137 results about "Radar reflectivity" patented technology

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 of radar-imaging a scene in the far-field of a one-dimensional radar array, comprises providing an array of backscatter data D(f_m, x′n) of the scene, these backscatter data being associated to a plurality of positions x′_n, n=0 . . . N−1, N>1, that are regularly spaced along an axis of the radar array. The backscatter data for each radar array position x′n are sampled in frequency domain, at different frequencies f_m, m=0 . . . M−1, M>1, defined by f_m=f_c−B/2+m−Δf, where f_c represents the center frequency, B the bandwidth and Δf the frequency step of the sampling. A radar reflectivity image 1(α_m′, β_n′) is computed in a pseudo-polar coordinate system based upon the formula (2) with formula (3) where j represents the imaginary unit, formula (A) is the baseband frequency, FFT2D denotes the 2D Fast Fourier Transform operator, α_m′, m′=0 . . . M−1, and β_n′, n′=0 . . . N−1 represent a regular grid in the pseudo-polar coordinate system, and P_max is chosen >0 depending on a predefined accuracy to be achieved. A corresponding method of radar-imaging a scene in the far-field of a two-dimensional radar array is also proposed.

A radar absorbing composite includes a (CNT)-infused fiber material disposed in at least a portion of a matrix material. The composite absorbs radar in a frequency range from about 0.10 Megahertz to about 60 Gigahertz. The CNT-infused fiber material forms a first layer that reduces radar reflectance and a second layer that dissipates the energy of the radar. A method of manufacturing this composite includes disposing a CNT-infused fiber material in a portion of a matrix material with a controlled orientation of the CNT-infused fiber material within the matrix material, and curing the matrix material. The composite can be formed into a panel which is adaptable as a structural component of a transport vessel or missile for use in stealth applications.

A weather radar system for improving output of potential lightning and hail weather conditions. An exemplary system includes a processor that receives and stores the weather radar reflectivity values into a three-dimensional buffer, receives an outside air temperature value, and determines freezing level based on the received outside air temperature value. The processor generates lightning icon(s) when a reflectivity value stored at cell(s) of the three-dimensional buffer above determined freezing level is greater than a first threshold amount. Also, the processor adds 1.6 km to the determined freezing level and generates hail icon(s) when a reflectivity value stored at cell(s) at the determined freezing level plus 1.6 km are greater than a second threshold amount. The display device displays the hail and lightning icons when an altitude value that corresponds to the cells associated with the generated lightning icons has been selected for display.

An embodiment of the invention provides an X-band dual-polarization weather radar quantitative precipitation measurement method and an X-band dual-polarization weather radar quantitative precipitationmeasurement system. The X-band dual-polarization weather radar quantitative precipitation measurement method comprises the steps of: utilizing an X-band dual-polarization radar to obtain radar data in a detection range, and using a laser raindrop spectrograph to obtain an actually measured raindrop spectrum of a detection point; acquiring a radar reflectivity factor and an attenuation rate; acquiring an actually measured rainfall rate and a radar reflectivity factor true value of the detection point based on the actually measured raindrop spectrum, acquiring an attenuation rate true value ofthe detection point through T matrix scattering simulation, acquiring a rainfall function in the detection range through fitting the actually measured rainfall rate and the attenuation rate true value, and further acquiring a rainfall rate; inverting the rainfall rate by using the attenuation rate if the radar reflectivity factor is greater than a first set threshold value; and acquiring an attenuation rate function in the detection range through fitting the radar reflectivity factor true value and the attenuation rate true value is the radar reflectivity factor is not greater than the first set threshold value, and then acquiring a rainfall rate in the detection range based on the attenuation rate function. The X-band dual-polarization weather radar quantitative precipitation measurementmethod and the X-band dual-polarization weather radar quantitative precipitation measurement system can acquire more precise predicted rainfall rates.

A system and method to build a radar reflectivity forecast mosaic from a collection of radar sites. The radar data from multiple radar sites is processed to create movement information for all of the precipitation areas. The movement information and precipitation areas are then mosaicked in a common geographical framework to create forecasted radar reflectivity mosaics. By using the reflectivity information and movement information from multiple radars, a wider scale, more coherent radar forecast can be generated.

The present invention is directed to system and method of processing meteorological data. The process comprises receiving a meteorological data corresponding to a geographic region from at least one meteorological data source for a selected time slice, with the meteorological data including radar reflectivity data. The system processes the meteorological data to derive probability of severe hail for points within the geographic region, processes the meteorological data to derive vertically integrated liquid for the points within the geographic region, and processes the meteorological data to derive enhanced echo tops for the points within the geographic region. The system processes the vertically integrated liquid and the enhanced echo tops to derive vertically integrated liquid density for the points within the geographic region and processes the probability of severe hail and the vertically integrated liquid density to derive derived hail index numbers for the points within the geographic region. The system generate data packets of the derived hail index numbers, with each of the derived hail index numbers corresponding to a local geographic point.

