In this paper, the principle of synthetic aperture microwave radiometer (SARad) is introduced. The differences between SARad for earth observation and its parentage in radio astronomy, the synthetic aperture radio telescope, are analyzed, which results in two key technologies of SARad: the design of baseline combination and the image retrieval algorithm. In this paper, the general relationship between the output of an interfe rometer, which is called the visibility function or the spatial frequency sampling, and the baseline parameters is presented. The general formulation of visibility function and functional expression of the brightness temperature distribution from retrieved from visibility function are derived. Some discussions on the image retrieval and numerical simulations are given.
A study on the influence of the imbalance of amplitude and phase of I/Q on the pulse compression and
the way to correct it has been performed. Study shows that the imbalance of amplitude and phase will make the
side lobe higher and the width of main lob wider. When the imbalance of amplitude is in the range of±15%,
and the phase imbalance is in the range of±3°, the influence can be neglected. When imbalance of amplitude is
beyond the range of±25%, and the phase imbalance is beyond the range of±10°, however, the influence is
serious and the correction must be done. The method of correction proposed in this paper is to consider the
corrected I/Q into the reference function and then, perform the matching filtering on the signal. Simulation
results show that the effect of correction is very good. By doing so, we can reduce the requirement on the
hardware design of I/Q demodulator.
Under the support of the 863-2 space project, W-band and F-band millimeter microwave has been
developing in our laboratory since 1998. It is the first time to study W and F band microwave radiometers in our
country. F-band microwave radiometer is being developed now, and the system integration of W-band
microwave radiometer has been finished. The system characteristics has been tested and will be introduced in
detail in this paper.
The principle of ocean Return Signal Simulator (RSS) is briefly introduced, and a design of full system RSS is presented. The multitone digital synthesizer is employed to simulate the spectra of ocean return signal. The pulse regenerative technique is adopted to precisely and accurately simulate the two way path delay of the altimeter transmitting signal and its point target signal. The synchronizing modulation technique is adopted to implement the modulation of the simulated ocean return to the altimeter point target signal, to realize the simulation of the full system ocean return.
The elements impacting on measurement accuracy of microwave radiometer are analyzed in the angle
of error measurement theory, and four temperature concepts that development and application of microwave
radiometer bases on are presented, and some detailed technique schemes on measurement accuracy improvement of groundbased, airborned and spaceborned microwave radiometer in the view of application conditions.
In this paper, prototype of a two-channel L-band interferometric synthetic aperture microwave
radiometer, which is infect a two-element microwave interferometer, is designed and developed. The
correlation experiment is conducted. Results of the experiment show that phase difference can be exactly
retrieved with the complex correlator, which can be a core component of a synthetic aperture radiometer.
In the design of Digital Ground-based Radar Scatterometer, Digital Signal Processing(DSP) is used to
do IF searching, IF estimation, adaptive band-pass filtering, detecting, etc and achieve high measuring speed
and accuracy. Four-band scatterometer,which includes S-Band, C-Band, X-Band and Kuband is realized with
this method. The system structure, algorithm and the experiment results are introduced in this paper.
Radar altimeter(RA) is a kind of active microwave remote sensor,which can measure the distance
between the platform and the sea surface,the ocean wave height and the back scattering coefficient.The control
system performs an important action in RA,which tracks the return wave and gives the measurement results in
real time.
In this paper,the characteristic of ocean echo is analyzed according to the ocean echo Model of Brown.
Either the ocean returen wave noise with an exponential distribution,or the thermal noise with a uniform
distribtuion are simulated to discover the statistics characteristic of the return wave form.A new space borne
radar altimeter tracker based on maximum likelihood estimate (MLE) is completed,which includes height loop,
SWH loop and AGC loop.The perfect haleness and accuracy of the tracker is shown in the flight experiment.
The principle,the hardware design and the work specifications of the tracker are present together with some
flight experiment data.
The digital auto-gain compensative microwave radiometer is a new type of microwave radiometer. The
ystem gain fluctuation and effective system noise fluctuation can be efficiently eliminated using the detectable
ariation when the standard signal pass through the system , and the long term stability is optimal. This paper
uilt the computer simulative model of the digital auto-gain compensative microwave radiometer according to the
roperty of the target' s microwave radiant energy passing through the system, and the combination method of
athematics and physics is used . In this paper the simulative analytical results correspond with the analytical
esults in theory and operating results of actual radiometer system. Also, some main problems when we
eveloped the multi-frequency space borne microwave radiometer can be explained.
It has been proven that there exists heat radiation from any object whose temperature is greater than
absolute zero by therories and studies.Brightness temperature is usually adopted to describe this radiation
characteristic,which varies with the geometry and dielectric characteristics of targets.Microwave radiometer is a
category of instrument,which is applied to measure the heat radiation characteristic of one target and very useful
in observing the earth from satellite.In fact,it is one receiver with high sensitivity since the radiation signal is
extremely weak,even weaker than the receiver background noise.This receiver consists of antenna,broad
bandwidth receiver,and data recorder.
Studies in the past have shown that the collected data are of very confusion if microwave radiometers are
not calibrated and validated before application, so microwave radiometer calibration techniques are very
important.Microwave radiometers can be utilized on ground-based,airborne and satellite-borne platforms,and
there are different demands and difficulties about microwave radiometer calibration accordingly,so it is necessary
to discuss the calibration on different platforms.In this paper,the calibration techniques of ground-based,
airborne and satellite-borne microwave radiometers are discussed,and some problems are also mentioned.
The recent developing status both in china and abroad on synthetic aperture radar is reviewed in the
er. The trends of synthetic aperture radar in the early of coming century are analyzed, that include: multi-
ameter (multi-frequency, multi-polarization, multi-angle, etc.) synthetic aperture radar; interferometric
synthetic aperture radar; spotlight SAR; interference and anti-interference of SAR; SAR constellation and
technology of calibration.
Based on multiple high techniques,the airborne digital camera,develeped in 1990' s,has advantages of
conventional photogrammetirc carmera.It has shown great potentialites in various application fields of remote
sensing.After introducing its international developing status as a focus,the auther gave some comments on some
problems such as spatial resolution,operational efficienty, techniques of acquisition and storage,the quality of
images,the influence of moving platform,spectral response and stereo imaging,etc.It is predicted that the
airborne digital carmera will become one of the most potentical means of airborne remote sensing during 21st
century.
With the exploitation of marine oil resources,the oil-spilling accidents on oil platform occur more
frequently than ever.It' s very important for spilling-oil reclamation and hazard loss assessment to trace and
monitor spilling-oil dynamically and properly.Through the analysis of LANDSAT TM image of oil-spilling
accidents in the platform outside Huanghekou in the end of 1996,this paper has shown the spectra responding of
oil film belt of different bands.It also dedicates that the spatial resolution of TM is very helpful to discriminate
the distribution of oil film belt in beaches and ditches.In 1~4 bands of TM the spectral featrue is very distinct.
It' s a pity that in the detection of spilling oil accidents images of oil-spilling zones are usually not available for the
influence of clouds.
During selecting the routes, the application of RS and GIS is very significant to reduce the cost of
project and forecast the future hidden trouble. In the case study of Guanling——Xingren highway in the Karst
mountain area, the authors apply RS and GIS to evaluate the geological condition and feasibility of the project.
The result confirms that the design of highway is feasible. The study indicates that we should pay attention to
the enriched-water fault that is the greatest hidden trouble during the construction of highway in the Karst
mountain area.
