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Editor Work2014 Vol. 3, No. 3
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2014, 3(3): 249-255.
Abstract
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HJ-1-C is a SAR satellite owned by the Chinese Environment and Natural Disaster Monitoring constellation, and works together with the optical satellites HJ-1-A/B for monitoring environment and natural disasters. In this paper, the system design and characteristics of the first Chinese civil SAR satellite are described. In addition, the interface relation between SAR payload and platform is studied. Meanwhile, the data transmission capability, attitude, power, and temperature control that support SAR imaging are reviewed. Finally, the corresponding in-orbit verification results are presented.
HJ-1-C is a SAR satellite owned by the Chinese Environment and Natural Disaster Monitoring constellation, and works together with the optical satellites HJ-1-A/B for monitoring environment and natural disasters. In this paper, the system design and characteristics of the first Chinese civil SAR satellite are described. In addition, the interface relation between SAR payload and platform is studied. Meanwhile, the data transmission capability, attitude, power, and temperature control that support SAR imaging are reviewed. Finally, the corresponding in-orbit verification results are presented.
2014, 3(3): 256-265.
HJ-1-C is a Synthetic Aperture Radar (SAR) satellite in the Constellation of 2+1 for China environment and disaster monitoring. It works at S-band with a resolution of 5 m. SAR payload uses a reflector antenna and a high-power concentrated transmitter. Its light weight and high efficiency is very suitable for a small satellite platform. Now HJ-1-C satellite has been launched into orbit and has acquired Chinese first S-band SAR images from space, which demonstrate excellent quality and rich information about scenes imaged. This success verifies our design, testing and experiment work on the payload. With its following operation, HJ-1-C satellite is expected to make a great contribution to the applications of environment protection and disaster monitoring in China. This paper introduces the design and development of HJ-1-C SAR payload, present its main parameters and performance, describes its device details and its manufacture, testing and experiment process. Some images acquired in the orbit are showed.
HJ-1-C is a Synthetic Aperture Radar (SAR) satellite in the Constellation of 2+1 for China environment and disaster monitoring. It works at S-band with a resolution of 5 m. SAR payload uses a reflector antenna and a high-power concentrated transmitter. Its light weight and high efficiency is very suitable for a small satellite platform. Now HJ-1-C satellite has been launched into orbit and has acquired Chinese first S-band SAR images from space, which demonstrate excellent quality and rich information about scenes imaged. This success verifies our design, testing and experiment work on the payload. With its following operation, HJ-1-C satellite is expected to make a great contribution to the applications of environment protection and disaster monitoring in China. This paper introduces the design and development of HJ-1-C SAR payload, present its main parameters and performance, describes its device details and its manufacture, testing and experiment process. Some images acquired in the orbit are showed.
2014, 3(3): 266-273.
With truss deployable mesh parabolic reflector, the HJ-1-C SAR antenna has complex structure and multiple steps during the deployed processing. The design of the antenna is difficult in terms of deployed reliability and electrical performance. This paper makes intensive research on system, structure and electrical design, and the analysis of mechanical and thermal performance in the actual space conditions is also presented. The successful deploying in orbit and high image quality of the HJ-1-C satellite indicate that the mechanical, electronic, thermal and reliability design of the antenna satisfy the project requirement, and these research provides valuable experience for the design of the centralized mesh parabolic SAR antenna.
With truss deployable mesh parabolic reflector, the HJ-1-C SAR antenna has complex structure and multiple steps during the deployed processing. The design of the antenna is difficult in terms of deployed reliability and electrical performance. This paper makes intensive research on system, structure and electrical design, and the analysis of mechanical and thermal performance in the actual space conditions is also presented. The successful deploying in orbit and high image quality of the HJ-1-C satellite indicate that the mechanical, electronic, thermal and reliability design of the antenna satisfy the project requirement, and these research provides valuable experience for the design of the centralized mesh parabolic SAR antenna.
2014, 3(3): 274-281.
