This paper summarizes our recent research progress on three issues: how to link the coherence matrix and entropy directly with the measurement of co-polarized and cross polarized backscattering in fully polarimetric SAR imagery, how to invert DEM by using only one-flight fully polarimetric SAR
image, and how to automatically detect the surface change by using multi-temporal SAR images.
Polarimetric scattering, SAR, Characteristic information, Classification, DEM, Multi-temporal detection
Electromagnetic scattering and propagation in natural environment plays important role for defense hi-technology, such as radar surveillance, missile guidance, and target tracking etc. This paper briefly reports our recent research on some issues, e.g. numerical simulations of bistatic scattering from the ship on and flying target over wind-driven oceanic surface, the land-ocean clutters and Doppler shifts for interference of missile guidance, and some applications of microwave remote sensing technology such as SAR, SSM/I to defense technology.
China has launched its Fourth spaceship SZ-4 in Dec. 30, 2002 in which the main remote sensing sensor is the Multiple Model Microwave Remote Sensor (M3RS). In this paper first the properties of M3RS are introduced briefly. Second, the preliminary application results for M3RS are discussed in detail.Third, the evaluation of the M3RS(model of Altimeter, Radiometer and Scatterometer) was a key activity SZ-4 project. This paper summarizes the primary achievements and limitations of the evaluation process.
Interferometric synthetic aperture radiometry is a relative new technique in the area of microwave earth observation to measure the brightness temperature distribution of the earth. It can enhance the spatial resolution of the passive microwave remote sensing effectively. Steady progresses of this technology have been achieved in both one dimensional and two dimensional cases since 1990' s. In this paper, the technique development of the interferometric synthetic aperture radiometry in the past ten years was reviewed. The imaging principle of the aperture synthesis was introduced. Both of the two most common means of the aperture synthesis, one dimensional and two dimensional, were described. Another aperture
synthesis means based on antenna array rotating was also described as the latest progress. Then the existing and proposed instruments were reviewed, including ESTAR, 2D-STAR, GeoSTAR from the US,MIRAS of the ESA mission SMOS, HUT-2D developed by Helsinki University of Technology, and the C-band and X-band systems developed by Center for Space Science and Applied Research, Chinese Academy of Sciences, etc. Finally, the application prospect of the interferometric synthetic aperture technology was discussed, especially in the area of earth observation, space exploration, reconnaissance and some security imaging application.
This paper summarizes the theoretical and experimental work in remote sensing of atmospere and oceanography using GPS fistly. The philosophy and some experimental results for the GPS method are presented secondly. Then the GPS method with the traditional remote sensing method are compaered.Finally, there are some discussions in the paper as suggestions for the development of space microwave remote sensing and the applications in the second generation satellite navagation system in China.
The optimization of polarimetric contrast enhancement (OPCE) is one of important problems in radar polarimetry. This problem is to find the optimal polarizations for maximizing the ratio of the powers from a target and clutter. In this paper, we summarize several models and algorithms on OPCE for various cases.
There are many close contacts between the radiowave environment and microwave remote sensing technology. Microwave remote sensing is paid more attention by remote sensing field for its all weather,all time, strong permeability, plenty of multi-band and polarization information, especially the ability of microwave imaging and information interpretation (explanation, inversion, classification, recognition etc.) is improved and the application of microwave remote sensing is developed rapidly with the development of theory and technology, previous disadvantage of microwave information has been improved greatly. The roles of radiowave environment in microwave remote sensing are in two areas, the first is as the target or object for microwave remote sensing, for example the ground information; the second is to affect the target of remote sensing with the process. This paper analyses the factors or conditions of radiowave environment and discuss the methods and models of geometry and physics, which aim at the effects of radiowave environment in microwave remote sensing.
The surface soil moisture is a quantity resulting from the water and energy exchanges at the land-surface/atmosphere interface. Measuring this variable has potential application in hydrology and meteorology. Passive microwave remote sensing techniques have great potential for providing estimates of soil moisture with good temporal repetition on a daily basis and on a regional scale (～10 km).Compared with optical and thermal-infrared sensors, although passive microwave measurements are of lower spatial resolution than optical and infrared measurements, they are less influenced by solar illumination, aerosols,and clouds, and they are responsive to different dynamic ranges of vegetation structure and biomass.