The present invention discloses a spaceborne radar and ground-based radar reflectivity factor data three dimensional fusion method. According to the present invention, by using the precipitation radar (PR) data of high vertical resolution as the output of a neural network and the ground radar (GR) data of high horizontal resolution and low vertical resolution as the input, a non-linear relationship of a PR and a GR is established, thereby fusing into the three dimensional reflectivity factor data having the high vertical and horizontal resolution. Based on a neural network algorithm, the PR and GR reflectivity factor data three dimensional fusion is carried out to obtain a fine three dimensional structure of an intensity echo which is very important for the later applications, such as the fine detection and tracking of a middle and small-scale convective weather process, the subsequent quantitative rainfall measurement, the radar data assimilation in the middle-scale forecast, etc.

The invention relates to an intensity calibrating method of all-digital array phased-array weather radar. The intensity calibrating method includes the steps that a radar monitoring terminal controls a correction extension set to send out simulation target signals, and a product terminal calculates an actual pulse pressure gain Gp; the radar monitoring terminal controls the correction extension set to send out a plurality of linear frequency modulation simulation target signals with fixed and sequentially and gradually attenuated echo power values, after the linear frequency modulation simulation target signals are processed by a signal processor, echo signal intensity values and spectrum processing signal intensity values are produced and sent to the product terminal through a network so as to be recorded into an intensity calibrating and testing record list, and an intensity curve yDVIP and a spectrum processing intensity curve yFFT are produced after fitting is conducted on the intensity calibrating and testing record list through the least square method; the product terminal inversely calculates echo power Pr when the radar normally works; the value of the obtained echo power Pr is substituted into an improved radar meteorological equation to obtain the value of a radar reflectivity factor dBZ. By means of the method, the special implementation steps and special testing processes of all-digital array weather radar intensity calibrating are established, and the method is fit for engineering practice and is simple, practical and high in calibrating accuracy.

The invention provides a metallic ball calibration method for an X-band solid dual-polarization weather radar, and the method comprises the steps: respectively selecting a test point in a broad pulse detection range and a narrow pulse detection range of the radar; placing a metallic ball at each test point; calculating a corresponding radar observation elevation angle, an radar observation azimuth angle and a radar observation database number for each metallic ball through employing the GPS information of each metallic ball and the longitude and latitude and height information of the radar; setting a calibration observation mode, and obtaining the observation data, wherein the calibration observation mode comprises the horizontal change range of a radar observation azimuth, the change range of the radar observation elevation angle and a stepping angle, and the observation data comprises a radar reflectivity factor observed value and a difference reflectivity factor observed value; and enabling the radar reflectivity factor observed value and the difference reflectivity factor observed value to be respectively compared with a reflectivity factor theoretical value and a difference reflectivity factor theoretical value, wherein the differences serve as the measurement error of the radar; and correcting the detection result of the radar in a corresponding detection range through the measurement error.

A system and method for presenting wind speed information in a manner so as to be easily understood and appreciated by viewers of televised weather report presentations and the like. Wind speed information is presented as a planar representation of three-dimensional wind speed data using contour lines, delineating areas with a planar location in the three dimensional data, overlaid on a geographic map display either alone, or in combination with radar reflectivity information. Wind velocity information received from a weather radar system, such as NEXRAD, relative to the weather radar is converted to absolute wind speed information for display.

The invention discloses an inversion method for microphysical parameters of liquid cloud. The inversion method mainly includes the following process: according to radar reflectivity factors provided by a millimeter waves cloud radar, based on the optimal estimation theory, adopting an empirical formula calculation value as a prior value, assuming that particle spectrum submits to logarithmic normal distribution, a function relationship of radar reflectivity factors and liquid cloud physical parameters is established, and the inversion optimal solution is obtained in a condition when the difference value weighing of to-be-inverted parameters, the prior value, the radar reflectivity factors and function calculation value achieves the minimum value. Besides, according to an error transmission theory, uncertainty of liquid cloud microphysical parameters is calculated. The invention can make up a shortcoming of poor adaptability of a traditional empirical formula. Also, besides, common cloud particle diameter and cloud water content, particle concentration and distribution width can also be obtained; the inversion result is more comprehensive. Since the radar reflectivity factor in real time monitoring is adopted for prior value calculation, the inversion result accuracy is improved.

The invention discloses a ground-based terahertz cloud detection radar system and a detection method thereof. A linear frequency modulation signal generation module generates linear frequency modulation signals with an adjustable pulse width; a frequency synthesizer module generates transmitting excitation signals and receiving excitation signals; a terahertz transmitting module generates terahertz transmitting signals; a terahertz receiving module converts terahertz echo signals to intermediate frequency signals; an intermediate frequency signal receiving and processing module generates baseband signals; a signal processing module carries out signal processing on the baseband signals; and an upper computer completes cloud observation data inversion processing on a signal processing result of the signal processing module. A linear frequency modulation working system and an adjustable pulse width are adopted, a high distance resolution can be acquired, requirements on the system transmitting power can be reduced, cloud observation from a ground near distance to a far distance can be met, radar reflectivity factor information with high cloud profile resolution can be provided, cloud space-time and cloud weather macro and micro information of an observation area can be acquired further, and the system and the method can also be used for detection of tiny particles such as haze in the environment.