The system design of a S-band solid-state transmitter in satellite-borne SAR is introduced. A series of critical technologies, such as high reliability, environmental adaptability, and structure miniaturization, which are necessary in satellite applications, are analyzed and discussed. The technologies are experimentally verified at different periods. Multichannel combined technology is used for the transmitter, and the output peak power is more than 3 kW. Because of the high efficiency, small size, lightweight, and high power, it is especially applicable in small satellite platforms.
The system design of a S-band solid-state transmitter in satellite-borne SAR is introduced. A series of critical technologies, such as high reliability, environmental adaptability, and structure miniaturization, which are necessary in satellite applications, are analyzed and discussed. The technologies are experimentally verified at different periods. Multichannel combined technology is used for the transmitter, and the output peak power is more than 3 kW. Because of the high efficiency, small size, lightweight, and high power, it is especially applicable in small satellite platforms.
2014, 3(3): 282-287.
Expansion-driven HJ-1-C satellite components are prone to fatigue and fracture; thus, a reliability study on the optimal design is performed. According to the Failure Mode and Effects Analysis (FMEA) of the components, the main failure modes are stress relaxation and impact breakage of the torsion and scroll springs. On the basis of the failure modes, a prototype spring is tested, and the relative reliabilities are calculated. Then, reliability measures are proposed, and the design optimization of the springs is carried out. The improvements introduced by the prototype spring are indicative of the effectiveness and reliability of the design optimization process, which can help design and analyze similar antenna reflectors in the future.
Expansion-driven HJ-1-C satellite components are prone to fatigue and fracture; thus, a reliability study on the optimal design is performed. According to the Failure Mode and Effects Analysis (FMEA) of the components, the main failure modes are stress relaxation and impact breakage of the torsion and scroll springs. On the basis of the failure modes, a prototype spring is tested, and the relative reliabilities are calculated. Then, reliability measures are proposed, and the design optimization of the springs is carried out. The improvements introduced by the prototype spring are indicative of the effectiveness and reliability of the design optimization process, which can help design and analyze similar antenna reflectors in the future.
2014, 3(3): 288-294.
Based on the research and development efforts of satellite-borne lumped solid-state transmitters, the design of a satellite-borne high-power microwave amplifier module is introduced. Focusing on satellite-borne applications, aspects of the high-power density thermal design, multipactor proof design, EMC design and so on, which are critical technologies for a solid-state power amplifier, are discussed. Subsequently, experiments are used to verify the concept.
Based on the research and development efforts of satellite-borne lumped solid-state transmitters, the design of a satellite-borne high-power microwave amplifier module is introduced. Focusing on satellite-borne applications, aspects of the high-power density thermal design, multipactor proof design, EMC design and so on, which are critical technologies for a solid-state power amplifier, are discussed. Subsequently, experiments are used to verify the concept.
2014, 3(3): 295-300.
A novel serial feeding network with Defected Ground Structure (DGS) is proposed in this paper. The stripline feed network uses multilayer board laminated structure and DGS on the surface. The output amplitude can be decided by the dimension of the DGS. According to this characteristic, the dimension of the DGS can be modified to realize output amplitude with high precision.
A novel serial feeding network with Defected Ground Structure (DGS) is proposed in this paper. The stripline feed network uses multilayer board laminated structure and DGS on the surface. The output amplitude can be decided by the dimension of the DGS. According to this characteristic, the dimension of the DGS can be modified to realize output amplitude with high precision.
2014, 3(3): 301-306.
Solid-state transmitter with large power and high heat flux is a key equipment of an HJ-1-C satellite; therefore, it has a great influence on satellite thermal design. Thermal design ensures that the solid-state transmitter works well within the allowable temperature limits of the equipment. The solid-state transmitter thermal design and solved key problems are provided in accordance with the HJ-1-C characteristics. Moreover, an analysis of satellites on orbit was performed. Based on the telemetry data, the thermal control design is shown to satisfy the temperature requirements of the solid-state transmitter.
Solid-state transmitter with large power and high heat flux is a key equipment of an HJ-1-C satellite; therefore, it has a great influence on satellite thermal design. Thermal design ensures that the solid-state transmitter works well within the allowable temperature limits of the equipment. The solid-state transmitter thermal design and solved key problems are provided in accordance with the HJ-1-C characteristics. Moreover, an analysis of satellites on orbit was performed. Based on the telemetry data, the thermal control design is shown to satisfy the temperature requirements of the solid-state transmitter.
