architecture which has an environmental perception capability, a broadband sampling capability, a high-performance digital signal processing capability and a dynamic receiver parameter regulation capability. The method includes: step one, establishing a signal model which comprises non-orthogonal transmission signals, fading channels and direct wave and target echo receiving signals; step two, unifying a fuzzy function, Cramer-Rao bound and detection performances to a general detection theoretical framework; step three, assessing results based on a performance bound given by an assessment system; step four, improving signal quality of a direct wave channel and a target echo channel according to own characteristics of a mobile communication irradiation source. The method is mainly applied to design and manufacture of passive radar systems.

The invention relates to a passive radar detection method by use of synergistic or asynergistic satellite signals to detect low altitude targets, belonging to the technical field of space technology, which comprises a satellite and a ground passive radar system; wherein, the system comprises a plurality of detection stations and a data processing station, and interactive communications are conducted between the detection stations and the data processing station by means of radio or optical fiber transmission method. The signals, expanded frequency measurement codes and the signals reflected on low altitude aircrafts by and of the satellite, especially high radiation power satellite, are received by the detection station receivers of the passive radar with high sensitivity. After correlation, the path difference between the direct radiation signals of the satellite and the signals from the same source reflected by the low altitude targets can be derived; then, a group of passive detection equations can be established; the solutions can be obtained simultaneously. And a three-dimensional position coordinate of the low or super low altitude targets can be thus acquired. The invention has the advantages of huge detection area, small blind area, the capability of detecting low or super low aircrafts like cruise missiles and super low altitude airplanes passively at long range, and extensive application value for military use.

The invention discloses an aircraft target recognition method based on a single frequency network passive radar. Micro Doppler modulation characteristics generated by an aircraft target rotating part (such as a rotor, a propeller or a jet engine) are used for target recognition. Firstly, two-dimensional cross correlation processing is carried out on signals of a reference channel and a monitoring channel, and thus target detection is realized; then, micro Doppler characteristics corresponding to each transmitting station are extracted from different distance unit positions on a range-Doppler spectrum; and finally, information fusion technology is used for carrying out decision level fusion recognition on multi-angle characteristics. Micro Doppler characteristics provided by each transmitting station in the single frequency network at the same time are combined, attitude sensitivity of the target micro Doppler characteristics is reduced, and recognition accuracy is thus improved.

A method for improving geolocation accuracy in a passive radar warning receiver, using synchronized data curve-fit and interpolation to asynchronous and noisy receiver and navigation measurements over observation periods that are extended to reduce inaccuracies caused by noise. The present disclosure yields synchronized data samples at intervals short enough that constant-rate equations are valid, even though the actual motions over the observation interval may be more complex and have higher-order dynamics. It reduces noise, synchronizes data samples, and is readily adapted to motions with variable acceleration. The method generates rate samples short enough to satisfy constant rate assumptions, yet fit data over intervals long enough to enhances measurement accuracy by reducing measurement noise.

The invention relates to an object tracking technology of a passive radar, and discloses a multi-object tracking method of the passive radar. Positioning is carried out according to direction angle information of a multi-station passive radar, and a speed, acceleration and angle limited visualized method is used to initialize a track; and an IMM algorithm is used to track a moving object, a UKF algorithm is used to solve a nonlinear problem of a tracking system, a JPDA method is used to a multi-object association problem, and the track of the object is obtained, and the state of the object is estimated. Certain measurement interruption track is predicted, a new track within Tth+Tsm after interruption time is estimated reversely, a sequential association method is used to associate new and old tracks and obtain an examination matrix psiN*M, and the psiN*M is limited to solve an association confirmation matrix omegaN*M associated with the optimal track. Thus, multiple objects of the passive radar can positioned and tracked, the object estimating precision within the track initialization time is improved, and the interruption track association problem within the threshold time can be solved.

