This paper has reviewed the history of microwave remote sensing technology development during the past more than 50 years in worldwide and recalled the 30 years developing way of China microwave remote sensing development. The paper increasingly analyzes China microwave remote sensing present development and gives some national needs to this technique. The author provides the strategies for improving and some frontier technologies in future microwave development in China. The paper notes some important items which should be given more attention in future development.
Passive and active microwave remote sensing for the lunar regolith media are studied. Based on currently available digital elevation mapping (DEM) and some measurements of lunar regolith layer thickness at Apollo landing sites, a correspondence of the lunar regolith layer thickness to the lunar DEM is proposed to construct the global distribution of lunar regolith layer thickness. Using Clementine UVVIS multispectral data, the global spatial distribution of FeO+ TiO2content on the lunar regolith layer is calculated. Thus, dielectric permittivity of global lunar regolith layer can be obtained. Based on some measurements of physical temperature of the lunar surface, an empirical formula of physical temperature distribution over the lunar surface is presented. Based on aforementioned works, brightness temperature of lunar regolith layer in passive microwave remote sensing, which is planned for China' s Chang-E lunar project, is numerically simulated by a three layer model using fluctuation dissipation theorem.When these simulations as observations are obtained, an inversion approach of the lunar regolith layer thickness is developed. Because the penetration depth is small for the areas with high FeO+TiO2content,the emission contribution from underlying lunar rock becomes negligible at high frequency channels,
19.35 GHz and 37.0 GHz. Under this situation, the temperature of the top layer and the lower regolith can be inverted by the brightness temperature at these two channels using a two-layer model. Taking those points with high FeO+TiO2content along each latitude as the reference points, the temperature variation with the latitude of top layer and the lower regolith layer can be inverted. Then, taking the inverted temperature as a known parameter, the regolith layer thickness can be inverted by the brightness temperature at the channel 3.0 GHz. Numerical simulation and inversion approach in this paper make an evaluation of the performance for lunar passive microwave remote sensing, and for future data calibration
and validation.To explore the potential utilities of lower frequency radar pulse for lunar exploration, a theoretical model of lunar regolith layer and numerical simulation of polarimetric radar pulse echoes are developed in this study. The lunar regolith layer consist of the regolith layer with the randomly rough interfaces at the top and bittom of the regolith layer, and a layer of random discrete stones is laid over the lunar rock media. The time domain Mueller matrix solution is derived from vector radiative transfer, and is applied to numerical simulation of polarimetric radar pulse echoes from the stratified random media.The Mueller matrix solution contains seven scattering mechanisms of the stratified media: surface scattering from the rough interfaces, volumetric scattering from random stone scatterers (non-spherical scatterers are assumed), and their multi-interactions.As the radar pulse at L band is penetrating through the random surface, attenuation through the low loss regolith medium, polarimetric scattering through the stone scatter medium and rough surfaces are formulated in our Mueller matrix solution. Model parameters are set according to the study of the lunar regolith structure.Temporal characteristics and structure of the polarimetric echo profile are analyzed. It consists of a prominent peak due to the top boundary scattering and a complex tail due to the bottom boundary and stone volumetric scattering. Contributions of different scattering mechanisms, i.e. surface, volumetric scattering and interactions, are analyzed, and their dependence on model parameters such as the layer thickness and the content of FeO+TiO2, are also discussed. Simulation of pulse echoes might display a image of underneath structures. It reveals information of the depth and other properties of the lunar regolith layer, and demonstrates a potential new way to explore moon surface in future.
The imaging theory of rotary scanning synthetic aperture microwave radiometer is studied, and a new imaging algorithm based on pseudo-polar FFT is developed. The critical feature of the algorithm is that it involves only 1-D equispaced FFT and 1-D interpolation, so it is more fast and accurate for
application. In order to validate this new algorithm and analyze the antenna array effects on image reconstruction, the imaging of three typical designs of 8 elements antenna array is simulated by the pseudo-polar FFT method and linear interpolation based Cartesian FFT method. The results illustrate the superior performance of the new method and also indicate that the baseline' s uniformity and number have a great influence on the reconstruction, and the plane distributed antenna array is preferred rather than the linear distributed array for it has more baselines and good uniformity simultaneously.
Radar altimeter is one of the major payloads on microwave remote sensing. An altimeter will be embarked on the upcoming HY-2 satellite. In-orbit instabilities will occur in the radar system due to ageing effects, temperature floats, and space radiations and so on. Internal calibrations are applied to solve this problem. In this paper the authors describe the tasks of internal calibration and compare the two main calibration schemes, and choose the second for engineering design. Then the authors design the attenuation and delay parameters of the calibration channel. The authors also analyze the error sources occurring in calibration channels.
