30 results about "Skywave" patented technology

The invention discloses an ionospheric-reflection-based time difference of arrival positioning method for a shortwave radiation source, and belongs to the technical field of shortwave communication. The method comprises the following steps of selecting corresponding receiving sites to acquire found and monitored target signals; locally compressing the target signals, and transmitting the target signals to a master server; estimating propagation channels of the signals received by each receiving site, performing joint positioning error estimation in combination with each time difference of arrival, optimizing a positioning result according to the geographic position distribution of each receiving site and the variation amplitude of ionospheric parameters and the time differences of arrival, and giving a positioning error. According to the method, a conventional shortwave receiving antenna can be utilized, a large direction-finding antenna array is not required, the reflection influence of an ionospheric layer on shortwave sky wave signals is taken into full account, and the time differences of arrival of the signals at different receiving sites through different paths are used for positioning the shortwave radiation source; the method is disclosed according to actual needs, is particularly applied to regions where large antenna arrays cannot be erected, and is practically significant, and manpower and funds can be greatly saved.

The invention discloses a sky-wave beyond visual range radar adaptive space-time joint interference-resistant method which inhibits interference by comprehensively utilizing two methods of adaptive beamforming and interpolation and compensation after a time domain is eliminated and achieves the purpose of making up for each other deficiencies through reasonable scheduling strategies. The transient interference entering a side lobe is resisted by utilizing the adaptive beamforming of a space domain, and the transient interference entering a main lobe is inhibited through the interpolation and the compensation after the time domain is eliminated, therefore compensating errors caused by time domain elimination and beam distortion caused by main lobe interference are prevented; and a diagonal loading amount which is in proportion to interference strength is formed for the non-transient interference entering the main lobe through interference space distribution information, therefore the strong main lobe interference is prevented from causing the serious distortion of the shapes of adaptive beams. The invention is established on the basis of a dimension-reducing beam space adaptive beamforming method, thereby greatly reducing the amount of signal processing calculations; and concrete steps are seen in an attached figure. The invention is not limited to a sky-wave beyond visual range radar system, can be widely applied to large-sized phased array radars of multiple types and has popularization and application value.

The invention discloses a frequency-domain super-resolution micro-multipath height finding method of a sky-wave beyond visual range radar, wherein the frequency-domain super-resolution micro-multipath height finding method is suitable for a signal processing system of the sky-wave beyond visual range radar. The frequency-domain super-resolution micro-multipath height finding method comprises the following specific steps of: filtering an interested target and multipath signals thereof by using band-pass FIR (Finite Impulse Response) filtering; estimating a mean distance value of the interested target by using a super-resolution method, and designing a distance rectangular projection matrix to filter and remove partial redundant micro-multipath signals; forming a Doppler domain weighted signal sub-space, estimating a mean Doppler value of the Doppler domain weighted signal sub-space; and calculating a Doppler parameter by using a micro-multipath model, correcting by using the mean Doppler value to form a Doppler projection matrix, matching the weighted signal sub-space with the Doppler projection matrix, searching to obtain the estimated height value of the target, wherein the specific steps are shown in figure 1. The method has the advantage of reducing the probability of matching failure caused by noise and parameter errors of an ionization layer. The technology disclosed by the invention is not limited to a sky-wave beyond visual range radar system and can be widely applied to a target height finding occasion with a ground multipath effect, and has popularization and application values.