General method for extracting source distance information from any kind of received radiation, including electromagnetic and acoustic, without involving round-trip time or phase in any form, and thus more truly passive than existing passive radars. The method exploits the facts that radiation from a real source must comprise wavepackets of nonzero bandwidth, that the individual frequency components of a wavepacket must have consistent phase at the source, and that their instantaneous phases must increase linearly along the path in proportion to the respective frequencies, so that the phase gradient across the components must be proportional to the distance travelled. The invention simplifies over naïve phase gradient measurement by scanning the phase gradient at a controlled rate, thereby converting the gradient into normalized frequency shifts proportional to the scanning rate and the source distance. It mimics the cosmological redshift and acceleration, but at measurable levels over any desired range and even with sound. Potential applications include stealth and “unjammable” radars for the military, ranging capability for emergency services, commodity low-power vehicular and personal radars, simplification and improvements in radar and diagnostic imaging, improved ranging in general all the way from ground to inter-galactic space, “interference-free” communication systems including radio and television receivers, source-distance (or range-division) multiplexing improved cellphone power control and battery life, and continuous, transparent diagnostics for optical fibres, integrated circuits and transmission lines.

The invention discloses a method for fast realizing the signal processing of passive radar based on a GPU (Graphics Processing Unit). The method comprises the following steps of at a link of direct wave and clutter suppression, dividing whole data into N data blocks and dividing the data blocks into L data segments, wherein the number of data points within each data segment is M; splicing the data with the same data segment number, of each data block together in a way that the current segment of the No. N data block is spliced with the next segment of the first data block; enabling M*N threads by the GPU for parallel processing; at a link of coherent accumulation and walk correction, segmenting the data in a way that all the data are divided into n segments; grouping the continuous segments in a way that every DIM segments form one group; splicing the all groups of data together in sequence and storing such data in a continuous address space of a GPU video memory; and finally, carrying out GPU parallel processing on the each group of data. The method for fast realizing the signal processing of the passive radar based on the GPU is more applicable for the GPU parallel processing, and the higher speedup ratio can enable real-time processing demands to be met.

The systems and methods use Hermetic Transform processing to achieve higher resolution in space, time, and frequency measurements, leading to enhanced object detection, localization, and classification, and can improve several aspects of RADAR, including: phased-array beamforming, Doppler filter processing, pulse compression / replica correlation, and in the creation of higher resolution ambiguity function measurements for both multi-static active and passive RADAR.

The invention discloses a method for restraining flight path deception jamming through a remotely configured initiative and passive radar net. The method for restraining the flight path deception jamming through the remotely configured initiative and passive radar net mainly solves the problem that the prior art is large in calculated amount and large in data transmission amount. The method for restraining the flight path deception jamming through the remotely configured initiative and passive radar net comprises steps of 1, detecting a target through an initiative radar and a passive radar in the initiative and passive radar net and obtaining a measuring value of the target; 2, performing point trace correlated inspection on measuring values of the initiative radar and the passive radar, removing part of false targets of the initiative radar through a point trace correlated result Uij, tracking and filtering a reserved measuring value and obtaining target flight path information Bi'; 3, performing ambiguity processing on the point trace result Uij, tracking and filtering the measuring value of the passive radar through the processed result and obtaining the target flight path information; 4, performing flight path correlation detection on the target flight path information Bi' and the processed result and performing ambiguity processing on the target flight path information Bi' and the processed result; 5, identifying and removing false flight paths of the initiative radar through processed flight correlation result. The method for restraining the flight path deception jamming through the remotely configured initiative and passive radar net effectively restrains the flight path deception jamming and can be applied to the remotely configured initiative and passive radar net.

The present invention discloses a single channel LTE radar system based on communication / radar integration. The system comprises an up link, a down link and a radar signal processing unit of a radar receiver, wherein a reconstructed direct wave signal is generated via the up link comprising a channel coding module, a scrambling module, a digital modulation module, a layer mapping module, a pre-coding module and an OFDM symbol generation module orderly and is sent to the radar signal processing unit, and the down link comprises a timing synchronization module, a frequency offset estimation module frequency correction module combining a frequency offset estimation module, an OFDM demodulation module, a channel estimation module, an equalization module, a PBCH reception module, a PCFICH reception module, a PDCCH reception module and a PDSCH reception module. The single channel LTE radar system based on communication / radar integration of the present invention fully utilizes the mobile communication signal information, enables a passive radar system to be simplified and a reception terminal to be changed from a dual-antenna system into a single-antenna system, also enables the signal processing precision to be improved.

