457 results about "Passive detection" patented technology

A detection system for detecting a body near a doorway includes two detectors having one or more activation lines that overlap each other. With certain mounting arrangements, the detectors cover areas within and on both sides of the doorway. The detectors are meant to help prevent an already open door from accidentally closing on the body. The door is powered by a drive unit that ignores the detectors when the door is closed.

The present invention is a system and method that monitors upgrade availability for computer information on a user's computer and allows the user to determine which of the available upgrades will be downloaded to the user's computer and installed. The upgrade availability for computer information on the user's computer is monitored in the background, without user-intervention when the user connects to a network, such as the Internet. If any such upgrades are available, a flag is set to notify the user of such upgrades. The user is notified of any available upgrades when computer information is accessed for which an upgrade is available, and given a choice of whether or not to download the available upgrade(s). The downloaded upgrade(s) may then be installed by an installation means. In this manner, the present invention allows for the user to download only those upgrades desired by the user.

An apparatus and method for continuous, passive detection and measurement of tensile and compressional strain in a structure utilizing a shielded optic fiber, the optic fiber having one or more Bragg gratings thereon, the gratings and shield being disposed in a curved path on the structure and a baseline response for the grating is made using an optical source and detector. Changes in tensile or compressional forces on the structure will result in changes in the curve of the grating, resulting in a frequency shift for the returned light.

Techniques are provided for use with implantable medical devices or trial medical devices for wirelessly connecting the devices to external instruments such as tablet computers or smartphones. In an example where the medical device is an implantable neurostimulator, the neurostimulator passively detects wireless wake-up signals generated by the external instrument, i.e. the neurostimulator “sniffs” for advertisement signals generated by the external instrument. In response to passive detection of a wake-up signal, the implantable neurostimulator determines if a response is warranted and, if so, the neurostimulator activates its wireless transmission components to transmit an acknowledgement signal to the external instrument so as to complete a wake-up and handshake protocol. In this manner, power consumption within the implantable device (or within a similarly equipped trial medical device) can be reduced compared to devices that would otherwise periodically transmit advertisement signals even when no external mobile instrument is present.

The invention relates to a networking topologic structure of fleet formation and a design method for a combined multi-address system, belonging to the technical field of the aviation data link, radio navigation and aircraft automation. The invention provides a multi-address system and a networking topologic structure for networking communication and measurement of fleet formation, meets the passive detection and location and the cooperative attack task of the fleet formation to the moving-target. The invention provides the networking topologic structure which can realize the combined multi-address system and support the fleet formation on a DSP (Digital Signal Processor), an FPGA (Field Programmable Gate Array) apparatus and a radio frequency channel on an intermediate-frequency signal processing circuit board of a fleet link terminal. The invention provides two novel multi-address access systems of communication topologic configuration, namely the CDMA Code Division Multiple Access)/FDAM combined multi-address communication system of the fleet formation based on cross-link networking topology and a graded hierarchical multi-address communication system of the fleet formation based on tree topology. The former can support a single-hop access mode of total network coverage and the latter provides a multiple-hop access mode of total network coverage.

The invention relates to an island detection method of a photovoltaic grid-connected system. In views of the problems that independently-adopted passive detection mode is effective only when effective when mismatching degrees of source and load are large and a large non-detection zone (NDZ) can be accordingly provided; and when an active detection mode is independently-adopted, the system is disturbed, and therefore the disturbance results in instability of the system, and accordingly over-voltage / under-voltage is provided. An over-frequency / under-frequency detection method is combined with an improved impedance detection method to conduct island detection to the system, and therefore the NDZ is reduced to a minimum, quality of electric energy is improved and total harmonic distortion (THD) is reduced.

The invention, which belongs to the technical field of passive detection, discloses a three-station time-difference positioning performance test evaluation method. A three-station time-difference positioning performance test evaluation model is established, and deployment of a time-difference positioning system and a flight route of an airborne radiation source or airborne radar signal simulator are designed; on the basis of a positioning error test result of the whole flight route, an unknown parameter in an integrated time measurement error model is resolved; and with the integrated time measurement error model and a positioning error GDOP model, a positioning error at any position or a positioning error at any plane can be obtained. According to the invention, the resolving method of correlated parameters in the integrated time measurement error model as well as the positioning error in any station distribution mode and at any radiation source position are provided. Therefore, a three-station time-difference positioning performance test evaluation problem according to the background technology can be solved; defects of the ideal or fixed integrated time measurement error model can be overcome; and the method can be promoted to the ground test mode field without radiation source flight.