The invention discloses a buoy-type high-frequency ground wave radar system. A buoy platform is used as an offshore carrier of a ground wave radar. A sky wave emission subsystem is arranged on a shore base and emits a high-frequency electromagnet wave. After the high-frequency electromagnet wave is refracted by an ionized layer and is reflected by a sea surface, a sky wave signal is formed. An attitude measurement subsystem measures and acquires attitude data of the buoy platform in real time. A ground wave radar subsystem adopts the ground wave radar to receive a ground wave signal, processes the signal to form a ground wave doppler spectrum. Simultaneously, the sky wave signal is received, ionized layer disturbance compensation is performed on the sky wave signal in a frequency domain and then the sky wave signal is processed to form a sky wave doppler spectrum. The ground wave radar subsystem reconstructs an actual geographic coordinate system according to the attitude data measured by the attitude measurement subsystem and then the ground wave or the sky wave doppler spectrum is used to inverse wind wave flow data in the reconstructed actual geographic coordinate system. The sky wave emission subsystem and the ground wave radar subsystem carry out time synchronization through a GPS synchronization networking mode. The system can detect a sea area with any distance and is suitable for high sea detection.

The invention discloses a method for simultaneously receiving sky wave and ground wave BVR radar signals. A distance offset method is used for transmitted signals on a sky wave transmitting station and a ground wave transmitting station so that a ground wave radar station on a shore base can simultaneously receive echo signals obtained by signals transmitted by a sky wave radar and a ground wave radar and scattered by a sea surface or a ship or a low altitude flight object. The method is simple and convenient to achieve, distance offset only needs to be conducted on sky wave transmitting signals and ground wave transmitting signals, it is guaranteed that the ocean of the sky wave radar and the ground wave radar or an object echo wave spectrum is within the bandwidth of a receiver filter, and aliasing of the distances and spectrum can not happen. An existing ground wave radar receiving system is used so that the purpose that the two BVR methods of sky wave transmitting and ground wave transmitting can be simultaneously used for detecting the ocean or target can be achieved. The combined detection mode can improve the detection accuracy of ocean surface dynamic parameters such as wind, waves and currents, the detection distance of a high-frequency BVR radar system is increased, and close distance fine detection and long distance ocean surface dynamic element detection are achieved.

The invention provides a method for removing non-linear phase pollution from a sky wave OTHR (over-the-horizon) radar echo signal, which relates to the field of the method for removing the non-linear phase pollution from the sky wave OTHR (over-the-horizon radar) echo signal and aims at solving the problems that the existing non-linear phase pollution has an effect on the sky wave OTHR echo signal and further reduces detecting performance under all kinds of conditions, especially under the lower signal-to-noise ratio. The method provided by the invention comprises the following steps that a data acquisition module collects to-be-processed sky wave OTHR time domain data; a data selecting module converts the to-be-processed sky wave OTHR time domain data; a pollution function computing module obtains a non-linear phase pollution function; and a signal correcting module obtains the sky wave OTHR echo signal after being subjected to removing the non-linear phase pollution. The method provided by the invention solves the problem of influence caused by the non-linear phase pollution in the sky wave OTHR radar echo signal, obviously reduces errors and has better effect under the lower signal-to-noise ratio. The method provided by the invention is used for processing the sky wave OTHR radar echo signal.

The invention relates to a short-wave remote radiation source one-step locating method based on wide-area distributed single-antenna receiving. The method comprises the steps: building a mathematic model of an arrival signal relative to a short-wave remote radiation source position function based on the short-wave antenna signal propagation principle; converting the wide-area distributed single-antenna received data into frequency domain data based on the technology of Fourier transform, and building a mathematic function model of the short-wave remote radiation source position and the heightof an ionized layer through an initial measured value of the height of the ionized layer and the maximum likelihood estimation criteria; finally obtaining the short-wave remote radiation source position information in a one-step mode based on the particle filtering or iteration optimization algorithms. According to the invention, there is no need of a large-scale array receiving station, and the method can achieve the high-precision one-step locating of the short-wave radiation source on the basis of a conventional wide-area distributes short-wave network through the single-channel receiving and algorithm software updating. The performances of the algorithms are reliable, and the method has great values in the fields of civil short-wave radio management and military short-wave radio detection.