Microwave humidity sounder is one of the important payloads in FY-3 satellite. The microwave humidity sounder consists of the power unit, the data processor and control unit and the receiver. The data processor and control unit is the core of humidity sounder, functions of it are controlling system,
performing commands of FY-3, sampling data and transmitting data. It is very important that this unit is reliable and safe. According to the characteristics of the microwave humidity sounder, there are two parts in the data processor and control unit. One part is main, Another part is redundant. One of the two parts must be un-powered at anytime. We have compared three ways of redundancy, JFET-input operational amplifiers were used to be interface in finally. The characteristics of the amplifier are low consumption, high input impedance, output short-circuit protection and so on. In application of FY-3, the reliability of this redundancy scheme has been proven.
The microwave sctterometer on HY-II is a space-borne remote sensor designed by Center for Space Science and Applied Research, CAS. Its main application area is to measure the sea wind vector on the sea surface. This article will cover the design of digital signal processing system of microwave scatterometer and some experiments results.
Dual-channel Radiometers for Earth and Atmosphere Monitoring (DREAM) is main payloard of Korean science and technology satellite 2 (STSAT-2). The flying modes of DREAM have been developed and delivered to Korea. DREAM is a full power radiometer. When DREAM is in orbit, it will calibrate
with matched load and space radiation. DREAM antennas are small and do not scan because of restriction of the satellite. Receiver calibration method is adopted by DREAM. In the method, different antennas are used in calibration and measurement channel respectively and are connected with receiver by a TPST switch. System and acceptance test results show that DREAM meets Korean requirements of functions and performances. In the paper, STSAT 2 and the design of DREAM are introduced. DREAM main performances and system test results are presented.
The Imaging theory, retrieving algorithm and principle of thinned array of two dimensional synthetic aperture radiometer are presented, and based upon simulated annealing algorithm, two kinds of optimized thinned array are obtained. One is the array restricted in the circle area with rotating, and the other is the array restricted in T-strip area with the restriction that the antennas must be on the regular grids. Experimentation and simulation results proved that these kinds of thinned array are practical.
In order to monitor the ocean phenomena, such as ocean wave, ships, oil spill, internal wave and sea ice etc., the ocean monitoring satellite adopts a multi-polarization SAR with multi-mode. To identify the detail character of the object, the SAR utilizes its high resolution mode for fine imaging. To obtain the remote sensing information of the global ocean, the SAR utilizes its wide swath scan mode for fast covering. Based on the results of ERS and RADARSAT-1, the paper discussed the satellite orbit and the payload parameters with theoretical analysis and simulation.
As the civil and military demands for space-borne synthetic Aperture Radar developed, a higher- resolution, multi-polarized, multi-band and multi-mode SAR is required. This sparks the interest in the subject of broadband, dual-polarized phased array. A broadband dual-polarized antenna array for spaceborne SAR application is introduced. The array is formed with the active front-end, the RF distribution, and the necessary electronic components for power supply, control and operation. The basic active front end, named as active subarray module, comprises RF distribution networks and dual-polarized linear arrays each connected with a TR-module, with which a required array can be extended. The dual-polarized
microstrip antenna and waveguide slotted antenna array are designed as the radiating candidates of the active array. The dual-polarized stacked patch array, excited with coplanar microstrip for vertical polarization and aperture coupled microstrip for horizontal one, obtains a wide bandwidth, higher degree of isolation and good cross-polarization level. These owe to the stacked patch, corporate feeds, and elements excitation with equal amplitude but out phase method used. For the dual-polarized waveguide slotted antenna, a ridge waveguide longitudinal slotted array is used for vertical polarization and the non-inclined narrow wall slotted array for horizontal one. With the subarray, overload method, and novel waveguide
divider used, the waveguide slotted array achieves a broad bandwidth and compact cross section. The microstrip array and waveguide slotted array for X band applications are designed, fabricated and tested,showing a good performance. The comparison between two types of array indicates that the microstripantenna shows a broadband, low weight and low-cost performance while the slotted array is of low loss, high isolation and very low cross polarization but complex construct, heavy weight and expensive cost.