Compared with active microwave sensors, the passive microwave systems include frequent coverage, low data rates, simpler data processing. However, the effects of vegetation cover, soil temperature, snow cover, topography, and soil surface roughness also play a significant role in the microwave emission from the surface. Different soil moisture retrieval approaches have been developed to account for the various parameters contributing to the surface microwave emission. In this paper, approaches for monitoring soil moisture using passive microwave remote sensing were discussed and compared, especially the retrieval approaches which will have to be used in the future operational application.
We introduce in this paper the Scatterometer mode of Multimode Microwave Sensors on board Chinese Shenzhou-4 unmanned spacecraft launched on Dec. 29, 2002. We first introduce the system components, characteristics and airborne experiment simply, and then, initroduce the data processing and system simulation in detail. We also present the measured wind field during flight experiment and the radar backscattering coefficients over the Amazon rain forest.
With the development of space exploration, synthetic microwave remote sensor is playing an more and more important role in the field of microwave remote sensing. A synthetic microwave remote sensor, also can be named multi-mode micowave remote sensor(MRS), is composed of several remote sensing subsystems which can work together fluently and share as many resources as possible., and the key is its control and communication system. In this paper, the control and communication system of a remote sensor, the main payload with a spaceship, will be introduced in detail.
The multi-frequency microwave radiometer on“SZ-4”spaceship is the first air-to-ground passive microwave sensor developed in China. In this paper, firstly, the performance parameters and indices of the radiometer are introduced in brief. Secondly, the measured data of ground objects are given and analyzed.On the basis of the data, we analyze the stability of the microwave radiometer. In addition, water content in atmosphere and the surface temperature regression model of desert are gotten from the data. Finally,compare the analysis results from the microwave radiometer mentioned above and other space-borne microwave radiometers. From the comparing results, we can come to a conclusion that the data from the microwave radiometer on“SZ-4”spaceship are available.
SZ-4 main payload-multi-mode microwave remote sensor is the first spaceborne microwave remote sensor in China. It is composed of an altimeter, a scatterometer and radiometers. In the system,the altimetry, scatterometry and radiometry functions are integrated technically. A lot of data are acquired during SZ-4 orbital experiments. The orbital experiments are successful. In the paper, the main characteristics are listed based on development requirements. The principle, block diagram, control system and system tests of multi-mode microwave remote sensor are introduced. The orbital experiments are summarized and conclusions are put forward.
The real-time signal processor' s system structure and the algorithm flow of real-time imaging for air-borne SAR is introduced in the paper. The high resolution SAR images is given from SAR data obtained from the air-borne platform. This show the system is reliable.
The speech channel is an important tool for communications among people in the engine room and passenger compartment of training aircraft machines. In this paper, a smart and digitized airborne communication system based on HDLC protocol is presented .The operation principle of this system is introduced and the design of software and hardware is described in detail as well. The communication system can realize the conversation among principal driver, An occasional driver, coach, ground service attendant and ground radio station. The control signals in the ground and trainer aircraft can also be monitored and transmitted in real time.
The radar altimeter, the microwave scatterometer, and the Multi-frequency radiometer are the main payloads for China' s Oceanic Dynamic Environment Mission (HY-2). This paper describes the specification and parameters of the radar altimeter and microwave scatterometer. Some details about the design of these two instruments are also presented.
The antenna subsystem of the multi-mode microwave remote sensor of the SHENZHOU spacecraft is a breakthrough of aerospace antenna technology of China. This paper presents the operating mode, design know-how and system confirmation of the antenna. The detailed performance of the antenna is also given.
This paper gives the integrated(mechanical, electrical, and thermal) design procedure of the antenna subsystem of multi-mode microwave remote sensor. The assembly and deformation measurement of the antenna has been implemented by combining optical methods and computer technology.
In this paper the system composing, operating modes and the method of motion compensation of a high-resolution microwave remote sensing system is described, and some experimental results are introduced.
Rapidly exploiting SAR data through computer programming is demanded. The purpose of this research is to present a basic study of rapid information extraction in full SAR scene image of high resolution. The idea is coming from that some ground features such as rivers, lakes, main roads and urban are sustained in a short period of time. So the information such as location, length, and size of those features stored in database in advance are used as the tool of region of interest (ROI) or the criterion of discrimination in order to direct the computer to adopt adaptive method to analysis SAR images.