The invention provides a method for passive detection of moving objects based on physical layer information. The method is used for passively detecting moving objects with different speeds. Widely deployed commercial Wi-Fi equipment is used as a carrier. In addition to the traditional CSI amplitude information, CSI phase information is utilized in the invention. The change features of amplitude and phase information of a channel physical layer are extracted by a PCA algorithm, and relatively stable change features are further obtained by making use of the multi-antenna characteristic of an MIMO system to improve the accuracy and robustness of detection. Finally, the obtained features are used as input, and whether moving objects exist in an environment is predicted in a classified way by an SVM algorithm, so as to realize passive detection of moving objects.

A passive element is provided to facilitate passive detection of analytes, such as analytes, using an electromagnetic probe beam. The probe beam may be provided by a radar and/or lidar system. In one example, a passive element comprises a reference dipole and a detection dipole, the detection dipole having an associated analyte-sensitive element, such as a chemoresistive or bioresistive element. When the analyte-sensitive element is in a modified conducting state due to the presence of an analyte, the detection cross section is modified whereas a reference cross section is substantially unchanged by the presence of the analyte. A passive element may comprise a frequency selective surface, for example including a frequency-selective surface (FSS) embedded in a dielectric layer and using an analyte-sensitive impedance layer to modify the electromagnetic absorption properties, allowing analyte detection.

The invention discloses a direction of arrival estimation method based on co-prime array virtual domain equivalent signal atom norm expression. A problem of definition mismatch between a conventional atom norm definition and a co-prime array virtual domain equivalent signal model is solved. The direction of arrival estimation method comprises steps that a receiving end adopts a co-prime array to receive a signal, and modeling is carried out; an equivalent virtual signal corresponding to a co-prime array receiving signal is deduced; a theoretical model of a co-prime array virtual domain second-order equivalent multi-sampling fast beating signal is formed; the atom norm definition of the co-prime array virtual domain equivalent signal is acquired; an optimization problem based on the co-prime array virtual domain equivalent signal atom norm expression is set to re-establish a virtual domain covariance matrix; according to the re-established virtual domain covariance matrix, the direction of arrival estimation is carried out. The direction of arrival estimation method based on the co-prime array virtual domain equivalent signal atom norm expression is advantageous in that improvement of freedom degree performance is guaranteed, and at the same time, the non-meshing direction of arrival estimation is realized, and the method is used for passive detection and target positioning.

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 a location information field-based radiation source localization algorithm. The location information field-based radiation source localization algorithm comprises the following steps that: first step, correlation processing is performed on time segments of acquired data so as to extract time difference of arrival (TDOA) information; second step, grid points are arranged in an area; third step, a cost function is constructed, and the values of the cost function at each grid point in the rectangular area are solved; and fourth step, and a point where the value of the cost function is maximum in the area is selected as a target location. With the location information field-based radiation source localization algorithm of the invention adopted, limitations of the performance of an existing multi-station passive detection localization system can be eliminated, and fast and accurate localization of a target can be realized under non-vision-shared and multiple-target situations.

The invention discloses a product surface defect detection method. The method employs a passive detection mode, which means that the method does not give consideration to the defects of the surface of a product or the defects and the characteristics of the defects, removes a no-defect region in a process of image processing, and leaves a defect part image. The method comprises the steps: firstly carrying out the threshold segmentation through an OTSU algorithm, and carrying out the image binaryzation of a gray scale map of an original image; secondly setting a defect threshold window epsilon and carrying out the secondary segmentation of an obtained binary image so as to remove the defects and background noises; finally proposing a local inhibition solution in order to solve a problem of edge burr of the image of the product, thereby obtaining an accurate and clear real defect image. The proposed passive detection mode can reduce the operation burden of an algorithm and increase the processing speed of the algorithm, and also can remove a pseudo-defect part formed by the edge burr caused by the illumination unevenness, and achieve the quick and accurate detection of the surface defects of the product.

