• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제14권7호
• /
• pp.2879-2890
• /
• 2020

In this paper, we study the estimation of angle, range and polarization parameters of a bistatic polarization sensitive frequency diverse array multiple-input multiple-output (PSFDA-MIMO) radar system. The application of polarization sensitive array in receiver is explored. A signal model of bistatic PSFDA-MIMO radar system is established. In order to utilize the multi-dimensional structure of array signals, the matched filtering radar data can be represented by a third-order tensor model. A joint estimation of the direction-of-departure (DOD), direction-of-arrival (DOA), range and polarization parameters based on parallel factor (PARAFAC) algorithm is proposed. The proposed algorithm does not need to search spectral peaks and singular value decomposition, and can obtain automatic pairing estimation. The method was compared with the existing methods, and the results show that the performance of the method is better. Therefore, the accuracy of the parameter estimation is further improved.

• 전기학회논문지P
• /
• 제64권2호
• /
• pp.92-95
• /
• 2015

Capacity reflecting effects of quantized feedback information is evaluated through computer simulation for practical implementation of polarization angle estimation and compensation. In the dual-polarization antenna case, evaluated capacity values varies more than four times depending on accuracy of the polarization angle estimation and compensation. Using 6-bit the quantized feedback information, we can achieve 96.8 percentage of the capacity of the perfect feedback information case.

• 대기
• /
• 제24권3호
• /
• pp.365-378
• /
• 2014

The limits of S-band dual-polarization radars in Korea are not reflected on the recent weather forecasts of Korea Meteorological Administration and furthermore, they are only utilized for rainfall estimations and hydrometeor classification researches. Therefore, this study applied four merging methods [SA (Simple Average), WA (Weighted Average), SSE (Sum of Squared Error), TV (Time-varying mergence)] to the QPE (Quantitative Precipitation Estimation) model [called RAR (Radar-AWS Rainfall) calculation system] using single-polarization radars and S-band dual-polarization radar in order to improve the accuracy of the rainfall estimation of the RAR calculation system. As a result, the merging results of the WA and SSE methods, which are assigned different weights due to the accuracy of the individual model, performed better than the popular merging method, the SA (Simple Average) method. In particular, the results of TVWA (Time-Varying WA) and TVSSE (Time-Varying SSE), which were weighted differently due to the time-varying model error and standard deviation, were superior to the WA and SSE. Among of all the merging methods, the accuracy of the TVWA merging results showed the best performance. Therefore, merging the rainfalls from the RAR calculation system and S-band dual-polarization radar using the merging method proposed by this study enables to improve the accuracy of the quantitative rainfall estimation of the RAR calculation system. Moreover, this study is worthy of the fundamental research on the active utilization of dual-polarization radar for weather forecasts.

• 대한원격탐사학회지
• /
• 제27권6호
• /
• pp.729-741
• /
• 2011

Wind speeds have long been estimated from C-band VV-polarized SAR data by using the CMOD algorithms such as CMOD4, CMOD5, and CMOD_IFR2. Some SAR data with HH-polarization without any observations in VV-polarization mode should be converted to VV-polarized value in order to use the previous algorithms based on VV-polarized observation. To satisfy the necessity of polarization ratio (PR) for the conversion, we retrieved the conversion parameter from full-polarized SIR-C SAR image off the east coast of Korea. The polarization ratio for SIR-C SAR data was estimated to 0.47. To assess the accuracy of the polarization ratio coefficient, pseudo VV-polarized normalized radar cross section (NRCS) values were calculated and compared with the original VV-polarized ones. As a result, the estimated psudo values showed a good agreement with the original VV-polarized data with an root mean square error by 0.99 dB. We applied the psudo NRCS to the estimation of wind speeds based on the CMOD wind models. Comparison of the retrieved wind field with the ECMWF and NCEP/NCAR reanalysis wind data showed relatively small rms errors of 1.88 and 1.91 m/s, respectively. SIR-C HH-polarized SAR wind retrievals met the requirement of the scatterometer winds in overall. However, the polarization ratio coefficient revealed dependence on NRCS value, wind speed, and incident angle.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2003년도 하계종합학술대회 논문집 I
• /
• pp.609-612
• /
• 2003

For combating multipath fading in wireless radio environment, diversity schemes is useful. In this paper, for performance improvement of polarization diversity system, we analyzed a two-branch polarization diversity at the receiving end of a mobile link when the transmitter emits a circularly polarized wave. And In order to calculate the correlation coefficient considering the XPD(cross polarization discrimination) between the received signals for the two diversity branches, a simple theoretical model of circular polarization diversity is adopted and calculate correlation coefficient. From the analysis results, it is seen that the correlation coefficient of circular polarization diversity evaluated by the XPD is less than that of vertical polarization diversity. And also, we designed and fabricated circular polarization diversity system with microstrip antenna. we analyzed data measured in indoor NLOS environment using fabricated circular polarization diversity system. From the measurement results, it is clearly seen that the diversity effect of circular polarization diversity system is higher 3dB than vertical polarization diversity system.