A non-scanning radar system is installed on an aircraft to detect and avoid bird strikes or collisions with other airborne hazards. Target amplitude, range, and Doppler tracking versus time are used to qualify the collision threat. Avoidance is based on a quick minor altitude change by the pilot or autopilot to exit the imminent bird or other airborne hazard altitude window. In one embodiment, a bistatic passive radar receiver antenna is used in conjunction with an existing geostationary satellite signal. Range and Doppler information are obtained via cross correlation processing of the hazard reflection signal with a direct path reference signal from the satellite.

The invention discloses a passive detection system for detecting a low-altitude target by using navigation radar signals and relates to the field of passive radars. The passive detection system comprises a non-cooperative navigation radar, a passive receiving system, a signal information processing module and a geographic information module used for displaying positioning results. The invention further discloses a method for passively positioning the low-altitude target by using the navigation radar. The method includes steps that: 1 the passive receiving system measures arrival angles of a direct arrival signal and a target echo; 2 direct arrival pulses are adopted to estimate the azimuth angle of a navigation radar emitting antenna scanning from a direct arrival path to a target reflection path; 3 the signal information processing module is adopted to obtain time delay of the target echo relative to the direct arrival signal; 4 measurement is obtained, a triangle formed by the navigation radar, the target and the passive receiving system is solved and three-dimensional coordinates of the target are obtained; and 5 the target position is given on an electronic map. The passive detection system and method have the capability of detecting the low-altitude target for maintaining electromagnetic silence and can achieve situation monitoring and early warning.

A bistatic passive radar system for tracking at least one target utilizing means for transmitting radar signals from at least one satellite platform in a geosynchronous orbit with the earth, means for receiving radar signals from a reflection from each target, means for tracking a position of each target over time, and means for computation of a fire control solution of each target.

The invention discloses a frequency selective surface in a combined guidance system of an active / passive radar, and belongs to the technical field of frequency selective surfaces. The frequency selective surface solves the technical problems in the prior art that a mixed-type FSS passive radar is small in working bandwidth, the active / passive radar is narrow in dual-band pass interval, and the radars cannot be used for the combined guidance system. The frequency selective surface provided by the invention comprises a plurality of metal paster units and a plurality of electric-control lumped elements, wherein the plurality of metal paster units are arranged periodically, any two adjacent metal paster units are connected through one electric-control lumped element, and the interior of each metal paster unit is provided with an opening. When the electric-control lumped elements are connected, the frequency selective surface has the high-pass filtering characteristic, can achieve the switching function of the passive radar which works at wide frequency band. When the electric-control lumped elements are disconnected, the frequency selective surface has the characteristic of wide-interval double-band pass. The frequency selective surface can be used for the cloaking of an antenna of an active / passive combined guidance weapon, and improves the viability and capacity of defense penetration of the active / passive combined guidance weapon.

The invention relates to a quick implementation method for passive radar range migration compensation and belongs to the technical field of radar target detection. The method comprises the following steps: (1) a direct wave signal and an echo signal received by a passive radar antenna are segmented and rearranged into two-dimensional matrices; (2) each row of the direct wave and the echo wave is transformed to the frequency domain; (3) the transformed direct wave matrix is multiplied by the conjugate transpose of the transformed echo wave matrix; (4) each row is extracted after being processed by a low-pass filter; (5) each column is subjected to CZT; and (6) each row is transformed to the time domain, and a cross-ambiguity function result subjected to migration compensation is obtained. Compared with a conventional range migration compensation method based on CZT and IFFT to achieve keystone transform, the provided method reduces operation steps and the amount of computation substantially while the gain accumulated is almost the same.

The invention provides a passive radar low-altitude object detection method. The distance between an object and an array is detected by installing a circular passive receiving radar antenna array, receiving OFDM communication signals reflected by a low-altitude slow-speed object and performing pulse compression, then a weak object under a low signal-to-noise ratio and strong interference is detected through a constant false alarm detection module, and finally, determination and advanced early warning of a low-altitude object with a potential threat are carried out through extracting the speed of the detected weak object. The method provided by the invention decreases the cost under the condition that the coverage scope is ensured by use of OFDM wireless communication signals through a passive radar system, and compared to a conventional OFDM phase-coded radar, is greatly simplified in terms of system; and the method is suitable for application in key areas which are covered by the OFDM wireless communication signals and require monitoring of low-altitude safety by use of such features of high utilization rate of an OFDM signal spectrum, good anti-multipath performance, high-distance resolution with broadband, adaptability of narrowband to a low noise-to-signal ratio and the like.