In this paper we propose a bistatic scattering model for electromagnetic scattering from a randomly rough surface, which is an extension to the advanced integral equation model. After lengthy mathematical manipulations, for the cross and the complementary incoherent powers, it is shown that each consists of two terms: one free from and the other related to the error function. The latter can be viewed as a correction term for previous calculations. The validity of this extended bistatic scattering model is demonstrated through the excellent agreements between model predictions and measurement data for statistically known surfaces.
A new method to measure ocean wave slope spectra using fully polarimetric Synthetic Aperture Radar (POLSAR) data was developed without the need for a complex hydrodynamic modulation transform function. There is no explicit use of a hydrodynamic modulation transfer function. The results estimated from NASA/JPL AIRSAR C-band polarimetric SAR data show that the ocean wavelength, wave direction and significant wave height are in agreement with buoy measurements. In the velocity bunching model, a nonlinear mapping relationship between dual-polarization SAR image spectra and ocean wave spectra is derived.
The alternative polarization mode of Envisat ASAR can offer two registered images with different polarization during one observation, so that more information can be gained from the two images. Ships detection capability can be improved by using the AP data. Therefore, in order to detect ships with Envisat AP data, the P-CFAR detector is introduced and adopted. Firstly, GIS data are adopted to mask the land areas in the AP data. Then the P-CFAR detector is applied to the AP data. By moving the slider window,the central cell' s information is calculated and compared with a threshold. Then all the candidate targets are detected. Finally, a compound discrimination algorithm comprised by several discriminators is performed to reduce the number of false alarms. To evaluate the capability of our algorithm, it is applied to some AP data, and results show that the P-CFAR algorithm can effectively detected the ship targets, even in a clutter condition.
The paper presents a novel approach for the airborne InSAR system imaging processing with motion compensation and automatic registration. Basing upon the feature of the dual-antenna radar data from the airborne InSAR system and using the high precise POS data, the novel approach can accomplish the position error compensation, interferometric phase error compensation and automatic registration of the InSAR image-pair directly at the imaging processing stage. The practical results indicate that the proposed approach is very suitable for the imaging process of a dual-antenna airborne InSAR system with its efficiency in improving the image quality and enhancing the image-pair coherence.
The dual-polarization ENVISAT ASAR Liaodong Bay 2005～2006 winter sea ice images in time sequence in were analyzed to study the ice detection capabilities of different polarization SAR images, and the results showed that the alternating polarization images were not suitable for ice classification due to their small backscattering dynamic ranges. Then the electromagnetic property response of different kinds of sea ice in Liaodong Bay were studied by using the SAR images and synchronous TM images. It was pointed out that SAR image could detect fast ice, level ice and deposited trash ice,but it was not reliable in detecting new ice, and the detecting result was affected by the growth phase of ice and its surrounding environment. And it also could not identify some types of ice like cake ice, due to the limitation of spatial resolution.
According to scaled real digital elevation maps (DEM) information, sets of single look complex(SLC) SAR images are simulated for interferometric missions, based on the SAR imaging mechanism and scattering model of two-scale rough surface. On the basis of the ant colony optimization (ACO), a novel phase unwrapping method is developed. This method is applied to the simulated sets of SAR images and real ENVISAT ASAR images of repeat-path orbits. As comparison with other conventional methods, this novel method shows advantages over existed phase unwrapping methods.
In this paper, we investigate a case-based reasoning (CBR) method for the classification of multi-temporal SAR images with the aid of ancillary information. Our scheme for the problem of multi-temporal SAR images classification comprises four main steps, including SAR image processing, construction of case library, case-based classification and post-classification processing. During the construction of case library, we employ a spatial-temporal analysis technique to remove fake cases, which can guarantee cases with high credibility. In the implementation of case-based classification, we propose a stratified similarity assessment and use it for the case-based matching. After that, we investigate an object-oriented post-classification method which takes the shape of land use region into account, as a result, it leads to a more meaningful classification, and the regenerate land use image or map can be easier compared and combined with usual GIS data. A series of multi-temporal SAR images for 2000 and
Windsat, the world' s first microwave polarimetric radiometer in space, was launched by U.S on January 6, 2003. It aims at testing the capability of polarimeteric radiometer remote sensing ocean surface wind vector from space. According to Windsat on-orbit brightness data, we built the ocean and atmosphere algorithm and retrived ocean wind vector, ocean surface temperature, water vapor and liquid water with physical statistical method and maximum likelihood estimation approach. Finally the retriveal results are compared with other global synchronous data. We made preliminary research on retriveing wind vector with microwave plarimetric radiometer.