2014, 3(3): 307-313.
In this paper, the HJ-1-C SAR full-power radiation test design is presented. For the new problems caused by SAR high-power concentrated emissions, the radar-receiving channel-leakage power test is proposed to ensure the safety of the radar-receiving path, and the transceiver channel closed-loop radar system test is discussed. The experimental results show that the proposed HJ-1-C SAR full-power radiation test scheme is reasonable and feasible, with the desired outcome.
In this paper, the HJ-1-C SAR full-power radiation test design is presented. For the new problems caused by SAR high-power concentrated emissions, the radar-receiving channel-leakage power test is proposed to ensure the safety of the radar-receiving path, and the transceiver channel closed-loop radar system test is discussed. The experimental results show that the proposed HJ-1-C SAR full-power radiation test scheme is reasonable and feasible, with the desired outcome.
2014, 3(3): 314-319.
The HJ-1-C satellite is a Synthetic Aperture Radar (SAR) satellite of a small constellation for environmental and disaster monitoring. At present, it is in orbit and working well. The SAR system uses a mesh reflector antenna and centralized power amplifier, and has an internal calibration function in orbit. This study introduces the internal calibration modes and signal paths. The design and realization of the internal calibrator are discussed in detail. Finally, the internal calibration data acquired in orbit are also analyzed.
The HJ-1-C satellite is a Synthetic Aperture Radar (SAR) satellite of a small constellation for environmental and disaster monitoring. At present, it is in orbit and working well. The SAR system uses a mesh reflector antenna and centralized power amplifier, and has an internal calibration function in orbit. This study introduces the internal calibration modes and signal paths. The design and realization of the internal calibrator are discussed in detail. Finally, the internal calibration data acquired in orbit are also analyzed.
2014, 3(3): 320-325.
Synthetic Aperture Radar (SAR) is a coherent imaging radar. Hence, coherence is critical in SAR imaging. In a coherent system, several sources can degrade performance. Based on the HJ-1-C SAR system implementation and sensor characteristics, this study evaluates the effect of frequency stability and pulse-to-pulse timing jitter on the SAR coherent performance. A stable crystal oscillator with short-term stability of 101.010 / 5 msis used to generate the reference frequency by using a direct multiplier and divider. Azimuth ISLR degradation owing to the crystal oscillator phase noise is negligible. The standard deviation of the pulse-to-pulse timing jitter of HJ-1-C SAR is lower than 2ns (rms) and the azimuth random phase error in the synthetic aperture time slightly degrades the side lobe of the azimuth impulse response. The mathematical expressions and simulation results are presented and suggest that the coherent performance of the HJ-1-C SAR system meets the requirements of synthetic aperture radar imaging.
Synthetic Aperture Radar (SAR) is a coherent imaging radar. Hence, coherence is critical in SAR imaging. In a coherent system, several sources can degrade performance. Based on the HJ-1-C SAR system implementation and sensor characteristics, this study evaluates the effect of frequency stability and pulse-to-pulse timing jitter on the SAR coherent performance. A stable crystal oscillator with short-term stability of 101.010 / 5 msis used to generate the reference frequency by using a direct multiplier and divider. Azimuth ISLR degradation owing to the crystal oscillator phase noise is negligible. The standard deviation of the pulse-to-pulse timing jitter of HJ-1-C SAR is lower than 2ns (rms) and the azimuth random phase error in the synthetic aperture time slightly degrades the side lobe of the azimuth impulse response. The mathematical expressions and simulation results are presented and suggest that the coherent performance of the HJ-1-C SAR system meets the requirements of synthetic aperture radar imaging.
2014, 3(3): 326-331.
Conventional software frame synchronization methods are inefficient in processing huge continuous data without synchronization words. To improve the processing speed, a real-time synchronization algorithm is proposed based on reverse searching. Satellite data are grouped and searched in the reverse direction to avoid searching for synchronization words in huge continuous invalid data; thus, the frame synchronization speed is improved enormously. The fastest processing speed is up to 15445.9 Mbps when HJ-1C data are tested. This method is presently applied to the HJ-1C quick-look system in remote sensing satellite ground stations.