Microwave emission and temperature retrieval problems have been studied with data of ShenZhou-IV Spaceborne Multiple Band Microwave Radiometer. The data standard deviation of each track is about 2.5 K, which is in the same level of SMMR above the same site. The study shows that the Radiometer has been operating stably. The brightness temperature observed in low-frequency channels is higher than that in high-frequency channels. This phenomenon is closely related to microwave sampling depth when it is compared with other data such as meteorological observation and optical remote sensing data. The observed brightness temperature has good correlation with surface parameters by correlation
analysis between observed brightness temperature of each channel and surface temperature.
A new method is proposed for studying the polarimetric backscattering coefficients from a soybean canopy. This method combines the branch model, which emphasizes the significance of vegetation architecture and coherent effect, and the CP-PACT model, which adopts antenna array concept to account for the inter-scatterer interaction, an appropriate technique to be applied to agricultural crops like soybean where semi-periodic plant arrangement is the norm of agricultural practice. Moreover, in relating the Eulerian angles that describe the orientation of an axissymmetric scatterer to the elation and azimuth angles of the spherical coordinate system, the new association suggested in this study makes more physical sense.The effectiveness of this proposed method is validated by good agreement between the predicted backscattering coefficients and measurement data.
This paper presents a dual-polarized X-band airborne real-aperture radar (RAR) that is suitable for submesoscale ocean imaging and research. The airborne RAR was flown during the Chesapeake Bay Outflow Plume Experiment (COPE) in 1996, 1997 and 1999. Sample results from the COPE experiment are presented here to demonstrate that an inexpensive airborne RAR constructed using commercial off-the shelf products can be a powerful and cost-effective remote sensing tool for studying submesoscale oceanic processes and features such as oceanic slicks, internal waves and estuarine outflow plumes and their associated fronts. The effectiveness of airborne RAR in these applications is due to its unique capabilities
of high sampling frame rate, low cost real-time image processing and large incidence angles. System trade off study is also carried out to determine the optimal radar configurations and limitations of the airborne RARs in imaging the ocean surface.
The multi-channel microwave radiometer ( RAD) on-aboard SZ-4 spacecraft was the first spaceborne microwave radiometer in China which launched at the end of 2002. In order to apply the brightness temperatures obtained by RAD, We developed an antenna pattern correct ( APC) algorithms for deriving brightness temperatures from calibrated antenna temperatures for all RAD frequencies and incidence angles. A set of statistical algorithms of retrieving sea surface temperatures ( SST ) , wind speeds (WS) ,volume watervapor contents (WV ) above the global ocean were put forward. We compared the retrievals with geophysical products of TMI. Rms of 2.13℃ for SST, 0.44m/s for WS, and 2. 80mm for WV were obtained from comparing respectively . At the end of the paper, we gave a summary of comparisons. After deleting the matched data with rain, i.e, volume liquid contents above0.3mm, we derived SST, WS, and WV withrms of 1.40℃、0.35m/ s and 2.71mm, respectively, which showed that rain has great effects on the retrieving these parameters, especially on SST retrievals. Genarally , Brightness temparetures by vicarious external calibration can be used for re rieving SST, WS, and WV at certain accuracy.
The application of high-resolution synthetic aperture radar (SAR) images from aerial and satellite sensors challenges the researchers for new and effective interpretation tools. Although most of the main axes in the road network may be detected by a skilled human observer looking for dark or bright linear structures, automatic detection remains a difficult task. In this paper, we proposed a new simple approach to extract main road network in high-resolution SAR images automatically. The approach is based on three steps. The first step is pre-filtering the initial SAR images by using a two-way thresholding process in order to discard uninteresting parts of image. In the second step, the results of the first step are input and use the Hough Transform to identify the roads respectively. The last step is based on a feature fusion technique. The road networks detected are combined with the fusion operators. We show the improved results from some examples. It is proved that this approach is effective for the straight highways
in high-resolution images.