The invention discloses a high-frequency sky-ground wave MIMO radar realization method, and provides an effective solution for the problems of multipath and multi-mode effect and clutter Doppler expansion and the like for a sky-ground wave over-the-horizon radar. A radar system is formed by a plurality of sky wave transmitting stations and a plurality of ground wave receiving stations. Each transmitting station and each receiving station are formed by a plurality of antenna units, so that coexistence of distributed and intensive MIMO radars is realized, and spatial resolution is improved, and multi-angle observation can be realized. By allocating different frequency bands or phases to transmitting subunits, a multiplexed orthogonal effect of transmitting signals is realized. The receiving stations realize pulse compression through frequency mixing and filtering, so that separation of multipath orthogonal signals is realized. The multi-angle observation enlarges detection range and improves detection precision; and MIMO virtual array elements enable the sky-ground wave MIMO radar system to have flexible wave beam formation capability, and influence from different-spatial-orientation multipath and multi-mode effect and clutter expansion due to ionosphere contamination in the sky-ground wave radar can be eliminated properly.

The invention discloses an improved ML (maximum likelihood) skywave radar maneuvering target parameter estimation method and belongs to the radar communication technical field. According to the method, the maneuvering target signals of a skywave radar are modeled into a generalized phase polynomial; and a received signal likelihood function is maximized, so that the parameter estimation of a maneuvering target can be realized. In order to avoid matrix inversion computation in a traditional likelihood function, the maximization problem of the likelihood function is converted into the optimization problem of overdetermination nonlinear least square estimation, so that high-precision maneuvering target parameter estimation under a low signal to noise ratio can be realized. Compared with a traditional maneuvering target parameter estimation algorithm, the method of the invention can not only achieve higher-accuracy parameter estimation under a lower signal to noise ratio, but also can estimate the motion parameters of a plurality of maneuvering targets simultaneously.

The invention relates to a non-cooperative short-wave radiation source wide-area distributed short-wave network single-antenna time difference positioning method. The method provided by the inventioncomprises the steps that a sky-wave propagation signal of a short-wave radiation source is collected, and a suitable receiving station is selected; the collected data are locally compressed and transmitted to a wide-area distributed short-wave network main station server; a main station is used as for reference to estimate the time difference of each receiving station relative to a main receivingstation; and finally, a positioning result is optimized according to the geographical distribution of each receiving station and the ionospheric height parameter and time difference. According to theinvention, the method is based on a single short-wave receiving antenna and a single-channel receiver of each station in the existing wide-area distributed short-wave network; short-wave radiation source positioning is realized by using the time difference generated by the short-wave sky-wave propagation signal which reaches each receiving station through different paths; rebuilding a large receiving station is not needed, which saves a lot of manpower and funds; and the method has important promotion and application values in both civil short-wave radio management and short-wave military technical investigation.

An electromagnetic vector sensor (EMVS) system, having a plurality of EMVS devices consisting of a plurality of loop antenna elements spatially orthogonally integrated with and electrically isolated from a plurality of dipole antenna elements, mounted on a rotatably adjustable platform having a true north orientation, including active circuitry residing in antenna housings, and external executing software programs causing the active circuitry in cooperation with the EMVS device and receivers to determine angle of arrival and resolution of incoming wave vectors and polarization of incoming signals and to perform accurate high frequency geolocation signal processing; the programs which perform calibration and antenna element placement determination operations, also cause the system to collect data of known transmitted high frequency skywave signals, and estimate direction of arrival of unknown signals by detecting, resolving and measuring components of an electric field and a magnetic field at a single point.

The embodiment of the invention relates to an ionospheric D layer detection system and method based on multi-station lightning low-frequency pulse signals. The system comprises at least two lightning low-frequency pulse signal detection acquisition devices in communication connection and a central processing device; each lightning low-frequency pulse signal detection acquisition device is used for detecting and acquiring and processing the lightning low-frequency pulse signals to obtain a sky-wave ground-wave pulse pair and the time and arrival time difference thereof; the center processing device is used to invert the height of the ionospheric layer D according to the relationship between the arrival time difference and the path difference of the sky wave and the ground wave. The system and method utilize lightning discharge as a radiation source, prevents high-power VLF-LF electromagnetic waves generated artificially, and greatly saves energy. In addition, because the lightning discharge can occur in different locations around the world, reasonable adjustment of lightning low-frequency pulse signal detection acquisition devices can measure the height of the ionosphere at different locations. The system and the method can be popularized and applied in a wide range, improve adaptive range and utilization rate of the ionospheric D layer detection system.

