RCS Data Research Articles

Research on RCS Data Validation Based on SPWVD

Research on RCS Data Validation Based on SPWVD

A Compatible Estimation Method for Biomass Factors Based on Allometric Relationship: A Case Study on Pinus densata Natural Forest in Yunnan Province of Southwest China

Using various biomass factors, such as biomass expansion factor (BEF) and biomass conversion and expansion factor (BCEF), yields different results for estimating forest biomass. Therefore, ensuring compatibility between total biomass and its components when employing different biomass factors is crucial for developing a set of rapid and efficient models for large-scale biomass calculation. In this study, allometric equations were utilized to construct independent models and the proportional values (root-to-shoot ratio (Rra), crown-to-stem ratio (Rcs), bark-to-wood ratio (Rbw), foliage-to-bark ratio (Rfb), and wood biomass-to-wood volume (ρ)) by using the mean height (Hm) and the mean diameter at breast height (Dg) of 98 Pinus densata plots in Shangri-La, Yunnan province, China. The compatible methods were applied to reveal the compatibility between the total biomass and each component’s biomass. The results showed the following: (1) Both the independent model and compatible model had a higher accuracy. The values were greater than 0.7 overall, but the foliage biomass accuracy was only 0.2. The total biomass and the component biomass showed compatibility. (2) The accuracy of BEF and BCEF exceeded 0.87 and the total error was less than 0.1 for most components. (3) The mean BEF (1.6) was greater than that of the Intergovernmental Panel on Climate Change (IPCC) (M = 1.3), and the mean BCEF was smaller than that of the IPCC; the values were 0.6 and 0.7, respectively. The range of BEF (1.4–2.1) and BCEF (0.44–0.89) were all within the range of the IPCC (1.15–3.2, 0.4–1.0). This study provides a more convenient and accurate method for calculating conversion coefficients (BEF and BCEF), especially when only Rcs data is available.

Radar Detection Performance via Frequency Agility Using Measured UAVs RCS Data

Radar Detection Performance via Frequency Agility Using Measured UAVs RCS Data

Radar Cross Section Analysis of Two Wind Turbines via a Novel Millimeter-Wave Technique and Scale Model Measurements

A novel, low cost, highly accurate, millimeter-wave RCS characterization method is developed and presented in this paper. In order to develop and verify the validity of the proposed method, full scale models and scale models of the horizontal-axis wind turbine (HAWT) and Crossflow turbines have been simulated and compared for a case study. The RCS of a scaled Crossflow turbine model was then experimentally verified using the novel method presented at frequencies of 76-81GHz. The proposed method utilizes the AWR1843BOOST evaluation board and DCA1000EVM real-time high-speed data capture card from Texas Instruments. To the best of the authors’ knowledge, this is the first RCS analysis of a scaled model performed at the mm-wave frequencies of 76-81GHz. This novel method is quick, simple, and fully automated, while maintaining high accuracy. Additionally, this has been achieved at a low cost using commercially available off the shelf parts. Good agreement was observed between the simulated and experimental results. Comparing the RCS data of the two turbines, it appears that the Crossflow turbine geometry offers a lower RCS and Doppler spectrum contamination as compared with a traditional horizontal axis wind turbine structure. These results are necessary and useful in allaying the increasing concerns regarding wind turbine radar interference, which have appeared as a result of the widespread adoption of wind power generation in recent years.

Maritime Multiple Moving Target Detection Using Multiple-BDS-Based Radar: Doppler Phase Compensation and Resolution Improvement

With the realization of global navigation satellite system (GNSS) completion, GNSS reflectometry (GNSS-R) has become increasingly popular due to the advantages of global coverage and the availability of multiple sources in terms of earth remote sensing. This paper analyzes the Beidou navigation satellite system (BDS) signal reflection detection of multiple satellites and multiple moving targets under multiple-input and multiple-output (MIMO) radar systems and proposes a series of methods to suppress multiple Doppler phase influences and improve the range detection property. The simulation results show the restored target peaks, which match the RCS data more accurately, with the GNSS-R Doppler phase influence removed, which proves the proposed method can improve target recognition and detection resolution performance.

Compressive sensing‐based two‐dimensional scattering‐center extraction for incomplete RCS data

Compressive sensing‐based two‐dimensional scattering‐center extraction for incomplete RCS data

A Study on the Solutions of Guided Missile Attacks using 3-D RCS Data of Maritime Ship

A Study on the Solutions of Guided Missile Attacks using 3-D RCS Data of Maritime Ship

Arbitrary size ratio canonical object classification based on Convolutional Neural Network

Based on the research of radar target characteristics and the need for classification and recognition of targets, this paper presents the application of convolutional neural network(CNN) to the classification of canonical objects with non-fixed size ratio. First, the whole-angle RCS data of the canonical objects is preprocessed, then it is used for training CNN network, thus, the classification and recognition of five kinds of canonical objects with arbitrary size ratio(i.e., plate, dihedral, trihedral, cylinder, top-hat) are realized. The training accuracy is 99% and the validation accuracy is 97% on the data set simulated on canonical objects with different size ratios. This study can provide a research foundation and reference for the classification and recognition of complex objects.