Based on the collection of plentiful terrestrial basalts and anorthosites, the authors prepared nine lunar soil simulants and made them respectively into 0.8 g/cm3, 1.0 g/cm3, 1.2 g/cm3, 1.4 g/cm3and1.6 g/cm3five densities each; then measured their relative dielectric constants over the range of 0.5～20 GHz with open-ended coaxial line model on the HP8722C Network Analyzer and conducted statistical regression analyses of the measurement data. The result shows that density, frequency and composition have clearly different influences upon the relative dielectric constants of the lunar soil simulants, density has the strongest effect on the relative dielectric constants, frequency weaker, and composition the weakest. The real parts of the relative dielectric constants increase linearly with density and decrease linearly with frequency; the imaginary parts of the relative dielectric constants increase linearly with whether density or frequency over the range of 0.5～10 GHz, but become irregular at frequencies higher
than 10 GHz. Effect of composition on the relative dielectric constants seems very complicated; both do not follow a simple function relation to a great extent.
With the resolution of SAR image is improving, the inner structure of residential area shows more complex in high-resolution SAR images than low ones. An approach is proposed to extracting residential area based on SAR texture features extracted from the Gray Level Co-occurrence Matrix
(GLCM). Firstly, six texture features such as energy, entropy, contrast, variance, correlation, and inverse difference moment are investigated. Secondly, the three GLCM parameters: window size, step and angle are decided. Thirdly, the feature vector is reduced from six to two. Then an unsupervised analysis is applied to the data to extract the residential area. Finally the small areas are deleted, and morphological operators are applied to adjust the sketch of the extracted area. The proposed method has been tested by using airborne SAR data at 3 m resolution.
Based on deeply analyzing wave-current interaction equations and radar backscattering model of ocean surface, it developed a calculating model of radar backscattering coefficient caused by wave-current interaction on ocean surface.Then the model is compared with the well known Alpers' s model through numerical test on calculating radar backscattering coefficient perturbation caused by ocean surface non-even current fields.Furthermore it provided the statistical and analyzing results of the two models' coherence degree. The results show that the two models are coincident.Thus this paper' s model can be regarded as a numerical model to study radar' s ability for detecting ocean surface non-even current fields.
The Wind retrievals produced from microwave scatterometer are affected by the presence of rain.Quantifying the effect of rain on scatterometer wind measurements is important for increasing the applications of satellite scatterometry under extreme weather conditions such as those found in tropical storms and hurricanes/typhoons. A set of microwave remote sensing data collected with UMass Imaging Wind and Rain Airborne Profiler (IWRAP) during the 2002 Atlantic Hurricane Season has being analyzed by the Institute of Remote Sensing and Geographic Information System (IRSGIS) at Peking University (PKU), in collaboration with the Microwave Remote Sensing Laboratory (MIRSL) at University of Massachusetts (UMass), NOAA Hurricane Research Division (HRD) and NOAA National Environmental Satellite Data and Information Service (NESDIS). This paper presents preliminary results of precipitation effect on microwave scatterometry wind estimates at Ku band. The results show that microwave scatterometer underestimates the wind speed by up to 10 m/s for rain rate condition of 12 mm/hr and wind speed condition of 25 to 30 m/s for Ku bands, and up to 20 m/s when rain rate is higher than 16 mm/hr.
SZ-4 radar altimeter, which is the first China' s spaceborne radar altimeter launched on Dec. 30th2002, had obtained plenty of scientific data in terms of the pre-designed operational modes. The operational models, the real time track processing, the debug on orbit, and the measurement results are discussed in this paper.
The multi-channel microwave radiometer (RAD) on-aboard SZ-4 spacecraft was the first spaceborne microwave radiometer in China which launched at the end of 2002. In order to calibrate quantatively its performances and responses to the given targets microwave radiation, and validate the accury of its products, we carried on an in situ test which was conducted on Liuhua 11-1 oil platform from Dec 27,2002 to Jan 9, 2003. We employed a multiband microwave radiometer (MMR) operating at 6.6,13.9,19.35,22. 235, and 37. 0GHz, in total power mode. By rotating the horn antenna, we obtained bightness temperatures in vertical polarization, horizontal polarization, positive 45 degree linear polariztion and negative 45 degree linear polarization.This paper we first gave a general review of the experiment, then expanded the results measued by the senors, and anylysed in detail atmosphere effects on the in situ measurements for extrapolating the surface brightness temperature to the level at RAD antenna. Because the surface measurements were all collected at a certain point, while radiation RAD received were from all direction weighted by its antenna patterns, we developed an algorithm of relating boresight brightness temperature at the surface to the weighted antenna temperature at RAD antenna output. Finally, we illustrated the MMR results corrected after applied the algorithm and compared with co-located RAD measurements.
