Jingshan Jiang

Design of the second generation microwave humidity sounder (MWHS-II) for Chinese meteorological satellite FY-3

Design and Technical specification parameters of MWHS-II (MicroWaves Humidity Sounder) of FY-3 satellite are presented, which include much improvements compared to MWHS onboard FY-3A/B satellite launched in 2008 and 2010. Especially MWHS-II adds 8 channels at 118.75GHz to sound temperature information for the first time internationally. The simulation results show that MWHS-II will play an important role in the meteorological sounding system for measuring global atmospheric temperature and water vapour profiles.

HY-2A radar altimeter design and in flight preliminary results

HY-2A, the Chinas first satellite for oceanic dynamic environment measurement, was launched on August 16th, 2011. As one of main payloads of HY-2A, HY-2A radar altimeter (RA/HY-2A) has been operating stably since the launch, and obtained a lot of scientific data. RA/HY-2A is a dual-frequency (Ku and C band) radar altimeter with a conventional pulse-limited method, and some new techniques such as model compatible tracker are adopted in it. The accuracy of RA/HY-2A is better than 2cm (@4m SWH) or 4cm (@20m SWH), and the inversion results show that RA/HY-2A meets the design requirements. In this paper, the design and in flight results of RA/HY-2A are discussed.

Research Activity on Synthetic Aperture Radiometry in CSSAR/CAS

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 progress of this technology have been achieved in both one dimensional and two dimensional cases since 1990’s. The typical instruments are ESTAR and MIRAS, developed by NASA (and umass) and ESA respectively. Relative research has also been conducted in China, mainly by National Microwave Remote Sensing Laboratory (NMRS Lab), Center for Space Science and Applied Research (CSSAR), Chinese Academy of Sciences (CAS), since the middle of 1990’s. A C-band and an X-band instrument has been developed. In this paper, research activities on synthetic aperture radiometry in CSSAR/CAS will be reviewed and summarized, including the development of the instruments. Finally, further plans in synthetic aperture radiometry in CSSAR/CAS will also be prospected.

A Ku-band rotating fan-beam scatterometer: Design and performance simulations

This paper introduces the design and simulation results of a Ku-band rotating fan-beam radar scatterometer for ocean surface wind vector measurement. It will be flown on a small satellite dedicated to provide data for investigation of the ocean wave and ocean surface wind vector interactions, along with another payload for measurement of directional ocean wave spectra by a real-aperture radar with multiple scanned pencil beams. Key issues about the design of a Ku-band rotating fan-beam radar scatterometer, and results of performance simulations are provided as well. The performance of the system is simulated by the absolute and relative specifications. For the absolute specifications, retrieval performances for both wind speed and wind direction are evaluated, with the maximum likelihood method being employed. For the relative specifications, the figures of merit (FOM) is simulated, for comparison with other Ku-band scatterometers and optimization of system parameters. Simulation results of both the σ° precision and wind retrieval accuracies for different wind speed from 4m/s to 24m/s will be provided, which shows that SCAT can satisfy the performance requirements within most part of the swath.

In-orbit performance of Microwave Humidity Sounder (MWHS) of the Chinese FY-3 meteorological satellite

FY-3A (Feng Yun means wind and cloud in Chinese) meteorological satellite of China was successfully launched on May 27, 2008. MWHS (MicroWave Humidity Sounder) is a very important payload for measuring global atmospheric water vapour profiles. In this paper, the authors will describe the system configuration and parameters of MWHS. Moreover it gives the testing results in-orbit and comparing with AMSU-B which has been installed on NOAA-17.

Moving target imaging by both Ka-band and Ku-band high-resolution radars

The experimental work on testing the wide-band transmitters and receivers developed for Ka-band and Ku-band radar systems, as well as the signal processing algorithms were introduced. A city light-railway train was selected as the imaged target. The wide-band transmitters and receivers were designed based on the stepped-frequency chirp signal (SFCS) with 2GHz bandwidth synthesized. The Super-SVA technique was used to deal with the case of transmitting SFCS with band gaps between subchirps for purpose of achieving the same bandwidth using as less as possible subpulses. Both Ka-band and Ku-band high-resolution radar images were obtained, which show that Ka-band images are much clear than that of Ku-band as we expect. There are two reasons to explaining this, one reason is due to the electromagnetic scattering of train itself are different for Ka-band and Ku-band frequencies, and the other reason is due to the interactions, i.e. multi-reflection or multi-scattering between the train and the side metal fences or the lamp post are different.

An interferometric imaging altimeter applied for both ocean and land observation

This paper introduces an interferometric imaging altimeter system designed for both ocean and land observations. This sensor combines the functions of interferometric radar altimeter and SAR together and is aimed to provide centimeter- level accuracy of topography for ocean and meter-level accuracy of topography for land. With the interferometry technique, a wide swath of 80 km is achieved, and with the synthetic aperture technique, a resolution of 100 m for land observation is achieved. System design is outlined and some preliminary results are presented.

A new tracker for ocean-land compatible radar altimeter

Satellite radar altimeter is an active microwave remote sensor for obtaining ocean topography, as well as the marine and land ice mass fluxes at a global scale. Because the echo properties of ocean, land and pole ice are very different, the on-board tracker of radar altimeter should have the ability to handle the distinct signals automatically. In this paper, a new tracker for ocean land compatible, the model compatible tracker (MCT), is proposed. In MCT, two track algorithms, MLE (Maximum likelihood Estimate) and OCOG (off center of gravity), cooperate in parallel. Therefore, not only the good accuracy but also the robustness can be realized in real time on board. So MCT is very suitable for the ocean-land compatible radar altimeter. The principle of MCT, the cooperation strategy for the two algorithms, the adaptive bandwidth technique, and the realization of MCT are discussed in this paper.

Conical beam interferometer: FPIR concept and development

This paper presents a novel concept of one dimensional full polarization interferometric radiometer (FPIR). Purpose of FPIR is to implement high resolution polarimetric radiome-try without large antenna and complex electricity. The operation principle of FPIR is introduced. Advantages of the polarimetric measurement of FPIR are achieved by squint antenna beam, interlaced dual polarized array, unique polarization switching and shared receivers. An example of the interlaced array and the particular switching sequence is discussed. The development of FPIR demonstrator is presented. Element waveguide antenna of the demonstrator is measured within a ground plane. A breadboard receiver has been built. A special digital correlator, which is compatible with both the analog and digital demodulation, is designed.

Calibration and error analysis of a Ka-band fully polarimetric radiometer built with wideband microstrip correlator

In this paper we present calibration and error analysis of our Ka-band fully polarimetric radiometer, the radiometer used a wideband microstrip correlator. The calibration method is based on the tri-polarimetric calibration technique of Gasiewski and Kunkee, but is extended to provide the calibration of the fourth Stokes parameter using a retarder plate. A method to determine the phase shift of the retarder plate is introduced, a calibration matrix inversion technique is described as well. The calibration uncertainties and calibration error analysis are discussed at last.