유도탄 조우 시나리오를 고려한 W-대역 밀리미터파 탐색기의 지상 표적 식별을 위한 1차원 산란점 추출에 관한 연구

In this paper, we introduce a method of selection for the optimal transmission polarization of a W-band seeker through the extraction of the one-dimensional scattering center of a ground tank target. We calculated the surface scattering and edge scattering using the shooting and bouncing ray tracing method of the CST A-solver. Based on 4-channel RCS data, using the one-dimensional RELAX algorithm, which is a kind of spectral estimation technique, scattering centers of ground targets were extracted. According to the changes in the polarization state and look angle, we compared and analyzed the scattering center results. Through simulation, we verified that the scattering center results can be applied when feature vectors are used for target recognition.

A Novel Anti-Stealth Technique Based on Stratospheric Balloon-Borne Radar in Heterogeneous Environments

AbstractRadar cross section (RCS) of a stealth target model like F-117A can be improved by multichannel stratospheric balloon-borne bistatic radar at higher aspect angle. The potential problem is that the stealth target may produce range walk in clutter heterogeneous environments, thus it is difficult to determine the range ambiguity under quadratic range cell migration (QRCM). In this paper, a novel detection technique known as hybrid modified fractional-radon Fourier transform (MFrRFT) and knowledge-aided space–time adaptive processes (KA-STAP) is proposed to impact this kind of problem simultaneously. KA-STAP is applied to suppress the non-homogeneous clutter in the received data, and MFrRFT is used to eliminate the QRCM along with the second-order keystone transform (SOKT), so as to estimate the range ambiguity and compensate the stealth target’s range walk. The hybrid MFrRFT/KA-STAP scheme is simple and applicable to the small RCS of fast stealth target with a long-time coherent integration. Finally, to achieve high accuracy of locating stealth target, a non-parametric detection technique based on Legendre orthogonal polynomials is applied to reconstruct the probability density function (pdf) of real RCS data predicted by physical optics (PO) approximation method.

Sparse 복원 알고리즘을 이용한 HRRP 및 ISAR 영상 형성에 관한 연구

Abstract In this paper, we introduce a sparse recovery algorithm applied to a radar signal model, based on the compressive sensing(CS), for the formulation of the radar signatures, such as high-resolution range profile(HRRP) and ISAR(Inverse Synthetic Aperture Radar) image. When there exits missing data in observed RCS data samples, we cannot obtain correct high-resolution radar signatures with the tra-ditional IDFT(Inverse Discrete Fourier Transform) method. However, high-resolution radar signatures using the sparse recovery algorithm can be successfully recovered in the presence of data missing and qualities of the recovered radar signatures are nearly comparable to those of radar signatures using a complete RCS data without missing data. Therefore, the results show that the sparse recovery al-gorithm rather than the DFT method can be suitably applied for the reconstruction of high-resolution radar signatures, although we co-llect incomplete RCS data due to unwanted interferences or jamming signals.Key words: Sparse Recovery Algorithm, BPDN, Radar Signal Model, ISAR Image, HRRP lmn@ opqUr@Usmn,tK /IR uA Revised January 2, 2014 ; Accepted January 28, 2014. (ID No. 20131125-116)Corresponding Author: Kyung-Tae Kim (e-mail: kkt@postech.ac.kr)

Dynamic RCS Statistic Characterization of Stealth Aircraft Using Complete Lognormal Distribution

RCS of aircraft varies with time or radar wave incident angle without regular pattern during its movement. It is necessary to analyze RCS variation using statistic items or models. The research objects of existing literatures are mostly conventional aircrafts. Research on stealth aircraft is poor. A typical stealth aircraft is selected as the research object in this paper. Its dynamic RCS data under different flying attitudes are evaluated by the combination method of physical optics and physical theory of diffraction. And Swerling type Ⅰ and type Ⅲ distribution, chi-2 distribution and lognormal distribution are applied to analyze the statistic characteristics of the RCS datasets. As the ratio of mean to median of stealth target can be less than 1, the complete form of lognormal distribution model is proposed. Lognormal distribution model can provide a better approximation of the RCS datasets than the other models concerning the model errors and the results of fitting goodness test.

Design of Analysis Software for Measured RCS Data

Radar cross section is an extremely important parameter in narrowband radar application for space target detection, tracking, and identification, as well as for the purpose of threat assessment. An analysis algorism, together with related software for measured RCS data has been developed to extract information from the original data. Some analyzing methods for measured RCS data were introduced. The playback visual simulation process and data processing were elaborated, so as to handle the processing of software program. Finally the software running results were analyzed. The experiment results showed that the software could be used for the issue of analysis of measured RCS data in a reliable and systematical way. As a result, it provides us with a strong guarantee for space surveillance.