Based on the High Resolution SAR system experiments. Some problem that influenced the quality of image was discussed. Since The INS did not meet the need of Error Compensation, Doppler parameters (fdc,fdr) was obtained by SAR Raw data to compensate the LOS error and phase error. Theresidual Error was compensated by PGA method. Then the high quality of SAR image was obtained.
Abstract:The principles and performance of an experimental Return Signal Simulator(RSS) with its means of testing and calibration for radar altimeter were given. By using the RSS, the full system ground-based test and calibration experiments were performed for the "Shenzhou IV" spacecraft altimeter. The results show that the feasibility of the RSS means for radar altimeter test and calibration, and the prelaunch dynamic performance of the“Shenzhou IV”spacecraft radar altimeter are validated effectively.
This paper analyzes some major parameters affecting the performance of digital Chirp implemented by waveform-storage DDS approach. At the same time, compares the advantages and disadvantages between the waveform-storage DDS approach and another DDS approach of phase
accumulation. Computer simulations with MATLAB/SIIMULINK show that, sampling frequency,resolution of the Digital-to-analog-converter, low pass filter and I/Q modulator affect the output Chirp spectrum in different aspects. The developed software based on MATLAB/SIIMULINK can provide an analyzing, design and optimization platform for DDS digital chirp.
This paper presents two Adaptive Kalman Filter Algorithms to retrieve the 3-D hurricane wind vectors. The algorithms are developed for the measurements of UMass Imaging Wind and Rain Airborne Profiler which was installed on the NOAA WP-3D research aircraft during the 2002 NOAA Hurricane Ocean Winds Experiment. Performance analyses of the algorithms are presented in this paper using simulation. Preliminary results of the actual 3-D wind estimates using the chosen algorithm are obtained and compared with simultaneous and independent wind vector measurements by GPS dropwindsondes,surface wind speed measurements by a microwave radiometer and flight level wind vector measurements.
FY3 is new generation polar orbit meteorological satellite of China plan to launch in 2006. There is total of 11 different remote sensing sensor onboard it, design to get the geophysical parameters of atmosphere, land, and ocean surfaces at the same time all day and night and in all weather conditions. The MWRI is a 10-channel five-frequency linearly polarized, passive microwave radiometer imager system onboard the FY3, which measures atmospheric, ocean, and terrain microwave brightness temperatures at 10.65, 18.7, 22.3, 36.5, and 89 GHz. In this paper, in order to derive surface temperature and soil moisture from the MWRI data, a new developed microwave RT model, AIEM was used to simulate the
microwave emission characteristic of bare soil, and an new surface soil moisture inversion algorithm was established, which is only need the 10.65GHz V and Hchannel data. Applying the algorithm to AMSR-E orbit data, which is very similar with the FY3/MWRI, the daily globe soil moisture and surface temperature distribution was derived.
Test of nonlinearity of time series is very important for nonlinear time series analysis and study of chaotic dynamics. This paper discusses various methods of test of nonlinearity of time series. Real-life sea clutter data are tested with the IAAFT method combined with redundancy. It is concluded that sea clutter comes from a nonlinear process by analyzing results of test. So nonlinear methods should use to study
characteristic of sea clutter.
The paper focus on the study of several typical clutter suppression techniques for multi-channel SAR: Displaced Phase Center Antenna (DPCA), Along Track Interferometry (ATI) and Space Time Adaptive Processing (STAP) techniques. In the paper, it has been discussed that application of DPCA and ATI in the complex image domain for moving target detection in airborne single-antenna SAR real data as well as application of STAP in the space-doppler domain. In the end, some experimental results have been presented.
The paper analyses the characters of ground moving targets and researches several moving targets detection algorithms such as Displaced Phase Center Antenna(DPCA), Along-track interferometry(ATI), Space-time adaptive processing(STAP) and Deconvolution used in Synthetic Aperture Radar
(SAR). It describes every algorithms and provides some diagrams. In the last, the paper computes motion parameters when using ATI to detect moving targets.