• 한국수자원학회논문집
• /
• 제47권9호
• /
• pp.801-812
• /
• 2014

본 연구에서는 합천댐, 회천 유역에 대하여 비슬산 이중편파 레이더를 이용하여 유역평균강우량을 각각 추정하여 지상 우량계의 강우량과 비교한 후 분포형 유출모형인 Vflo 모형을 사용하여 유출을 모의하였다. 유역평균 강우량 분석 결과 이중편파 레이더 변수를 사용한 결과 첨두우량 및 전체 강우량 값이 지상우량계 값과 근접하게 산정되었고, Vflo 분포형 모형을 사용한 유출모의 분석 결과 또한 이중편파 레이더 변수를 사용한 유출모의가 실제 유출량에 근접하였다. 이는 이중편파 레이더를 사용한 강우추정 및 유출모의가 기존의 수평반사도만을 사용한 단일편파 레이더보다 정확성을 높일 수 있는 방법이라고 판단된다.

• 한국수자원학회논문집
• /
• 제47권12호
• /
• pp.1227-1237
• /
• 2014

이중편파레이더는 강수의 형태를 구분하고 대기 중의 기상 현상뿐만 아니라 비강수에코에 대한 정보를 제공하기 때문에 보다 정확한 강수량 추정을 가능하게 한다. 그러나 수직, 수평으로 진동하는 전파를 송 수신하여 생성되는 이중편파레이더 관측변수들은 레이더 자체가 갖는 시스템적 관측오차를 포함하기 때문에 정량적 강수량 추정을 위해서는 이에 대한 보정이 필수적이다. 본 연구에서는 2차원 영상우적계(2-Dimensional Video Disdrometer, 이하 2DVD) 관측 자료를 이용하여 비슬산 이중편파레이더가 갖는 Z, $Z_{DR}$ 관측오차를 계산한 후, 관측오차 보정에 따라 강수량이 정량적으로 얼마나 개선되는지를 살펴보았다. 총 33강수사례에 대한 분석결과, Z는 약-0.3~5.5 dB, $Z_{DR}$는 -0.1~0.6 dB의 관측오차를 가지며, 대부분의 사례에서 Z와 $Z_{DR}$는 모의된 값보다 낮게 관측하였다. 관측오차를 보정한 전 후 산출된 이중편파레이더 강수량 추정값을 지상관측 강우강도와 비교한 결과, 평균 bias와 RMSE는 각각 1.54 mm/hr, 1.73 mm/hr로 보정 전의 1.69 mm/hr, 2.54 mm/hr 보다 감소함으로써 지상우량계 관측값 대비 레이더 강수량 추정값이 약 7~61% 향상되었다.

• Corrosion Science and Technology
• /
• 제8권5호
• /
• pp.193-196
• /
• 2009

For the estimation of uncertainty in potentiodynamic polarization resistance measurement, the type A uncertainty was measured using type 316 stainless steel in an acidified NaCl solution. Sensitivity coefficients were determined for measurand such as scan rate of potential, temperature of solution, concentration of NaCl, concentration of HCl, surface roughness of specimen and flow rate of purging gas. Sensitivity coefficients were large for the measurand such as the scan rate of potential, temperature of solution and roughness of specimen. However, the sensitivity coefficients were not the major factors influencing the combined standard uncertainty of polarization resistance due to the low values of uncertainty in measurements of the measurands. A major influencing factor was the concentration of NaCl. The value of type A uncertainty was 1.1 times the value of type B uncertainty, and the combined standard uncertainty was 10.5 % of the average value of polarization resistance.

• 대한원격탐사학회:학술대회논문집
• /
• 대한원격탐사학회 2005년도 Proceedings of ISRS 2005
• /
• pp.385-387
• /
• 2005

Polarimetric measurements of the sky radiation by the PSR-I000, which is the multi-spectral polarimeter developed by the Opt Research Corporation and has the same wavelength regions (443nm, 490nm, 565nm, 670nm, 765nm and 865nm) as the ADEOSII/POLDER sensor, have been carried out at the ground station in Kanazawa city, Japan from March to May. First of all, the wavelength dependency of degrees of polarization is examined and it is shown that degrees of polarization measured under the hazy dust cloud are lower than those measured in the clear sky and decrease as the wavelength increases. Next, a new method for estimating optical properties, such as the optical thickness, the number size distribution and the refractive index, of the Asian dust and the ground reflectance from degrees of polarization measured by PSR-I000 is described. Finally, this method is applied to polarization data acquired on April 15,2002. As a result, it is shown that our estimation algorithm provides a good result.

• 한국지구물리탐사학회:학술대회논문집
• /
• 한국지구물리탐사학회 2006년도 공동학술대회 논문집
• /
• pp.31-34
• /
• 2006

Laboratory experiment of polarimetric GPR measurement was conducted for the purpose of estimating subsurface inhomogeneity. Tow realization of inhomogeneous subsurface media were made by burying stone objects of different dimensions in homogeneous dry sand. Polarization ratio of cross polarization to co polarization data were examined to find their obviously distinguishable behavior.