Sea surface salinity (SSS) is crucial to understanding ocean dynamics and its role in the water cycle and climate system. Even though the window at L-band is the best choice for salinity remote sensing,the sensitivity of brightness temperature to SSS is lower than that of the other variables. This paper presents a review on the most accepted models existent in the literature that describe the emmissivity of the sea at L-band. Some of Models presented here are based on theoretical approaches and others are semi-empirical propositions.The results in the retrieved salinities with five different combination models used to retrieve salinities from the WISE data by Gabarro et al., which are Two-scale Method with Durden and Vesecky-spectrum, SSA scattering model with Elfouhaily wave spectrum, Hollinger' s and Camps' wind speed dependence model, and Gabarro' s wind speed and height dependence model, is summarized. Some of these models are used to retrieve salinity depending on the quality of the retrieved salinity the models will be evaluated.
The ground-based 12-channel radiometer has been observing for about one year (from August,2005 to August, 2006). The coefficient of the integrated water vapor between the radiometer and the radiosonde is above 0.97. The Temperature profile, the relative humidity profile and the water vapor profile can be obtained by the neural network algorithm. The three kinds of profiles are compared between the radiometer and the radiosonde. Although there are some difference between the radiometer and the radiosonde for the three kinds of profile, the profiles of the radiometer are valuable for its time continuity,un-attendant and less cost, and so on. There is a strong sand storm on April 17, 2006 in Beijing. The maximum integrated water vapor on that day is 2.25 cm, much larger than other day' s in April. The mean integrated water vapor is 1.057 cm in April. On the other hand, during that time, the temperature of the boundary layer, from the surface to the 1 km, went up. It means that the thermodynamic structure of the boundary layer will have some change, during the sand storm. All these atmospheric characteristics can beobserved by the ground-based 12-channel radiometer.
This paper presents a hybrid algorithm, combining analytic KA (Kirchhoff Approximation) and numerical CG (Conjugate Gradient), to compute the composite object and rough surface scattering. The MoM with CG method is used to first solve the EFIE of the object. Then the fields on rough surface are analytically expressed using KA method, and large memory and computations for those fields are greatly reduced. Iterative approach of surface fields induced on both the object and rough surface is utilized to take account interactions between the object and underlying rough surface. With Monte-Carlo method, bistatic scattering from a 2D PEC cylindrical object above PEC rough surface is well simulated by this hybrid algorithm. Multi scattering peaks are related to spatial orientation and geometry of the square column object.
AMSR-E brightness temperature data and MODIS land cover type data are combined to retrieval land surface temperature (LST). Using the MODIS data, we classified the global land surface into 16 types, and make assumption that in each land surface type, the emissivity of each channel is constant separately. Based on this assumption and the land surface types, we build land surface retrieval algorithms for each land surface types. Before the algorithms were built, we chose the pixels that with above 90%single land type area and pixels that the MODIS land surface temperature exceed 273 K. This is because the emissivity is dubious in snow cover, ice cover, and mixed-pixels. Coequally, considering the precipitation effect, we winkled the rainfall pixel from our dataset. Finally, we employed the algorithms to retrieval global land surface temperature of Jan to Oct, 2004. Compared with the MODIS land surface temperature product, the result is fine, with RMSE of 2～4 K.
Synthetic Aperture Radar(SAR) is a high resolution, modern side-look imaging radar. SAR images of ocean surface contain a wealth of information of mesoscale and sub-mesoscale marine atmospheric boundary layer (MABL) phenomenon. Thus it is a very important data source for MABL meteorology study. However this hot topic, which covers microwave remote sensing, meteorology and oceanology, etc. have got reported by few Chinese open literature. Based on such situation, firstly we summarize the recent MABL studies, and introduce the principle and methods of studying MABL with SAR images. As an example,ERS-2 SAR image covering Hong Kong region acquired on May 7, 2002 is used for the preliminary test of wind vector retrieval. The processing include:①pre-processing the SAR images, including Analog Digital Converter (ADC) compensation, accurate calibration and speckle removal; and②wind direction and wind speed retrieval with the classic SAR Wind Direction Algorithm spectral method. The wind direction thus estimated is however with 180°ambiguity. Buoy data collected by the Hong Kong Observatory are then used to resolve the uncertainty. Finally, the GMF(Geophysical Model Function)-CMOD4 is adopted to estimate the wind speed at the height of 10m above sea level.