Conventional software frame synchronization methods are inefficient in processing huge continuous data without synchronization words. To improve the processing speed, a real-time synchronization algorithm is proposed based on reverse searching. Satellite data are grouped and searched in the reverse direction to avoid searching for synchronization words in huge continuous invalid data; thus, the frame synchronization speed is improved enormously. The fastest processing speed is up to 15445.9 Mbps when HJ-1C data are tested. This method is presently applied to the HJ-1C quick-look system in remote sensing satellite ground stations.
2014, 3(3): 332-338.
This study is concerned with the design and implementation of a real-time processing system of full resolution quick-look image of HJ-1 environmental satellite C SAR based on high-performance clusters. The system processes the first quick-look SAR image on December 9, 2012. The results show that the design and implementation of the quick-look processing system satisfies the real-time SAR image processing performance requirements at full resolution. Moreover, this system is the first real-time business system of full-resolution quick-look spaceborne SAR images in China.
This study is concerned with the design and implementation of a real-time processing system of full resolution quick-look image of HJ-1 environmental satellite C SAR based on high-performance clusters. The system processes the first quick-look SAR image on December 9, 2012. The results show that the design and implementation of the quick-look processing system satisfies the real-time SAR image processing performance requirements at full resolution. Moreover, this system is the first real-time business system of full-resolution quick-look spaceborne SAR images in China.
2014, 3(3): 339-351.
The HJ-1C satellite was successfully launched in November 19, 2012. The HJ-1C and HJ-1A/1B satellites, which were launched in September 06, 2008, constitute the 2+1 small satellite constellation for environmental and disaster monitoring. This study focuses on the analysis and evaluation of the satellite
performance with respect to environmental remote sensing, including land use interpretation, land cover classification, oil spill identification, retrieval of sea waves, and monitoring of coastal mariculture. The data used in this study cover the city of Beijing and the sea of the Fujian Province. Nine HJ-1C satellite images (level-2, S band, VV Pol, strip mode, 5 m resolution) from December 2012 to January 2013 are used. The conclusions are as follows: (1) the HJ-1C SAR images can be used to manually identify farmland, woodland, roads, rivers, urban construction, and rural residential areas; (2) the accuracy of the automatic land cover classification increased significantly when the HJ-1C SAR and HJ-1B CCD fusion images are used; (3) the HJ-1C satellite can be used to identify oil spills, to invert wave parameters, and to extract information regarding inshore aquaculture.
The HJ-1C satellite was successfully launched in November 19, 2012. The HJ-1C and HJ-1A/1B satellites, which were launched in September 06, 2008, constitute the 2+1 small satellite constellation for environmental and disaster monitoring. This study focuses on the analysis and evaluation of the satellite
performance with respect to environmental remote sensing, including land use interpretation, land cover classification, oil spill identification, retrieval of sea waves, and monitoring of coastal mariculture. The data used in this study cover the city of Beijing and the sea of the Fujian Province. Nine HJ-1C satellite images (level-2, S band, VV Pol, strip mode, 5 m resolution) from December 2012 to January 2013 are used. The conclusions are as follows: (1) the HJ-1C SAR images can be used to manually identify farmland, woodland, roads, rivers, urban construction, and rural residential areas; (2) the accuracy of the automatic land cover classification increased significantly when the HJ-1C SAR and HJ-1B CCD fusion images are used; (3) the HJ-1C satellite can be used to identify oil spills, to invert wave parameters, and to extract information regarding inshore aquaculture.
2014, 3(3): 352-360.
Road network extraction in SAR images is one of the key tasks of military and civilian technologies. To solve the issues of road extraction of HJ-1-C SAR images, a road extraction algorithm is proposed based on the integration of ratio and directional information. Due to the characteristic narrow dynamic range and low signal to noise ratio of HJ-1-C SAR images, a nonlinear quantization and an image filtering method based on a multi-scale autoregressive model are proposed here. A road extraction algorithm based on information fusion, which considers ratio and direction information, is also proposed. By processing Radon transformation, main road directions can be extracted. Cross interferences can be suppressed, and the road continuity can then be improved by the main direction alignment and secondary road extraction. The HJ-1-C SAR image acquired in Wuhan, China was used to evaluate the proposed method. The experimental results show good performance with correctness (80.5%) and quality (70.1%) when applied to a SAR image with complex content.