The invention relates to the field of signal sampling and signal detection, and in particular relates to a compressed sampling signal detection method based on a modulated wideband converter which detects the signals after obtaining the sampling value of a sub-Nyquist sampling rate through compressed sampling passive radar and electronic reconnaissance signals. The method comprises the steps of setting parameter, processing the signal entering an MWC structure with M parallel channels; computing the covariance matrix of a sampling matrix; getting the characteristic value of the covariance matrix and normalizing; computing the correlation coefficient of the normalization characteristic value; and judging whether the signal exists according to the obtain correlation coefficient and a threshold. With the application of the compressed sampling signal detection method based on the modulated wideband converter into the detection of broadband signals, the sub-Nyquist sampling can be ensured, and less data is used for storing under the premise of ensuring that the target can be detected out, and thereby the storage resources of a receiver are saved.

The present invention relates to the general field of radar tracking applied to multi-static radar systems. It consists of a method for coherently merging the individual tracks generated from the various bistatic bases that make up the system so as to generate and maintain global tracks so that an object detected by a single bistatic base is represented by the corresponding track and an object detected by a number of bistatic bases and giving rise to the creation of a number of individual tracks is represented only by a single global track.

A passive detector (10) includes a receiver (11) configured to collect passive radiation (12) in an environment, where detailed information about a portion of the passive radiation is estimated as a baseline of the passive energy. The passive energy is generated by a passive source unrelated to the detector. A monitor (24) is configured to measure a fluctuation in the baseline. A decision module (34) is coupled to the monitor to determine whether the fluctuation represents a presence or motion in the environment. Detection methods are also disclosed.

The invention belongs to the field of radar and communication signal identification and provides a transfer learning method for external radiation source signal identification. The transfer problem ofmodels obtained through training of different sampling rate signals can be solved. The method is not relevant to the sampling efficiency of a source domain and a target domain. Therefore, according to the adopted technical scheme, the passive radar external radiation source signal identification method based on transfer learning comprises the steps that one model is firstly trained on a samplingfrequency data set to serve as a basic network, then a model of the basic network and parameters are directly transferred to data set target domains having different sampling frequency, fine adjustment training is performed, and a neural network model including three layers of convolution and two whole connection layers is used for the basic network. The method is mainly applied to radar and communication signal identification occasions.

The present invention relates to the field of passive radars, and more particularly the field of the processing of the signals utilized by such radars. The signal processing method received according to one or more embodiments of the invention performs coherent processing, in order to purge spurious signals from the useful signal, including the reference signal and its multiple reflections, to regenerate the transmission signal and to perform a coherent integration of the signal received, by computing the cross-ambiguity between the signal received and the regenerated transmission signal. One or more embodiments of the invention also performs operations of non-coherent processing making it possible in particular to carry out extraction and Doppler distance purification operations making it possible to form blips and to eliminate the spurious blips present among the blips formed. The invention applies to passive radars operating on non-cooperating opportunity transmissions, such as FM transmissions intended for the public.

A system for bistatic radar target detection employs an unmanned aerial vehicle (UAV) having a ramjet providing supersonic cruise of the UAV. Deployable antenna arms support a passive radar receiver for bistatic reception of reflected radar pulses. The UAV operates with a UAV flight profile in airspace beyond a radar range limit. The deployable antenna arms have a first retracted position for supersonic cruise and are adapted for deployment to a second extended position acting as an airbrake and providing boresight alignment of the radar receiver. A mothership aircraft has a radar transmitter for transmitting radar pulses and operates with an aircraft flight profile outside the radar range limit. A communications data link operably interconnects the UAV and the tactical mothership aircraft, transmitting data produced by the bistatic reception of reflected radar pulses in the UAV radar antenna to the mothership aircraft.