Compared with the wind direction and wind speed data recorded by Hong Kong Observatory, the error of the retrieved wind directions of two selected regions, (20 km×20 km each) are 23.71°and 7.00°,respectively, while that of the retrieved mean wind speed are 0.18 m/s and -0.12 m/s, respectively. The results show that high quality wind vector can be acquired if strict pre-processing, classical spectral analysis algorithm and CMOD4 model are adopted. The results are very encouraging for the future MABL research.
More than 300 satellite images including SAR (ERS1/2, Radarsat and Envisat), SPOT, Landsat, IRS and NOAA AVHRR images from 1995 to 2005 were analyzed to obtain spatial and temporal distribution of internal waves in the South China Sea (SCS). The amplitude and speed are calculated based on the KdV equation and Levitus' historical mix-layer depth data. The statistical analysis showed that three areas including Luzon Strait, Dongsha Island and the Northeastern Hainan Island were found to have regular internal wave activity. Most of the internal waves travel westly. Near the Luzon Strait, the phase speed can reach 3 m/s, the amplitude can exceed 100 m; near the Dongsha Island, the phase speed is in1.5～2 m/s around, the amplitude is in 20～80 m around; in the western and northern part of Dongsha Island, the phase speed is in 1～1.5 m/s around, the amplitude is in 5～20 m around; in the northeastern of Hainan, the phase speed is in 0.4～0.8 m/s around, the amplitude is in 2～4 m around. The temporal distribution characteristics of internal waves are: the internal waves occur mostly from Apr. to Sept.,little internal waves are observed from Jun. to Mar. and Nov. to Dec.; in every month the internal waves have highly activities from 16 to 19th day.
Thunderstorms structure detection is a hot issue. Fine structure of the bottom of the thunderstorm has not yet been reported. An ERS-1 image was used to detect the bottom structure of a thunderstorm developed on 11 August 2002 in the Taiwan Strait. The meso-scale thunderstorm process is
discussed with simultaneous NCEP and NOAA AVHRR data. The results show that this process of thunderstorm is developed in the forefront of the front. The southerly and northerly wind shear provides the impetus for this process. The thunderstorm shows oval structure with semi-axis respectively 13km and10km. The heavy rains core in the center of the storm area reaches 5 km in diameter. The thunderstorm travels to the Northeast with a speed of 5.9m/s. There is a long organized caudate stripe in the rear of the thunderstorm. The thunderstorm structure diagnosis analysis suggested that this stripe is a foot mark from the tornado associated with the thunderstorm. It' s very interesting that there are atmospheric gravity waves trapped in the thunderstorm. The mechanism analysis supported that in the outflow region, the anti-cyclonic cold air falls down and encounters the cyclonic up warm air around. These two different streams leaded to the atmospheric wind shear and thus caused the wave generation. The wave contained at least 12 solitary waves, the wavelength were from 450 meters to 237.5 meters with an average value of 297.9 meters.
The effect of the phase noise of the local oscillator on the performance of millimeter-wave aperture synthesis radiometer is studied in this paper in terms of the correlation coefficient of two receiver signals. The phase noise of LO is modeled using a nonlinear equation, which describes the timming jitter effect of the LO. Simulations has been done for different error levels of the amplitude and angle of the correlation coefficients, in order to qualify the requirements on the LO phase noise level.
The error analyses on planar near-field measurement system of millimeter wave antenna are described. The effect of the position, shape and area of the truncation planar on the measured errors is proposed, and the error equation of the truncation error is deduced to provide a quantitative analysis.
Finally, the related computer simulations are carried out.
An experiment on the ground calibration of ChangE-1(CE-1) Microwave Radiometer based on the modified hardware radiative transfer model is introduced. The experimental results are analysed and validated, based on which analyzes the effect of temperature measurement on the results of ground calibration for microwave sounder. The temperature measurement with the accuracy of 0.5 K was tested and the test results indicated that the contribution of thermometric error to the accuracy of the receiver was less than 0.1 K, which means the temperature measurement met the requirements of the calibration. The calibration results have been modified remarkably by the correction of modified hardware radiative transfer model based on temperature measurement, when the working temperature of receiver is much different from that of ambient temperature.
