China Remote Sensing
satellite ground station and its research and development
Wang Xinmin China Remote Sensing Satellite Ground Station P.O. Box 2434, Beijing, China Abstract The status, research and development of the China Remote Sensing Satellite Ground Station are described in the paper. Introduction It has been more three years since the operation of the China Remote Sensing Satellite Ground Station in December, 1986. Since then the Station has been running smoothly. It has acquired approximately 30,000 scenes of TM data, processed more than 2000 scenes, archived more than 2000 master films and provided a larger amount of TM data product to the remote sensing community. The station consists of two divisions: the operation division and the research and development division. The former is responsibility for receiving, processing, archiving and distribution of satellite data and renders services to the user's community, while the latter is to develop image processing system and technologies and to conduct signature and information content studies of the satellite data, pilot application studies for certain projects and also monitoring of natural disasters. General status of the operation division The operation division has three parts: receiving station, digital processing laboratory and photolab. The main responsibilities of the receiving station are acquisition and tracking of the satellite and receiving and recording of the satellite data onto HDDT. It is equipped with a 10 m. antenna and X/S land tracking and receiving equipment. It can cover approximately 855 of our Land territory and can receiving data from Landsat and SPOT. At present only Landsat TM data re received on routine basis. After adding some relevant demodulating equipment, it can be used for data reception from other remote sensing satellite, including Chinese satellite to be launched in 1994. The main functions of digital processing laboratory are ingesting HDDR data, decommutation and framing, PCD extraction processing, radiometric and geometric, generation of digital products and latent film transparencies. The main equipment consists of HDDR, frame synchronizer, processing subsystem with two VAX 11/780 And AP 180 V array processors and a stand alone film generation subsystem with VAX 11/750 and two B/W and color fire 240 film writers. Besides, there are four IIS terminals for QL, quality assessment and image analysis application the production capability is more than either 44 MSS scenes or 4 TM scenes per 12 hours. A cluster has been purchased to cluster 4 VAX 11/780 and VAX 11/750 together and a new VAX 6400 machine and array processors will be added to meet the processing requirements of other remote sensing satellite data. The photolab is equipped with all necessary B/W and color film and paper processors, photocolor composite and enlarging machines and all kinds of quality control and assurance instruments. The ordinary products are WRS framed after systematically corrected data. The radiometrically corrected with line shift alignment AA data and geodetically corrected PG data, etc., are produced under user's request. Functional upgrade in the past years In response to the practical needs and user's requests, the station did some functional upgrade:
It is a pipeline hardware oriented preprocessing system. In the first stage the system was jointly developed by our station and a American company. In 1987, due to problems of that company, we began to develop the system solely by our own effort. The system consists of: HDDT ingest, frame synchronizer, QL processing, 1A any 1B processing, CCT generation and image color display. A micro VAX 2 is used for system control and management, while the Motorola-68000 based hardwired blocks are responsible for various functional processing. 1B processing is performed by the micro VAX 2 with nearest neighbor resampling. The QL is carried out in real time at 9 seconds per frame. The annotated framed QL image is displayed on a 1k x 1k monitor. Look-up tables are used for 1A production at 2.5 min. per scene, while 1B product is generated at 10 min. per scene. While SPOT preprocessing system is functionally completed, it cannot be used as an operational system, due to lack of spare parts of hardwired functional modules. The same reason causes 1B processing performed on micro VAX 2 machine. Airborne multispectral data preprocessing system This is a fast real time system with front end and back processing subsystems. The former is a hardwire-oriented system, using hardwired functional blocks and multimicroprocessor parallel processing to perform high capacity optical disk playback, frame synchronizing, decommutation, radiometric and geometric tangent correction, CCT and floppy disk product generation. The latter is a micro VAX 2 based general image analysis system with 1k x 1k color display. A comprehensive set of remote sensing image processing software and airborne multispectral preprocessing software is integrated in the system. Pilot application study Based on information analysis and signature study of TM data, certain pilot application projects have been carried out to promote TM data application.
The station participated actively in the monitoring of the huge forest fire in Da Xin An Lin, North-East of China, evaluation of losses and studies of eco-environmental changes after the fire, (7) and also in the flood prevention and loss minimizing activities for the Yangtsu River, Yellow River and YongDing River in the past three years. These were highly praised and awarded by the Chinese Government. Monitoring of the off shore red storms, insect pests of the pine forest in the South and severe snow storm in Tibetin, last year were also carried out successfully. References
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