Road network extraction in SAR images is one of the key tasks of military and civilian technologies. To solve the issues of road extraction of HJ-1-C SAR images, a road extraction algorithm is proposed based on the integration of ratio and directional information. Due to the characteristic narrow dynamic range and low signal to noise ratio of HJ-1-C SAR images, a nonlinear quantization and an image filtering method based on a multi-scale autoregressive model are proposed here. A road extraction algorithm based on information fusion, which considers ratio and direction information, is also proposed. By processing Radon transformation, main road directions can be extracted. Cross interferences can be suppressed, and the road continuity can then be improved by the main direction alignment and secondary road extraction. The HJ-1-C SAR image acquired in Wuhan, China was used to evaluate the proposed method. The experimental results show good performance with correctness (80.5%) and quality (70.1%) when applied to a SAR image with complex content.
2014, 3(3): 361-367.
HJ-1C satellite was the first synthetic aperture radar satellite for civil use in China, it had the strip and scan mode. According to the characteristics of ScanSAR of HJ-1C satellite, a geo-correct algorithm based on equivalent RD model was given in this paper on the base of ECS image processing algorithm and traditional Range-Doppler location method. First azimuth mosaic was presented by time serial relationship, then the different burst was stitched by range, the equivalent parameters were fitted to location on RD model. At last the ScanSAR image was geo-corrected. The HJ-1C satellite data results showed that the location accuracy of ScanSAR of HJ-1C satellite less than 100 m and the geo-correct algorithm was realized in 10 s under 24 cores parallel.
HJ-1C satellite was the first synthetic aperture radar satellite for civil use in China, it had the strip and scan mode. According to the characteristics of ScanSAR of HJ-1C satellite, a geo-correct algorithm based on equivalent RD model was given in this paper on the base of ECS image processing algorithm and traditional Range-Doppler location method. First azimuth mosaic was presented by time serial relationship, then the different burst was stitched by range, the equivalent parameters were fitted to location on RD model. At last the ScanSAR image was geo-corrected. The HJ-1C satellite data results showed that the location accuracy of ScanSAR of HJ-1C satellite less than 100 m and the geo-correct algorithm was realized in 10 s under 24 cores parallel.
2014, 3(3): 368-374.
On November 19, 2012, HJ-1-C was launched successfully, which is the first civil Synthetic Aperture Radar (SAR) satellite in China and is also the only S-band SAR on-orbit satellite in the world. During the on-orbit period, National Disaster Reduction Center of China (NDRCC) preliminarily evaluated the application capacity towards the ice disaster, and also evaluated the relative precision by using multispectral images of ZY-3 satellite. The result shows that, the S-band SAR satellite has super response towards ice. Entirely freeze-up area, non entirely freeze-up area and drift ice area can be effectively identified, and the S-band SAR satellite has better disaster reduction application capacity. The S-band SAR satellite data will fill up the bands blank of SAR satellite in China and even the world, and its disaster reduction potentiality remains to be excavated further more.
On November 19, 2012, HJ-1-C was launched successfully, which is the first civil Synthetic Aperture Radar (SAR) satellite in China and is also the only S-band SAR on-orbit satellite in the world. During the on-orbit period, National Disaster Reduction Center of China (NDRCC) preliminarily evaluated the application capacity towards the ice disaster, and also evaluated the relative precision by using multispectral images of ZY-3 satellite. The result shows that, the S-band SAR satellite has super response towards ice. Entirely freeze-up area, non entirely freeze-up area and drift ice area can be effectively identified, and the S-band SAR satellite has better disaster reduction application capacity. The S-band SAR satellite data will fill up the bands blank of SAR satellite in China and even the world, and its disaster reduction potentiality remains to be excavated further more.
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