The invention discloses a rapid positioning method based on TDOA (Time Difference Of Arrival), mainly aiming to solve the problems when a tested target performs position solution depending on TDOA detected by a plurality of signal receivers under near and long distance scenes. The method mainly comprises the steps of: coordinate and distance equation establishment, centre distance solution, object coordinate solution, distance constraint and spherical surface relation constraint establishment, and solution of object coordinate corrected solution. The method can solve the problem of passive detection and positioning of an underwater vehicle, and can also be used for solving other positioning problems based on TDOA, such as radio positioning, ultrasonic wave positioning, indoor positioning, etc. Compared with a commonly used Chan algorithm, the rapid positioning method based on TDOA solves the problem of inconformity of near distance and long distance algorithms and existence of fuzzy solution, and furthermore improves precision and stability; compared with a Taylor algorithm, the rapid positioning method based on TDOA does not need external initial value and recursion operation, substantially reduces arithmetic labor, but does not change precision and stability.

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.

An assembly for passive detection of features at known locations of a conduit. The assembly is a sensor assembly particularly well suited for detection of casing collars at known locations of cased wells, such as segmented hydrocarbon wells. Thus, the assembly is able to provide real time positioning information relative to any tool coupled thereto which is being advanced in the well pursuant to a well application. Given that the detection takes place in a passive manner via the combination of a magneto-responsive sensor and voltage responsive device, no separate dedicated power source or additional electronics are required.

Some embodiments provide a self-configuring firewall for automatic detection and mitigation of security weaknesses. The self-configuring firewall performs passive and active vulnerability detection. Passive detection involves scanning software resources and configurations under firewall protection for vulnerabilities present in the software and software configurations. Active detection identifies vulnerabilities by subjecting the software resources and configurations to simulated malicious traffic. The identified vulnerabilities are mapped to attack signatures. The self-configuring firewall enables the attack signatures which in turn allow the firewall to detect traffic containing attacks directed to exploiting the vulnerabilities.

The invention relates to a computer generated image passive detection method based on fractal dimension in the technical field of digital images, which comprises the following steps: firstly, respectively performing sub-block screening to images in a natural image and computer-generated image library in a training stage; secondly, respectively computing fractal dimension of each image sub-block, and further obtaining a set of eigenvectors; thirdly, training the series of eigenvectors by a support vector machine to obtain parameters of an optimized classifier; performing the similar processingto images to be detected to obtain a fractal eigenvector, and performing classification authentication by using the optimized classifier obtained in the training state to obtain a detection result. The invention increases an expression window on the basis of the traditional difference box fractal dimension method and a data multiplexing and variable box height mechanism based on dynamic planning idea, which enable the method to have greater improvement on computation complexity and detection rate.

The invention provides a network fishing detection method and an apparatus thereof. The method comprises the following steps: acquiring a suspected fishing host name matching a fishing object keyword; acquiring a fishing Uniform Resource Locator (URL) path corresponding to a fishing object; jointing the suspected fishing host name and the fishing URL path to form a suspected fishing URL; detecting the suspected fishing URL, and determining whether the suspected fishing URL is a fishing URL or not. According to an embodiment of the invention, through a technique of actively acquiring the suspected fishing host name matching the fishing object keyword and the fishing URL path corresponding to the fishing object, jointing them to form the suspected fishing URL, detecting the suspected fishing URL, and determining whether the suspected fishing URL is a fishing URL or not, a problem that in the prior art passive detection triggered by a user can not deal with more and more rampant and general fishing attack is overcome, early discovery of a fishing website is realized, and fishing website detection efficiency is raised.

The invention discloses a combined estimation algorithm based on broadcast signal passive positioning, and the algorithm comprises the steps: carrying out the processing of a plurality of key techniques of a passive positioning system, and forming a practical passive positioning system; carrying out weak signal detection and extraction in a complex multi-path environment, carrying out combined estimation: the estimation of DOA (Direction of Arrival) of a target signal, the estimation of TD (time delay) of a wave arrival signal and the estimation of fd (frequency of doppler). The method starts the angle of array signal processing, and gives consideration to the complex environment of the target signal. The method achieves the invention of the time delay, Doppler frequency detection and DOA estimation of the weak target signal. A passive coherent positioning system based on the non-cooperative irradiation target passive detection technology is great in hiding performance, can detect a stealth target, has the capability of preventing low-altitude defense penetration, and therefor is of great strategic importance to the national modernization of national defense in a modern war environment.