FY-3 is the second generation polar orbit meteorological satellite serial of China. There is a radiometer-Microwave Radiometer Imager (MWRI) board on first satellite of FY-3 which will be launched in 2007 in first time. Xinjiang province as a test site was selected to develop the snow parameters algorithm for FY-3 MWRI in china area. Base on Chang' s semi-empirical model, AMSR-E brightness temperatures at 18.7 GHz,37 GHz and 89 GHz, four-month snow depth and SWE which are observed by meteorology station at Xinjiang in 2003 were used to establish regional algorithm. A monthly records of daily snow depth and SWE in JAN 2004 and AMSR-E SWE products were used to test the new algorithm. The surface water body, wet snow, precipitation and other anomalous scattering signals are screened using established methods. While compare estimated SWE by using new algorithm and SWE from AMSR-E with meteorological stations records respectively, the RMSE are 17.9 mm and 26.4 mm. The result show the new algorithm is better performance than algorithm for AMSR-E over Xinjiang province.
The receiving antenna effective temperature which is caused by the microwave noise sources of the inverse radiation are simulated in CST based on FIT (finite integration technique). According to the simplified model, the effect of the noise temperature, the calibration metal shield and the location of the receiving antenna are analyzed in detail.The calibration source of the microwave radiometer is mostly made by RAM (Radio Absorb Material)
with high RL (Return Loss). Under this condition, the received brightness temperature is composed of two parts. One is from calibration source which is reflected by metal shield, the other is from inverse radiation thermal noise which is penetrated antenna aperture and reflected by the calibration source then received by the antenna. The coherent addition on the inverse radiation thermal noise which is directly reflected by the receiving antenna and reflected by the calibration source is considered in this simplified model. However, the effective of the metal shield and the coupling between the shield and the antenna are considered moreover in FIT. According this simulation, about the 1K antenna temperature is attributed to the inverse radiation thermal noise temperature 400 K.
The echo data received in microwave remote sensor is always need to be Quadrature demodulated at intermediate frequency. Based on Nyquist sampling theory, the spectrum of LFM echo received by radar and the performance of digital filter are analysised in the Quadrature demodulation processing, the function of the Computational amount with Fs for received signal and the taps of quadrature sampling filter are educed. Aiming at a group of signals with different bandwidths, a series of filters corresponding to different Fs are designed, the performance and the computational amount are compared in order to get the optimal design.
Radiation pattern of sparse array antenna was applied to analyze the interference phenomenon occurred in the SAR imaging simulation of uniformly distributed point-targets, which were used to model a distributed target. In the bright area, both the signal-to-noise ratio and the definition of SAR image were very high, and the phase information was well preserved. However, in the dark area, both the amplitude and phase information were badly destroyed. The position and width of interference pattern were related to the observing angle, range resolution and carrier frequency. A simple method was used to remove the interference by assuming a random height distribution of each point target, so as to destroy the uniform distribution of point targets. Both the definition and resolution of SAR image were degraded after interference deleted, but they were still in accordance with the imaging effect of SAR system with corresponding resolution.
The micro-Doppler effect induced by mechanical vibrating or rotating of structures in a radar target will contaminate the body' s ISAR image. In the paper, the principle of micro-Doppler effect is introduced, and a method for extraction of the micro-Doppler information is presented, which can be used in ISAR imaging of targets with rotating parts, especially for those targets with some large rotating parts,such as helicopter. The spectrogram of micro-Doppler can be separated from the spectrogram of the target body based on the difference of their features, and then a clear ISAR image can be obtained. Meanwhile,some information of the rotating parts is achieved. Finally, a computer simulation is given to prove the effectiveness of the proposed method.
A novel approach for information retrieval and 3D-object reconstruction using multi-aspect high-resolution SAR imagery of urban area is briefly introduced. It includes CFAR edge detection of SAR images, automatic extraction of building images and Maximum-likelihood estimation of building
parameters. The fidelity of this approach is demonstrated by a building reconstruction experiment on a set of square-path Pi-SAR images.
A wavenumber form of double-peaked directional ocean wave spectrum is derived from the 6parameter double-peaked frequency spectrum and the cos-2s type spreading function. Then, using a simulation model based on the closed nonlinear integral transformation, the synthetic aperture radar(SAR) image cross spectra have been simulated from the double-peaked ocean wave spectra. The dependence of the simulated results on the SAR and ocean wave parameters is discussed. Besides, the results of SAR image cross spectra and SAR image spectra are compared.
Synthetic aperture radiometer imaging use sparse antennas array for reducing the cost. In this rocess , phase errors of the visibility function will sharply degrade the imaging quality. This paper resents a detailed analysis of system imperfections and a calibration modeling. Meanwhile, we introduce a real time alibration method-Redundant Spacing Calibration(RSC). And its simulation result proves that
this calibration method is very efficient under the two kinds of antenna arrays.