The invention relates to a correction method and system for radar reflectivity factors of a dual polarization radar. The method comprises: when raindrop spectrum data of at least one of the pluralityof raindrop spectrometers disposed around the dual polarization radar is acquired, determining that there is precipitation at at least one raindrop spectrometer, and performing a scattering simulationinversion based on the raindrop spectrum data to obtain radar polarization parameters; fitting a relationship between AH-KDP and AH-ZH according to the radar polarization parameters to obtain parameters of a region where the dual polarization radar is located; and obtaining corrected radar reflectivity factors according to the parameters, observation values of the radar polarization parameters, and a preset algorithm. Therefore, the invention can realize attenuation correction and partial occlusion correction of the radar reflectivity factors based on different precipitation processes in different regions.

The invention discloses an NRIET quantitive precipation estimation method based on cloud classification and machine learning. The quantitive precipation estimation method based on cloud classificationand machine learning comprises the steps of first preprocessing radar data and rain gauge data, and matching a radar reflectivity with rain gauge precipation data based on a site; identifying different cloud systems such as strati and convective clouds according to the radar reflectivity intensity; then performing fitting training in real time using a machine learning regression algorithm to obtain a relationship model between cumulative precipation and radar combined reflectivity; and finally, applying the relationship model between cumulative precipation and radar combined reflectivity to radar combined reflectivity lattice field data in real time to obtain a quasi-real-time quantitive precipation estimation field.

The invention provides a short temporary rainfall forecasting method and device, and relates to the technical field of meteorologic weather forecast. The short temporary rainfall forecasting method comprises the following steps: obtaining combined reflectivity factor data at T moment and non-divergent level flow field data within T+t; interpolating the non-divergent level streamline flow data intoa combined reflectivity factor coordinate system to obtain interpolation flow field data; and obtaining weather radar reflectivity factor data within T+t according to the extrapolation of the interpolation flow field data and the combined reflectivity factor data. According to the short temporary rainfall forecasting method and device provided by the embodiment of the invention, the rainfall forecasting hit rate can be improved, and the false alarm rate is reduced.

The invention relates to a precipitation classification method and system. The method comprises the steps that precipitation observation data is collected; based on radar reflectivity factors and Doppler velocities, the precipitation observation data is classified, and precipitation types are obtained; a Z-I relational model corresponding to the precipitation types is constructed, wherein Z refersto the radar reflectivity factors, and I refers to rainfall intensity; and the Z-I relational model is utilized to perform precipitation classification on to-be-classified data. Through the scheme, the precipitation types can be classified quickly through radar data, therefore, an accurate Z-I expression can be obtained, and the accuracy and efficiency of radar quantitative precipitation estimation are improved.

A system and method for adaptation of a radar receiver in response to frequency drift in a transmission source is disclosed that utilizes a stable local oscillator established at a single, non-fluctuating frequency and compensates for transmission frequency fluctuation in the signal processor module. The disclosed system and method use mathematical processing techniques to compensate for variations in transmitter frequency during baseband processing of radar reflectivity signals. The system estimates the frequency of the transmitter to a high degree of accuracy and mathematically converts the reflectivity signal energy to a baseband intermediate frequency which is adjusted to compensate for fluctuations in transmitter frequency. A digital down converter circuit and numerically controlled oscillator circuit are also utilized to convert reflectivity signal energy to baseband and compensate for transmitter frequency drift. These new systems allow the stable local oscillator frequency to remain constant and thereby increase receiver stability.

A system and method for probing a specimen to determine one or more components by utilizing a first signal to excite the specimen at a nuclear quadrupole resonant frequency and observing changes in a specimen property. One exemplary property may be dielectric constant. Another exemplary property may be magnetic permeability. In one embodiment, the first signal is unmodulated and a second signal is observed for the presence of modulation at the frequency of the first signal. Alternatively, the first signal may be modulated and the second signal may be observed for the presence of the modulation. A system is disclosed wherein the specimen is excited using the first frequency and a radar at the second frequency is used to observe changes in radar reflectivity of the specimen due to the excitation.

The invention discloses a method for reconstructing vertical profiles of airborne multi-scan meteorological radar targets. The vertical profiles of the meteorological targets at the fronts of aircrafts can be displayed by the aid of meteorological echo information acquired by airborne multi-scan meteorological radar, and altitude-dimension intensity change and distribution ranges of reflectivity factors of meteorological target radar can be quickly, accurately and comprehensively reflected. Besides, at least eight layers of meteorological target information are acquired by the aid of the airborne meteorological radar in multi-scan work modes, and metrological target reflectivity factor change rule statistical models are innovatively built by means of statistics by the aid of metrology in information reconstruction procedures; the vertical profiles of the meteorological targets right ahead routes of the carrier aircrafts can be truly and completely represented by the aid of the multi-scan echo information. The method has the advantages of simplicity and convenience in operation. In addition, the quantities of processed data are low as compared with the traditional method, and the method has low requirements on systems and is high in reconstruction precision.