The invention discloses a sky wave positioning method applied to a LORAN system. The method is particularly implemented according to the following steps of: step 1, determining a propagation distancedbl of a sky wave according to a local arrival time tau rec and a transmission time tau tran; step 2, judging whether a sky wave propagation model is an illumination area model or a shadow area modelaccording to the size of the dbl; step 3, solving pseudo-range observation quantity rho of a sky wave receiving point and a transmission point; and step 4, simultaneously receiving the sky waves transmitted by the n sky wave transmitting stations by using a local LORAN receiving device to form an equation, and obtaining a sky wave receiving position x equal to [x, y, z] <T> and a local clock difference delta t. The sky wave positioning method applied to the LORAN system solves the following problems: the positioning methods existing in the prior art are based on ground wave signals, a stationchain is needed for the positioning, and the action range is small.

An electromagnetic vector sensor (EMVS) system, having a plurality of EMVS devices consisting of a plurality of loop antenna elements spatiatally orthogonally integrated with and electrically isolated from a plurality of dipole antenna elements, mounted on a rotatably adjustable platform having a true north orientation, including active circuitry residing in antenna housings, and external executing software programs causing the active circuitry in cooperation with the EMVS device and receivers to determine angle of arrival and resolution of incoming wave vectors and polarization of incoming signals and to perform accurate high frequency geolocation signal processing; the programs which perform calibration and antenna element placement determination operations, also cause the system to collect data of known transmitted high frequency skywave signals, and estimate direction of arrival of unknown signals by detecting, resolving and measuring components of an electric field and a magnetic field at a single point.

A sky-wave radar system model of an anti-terminal high-altitude area defense system, including the command vehicle, the No. 1 transmitting antenna array vehicle, the No. 2 transmitting antenna array vehicle, the No. 3 transmitting antenna array vehicle, the No. Antenna array vehicle, No. 6 transmitting antenna array vehicle, No. 7 transmitting antenna array vehicle, No. 8 transmitting antenna array vehicle, No. 9 transmitting antenna array vehicle, No. 1 receiving antenna array vehicle, No. 2 receiving antenna array vehicle, and No. 3 receiving antenna Array vehicle, receiving antenna array vehicle No. 4, receiving antenna array vehicle No. 5, receiving antenna array vehicle No. 6, receiving antenna array vehicle No. 7, receiving antenna array vehicle No. 8, receiving antenna array vehicle No. 9, and receiving antenna array vehicle No. 10 The vehicle, the No. 11 receiving antenna array vehicle, and the No. 12 receiving antenna array vehicle are different from traditional radar systems and have the functions of anti-low-altitude penetration, anti-stealth, anti-radiation missile, and anti-electronic interference. They are strategic early warning equipment for our country. Leap-forward development provides the foundation and is of great significance for improving the construction of the strategic early warning network.

The present invention relates to a leakage management system and a leakage location prediction method. The leakage management system, according to the present invention, comprises: detection units (100-N) which are installed on a pipe and acquire and detect a skywave RF and a vibration sound wave; a management server (200) which learns data on the variation of the vibration sound wave according to the change in time, and outputs pipe state information and vibration sound wave location information; and a terminal (300) which visually provides a detection mark in accordance with the pipe state information and the vibration sound wave location information. The leakage location prediction method, according to the present invention, comprises the steps of: acquiring a leakage model by learning collected leakage data (S100); receiving a skywave RF and a vibration sound wave from detection units (S200); by using the leakage model, outputting pipe state information from the received vibration sound wave (S300); and outputting vibration sound wave location information from the received skywave RF and vibration sound wave (S400).