On radar accuracy using beam wave in random media

The accuracy of radar detection is measured in this paper through comparing the laser radar cross-section (LRCS) to RCS data for plane-wave incidence in free space. This is to study the performance of backscattering enhancement from conducting targets with finite size. LRCS is calculated using beam wave incidence propagating in a random medium. Targets are of large size with relatively complex cross-sections. E-wave polarization is assumed for incident waves in continuous random media with different spatial coherency.

Global Scattering Center Model Extraction of Radar Targets Based on Wideband Measurements

The scattering center model represents the scattering characteristics of radar targets at high frequencies by a set of point scatterers. Such a model is useful in scattering analysis, data compression and target recognition. We propose a methodology to extract the scattering center model from wideband measurements at sparsely distributed aspect angles. It exploits the regular variation in the ID projective location and the slow variation in the scattering coefficient of stable scattering centers at adjacent aspects, and greatly cuts down the original data amount compared to other methods. The extracted model contains the stable scattering centers of the target and is effective in a large angular extent. It can be used to reconstruct the target signatures such as RCS data and radar images at any aspect in this angular extent and at any frequency in or near the original measuring band. Examples using both simple and complex targets demonstrate the validity of this technique.

Adaptive sampling bicubic spline interpolation method for fast calculation of monostatic RCS

AbstractIn this article, an adaptive technique combined with the bicubic spline interpolation method is proposed to efficiently calculate the scattering from electrically large objects. The bicubic spline interpolation method is used to approximate the 2D monostatic RCS data on a set of nonuniform sampling nodes. The adaptive technique is employed to generate new sampling points automatically by using a coarse‐to‐fine hierarchy. Compared with some conventional extrapolation/interpolation methods, such as asymptotic waveform evaluation (AWE) method, our method can avoid calculating derivatives at each control point by using spline technique. Numerical results demonstrate that the novel method proposed in this article is able to approximate the 2D RCS data with high accuracy and efficiency. © Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1851–1857, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23540

Radar Cross Section of Simple and Complex Targets in the C-band: A Comparison between Anechoic Chamber Measurements and Simulations

In order to validate RCS measurements performed in an anechoic chamber, experi- mental results are compared with simulations made using a commercial electromagnetic software package. The experimental part of this work was performed inside an anechoic chamber, with the radar operating in the C-band (6GHz). Two metallic targets, a cylindrical body with four square flns and a section of an air-to-air missile, were used for the RCS measurements. In order to improve the accuracy of the experimental data, an active noise suppressing system, based on the principle of phase cancellation, was used. The simulation software FEKO was used to calculate the RCS of models of these two targets. The comparison of simulations and experimental data shows good agreement between them, validating the experimental methods used in the collection of RCS data, as well as the results obtained with the simulation software.

Two-sphere interference in RCS measurements and imaging

New RCS data on two spheres in rotation are presented. From the simple geometry, the results allow us to verify both the cross-range and down-range distance scales in imaging. With the known RCS of the individual spheres, we find that it is feasible to calibrate the image RCS scale to dBsm, provided care is taken to mitigate the shadowing and sidelobe effects.

誘導加熱法を用いた高強度合金鋼の急速焼結（第２報）

To study rapid sintering by induction heating, we used high strength-alloyed steel powder, completely alloyed powder of 0.55 mass%Ni-0.6mass%Mo-0.2mass%Mn-0.5mass%C-bal.Fe. In this rapid sintering, evolution of a Martensitic or Bainitic structure in the matrix was examined to play a very important role. Thus, the substantial controlling factors were the holding time and cooling time for grain boundary diffusion. Experimental results showed that this process required a higher sintering temperature compared with the continuous furnace, but the sintered materials gained a higher radial crushing strength (R.C.S) by changing the holding time and cooling time. Although, the holding time were only 3-4minutes in the present process, and high strength-alloyed steel was also obtained to a very good size accuracy when putting it in practical use industrially. The optimum condition appeared to be a sintering temperature of 1573 K and holding time 120-180s with a heating time of 65s; the RCS data was attained about 1200 MPa.

Assessment of orbital debris size estimation from radar cross-section measurements

MIT Lincoln Laboratory has conducted a measurement program for man-made orbital debris since 1991 in response to NASA's need to characterize the orbital debris population and facilitate manned spaceflight activities. The primary sensors used in that effort are the Haystack and Haystack auxiliary (HAX) radars located at the Lincoln space surveillance complex (LSSC) in Westford, Massachusetts. This paper will describe the results from a new effort conducted at LSSC, the objective of which is to assess the variability in NASA's current procedure for determination of size from radar data. RCS data have been acquired on 39 NASA-selected resident space objects (RSO). Results are also compared to the size estimates from the FPS-85 radar, an asset of the Space Surveillance Network.