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This study examines the imaging problems in airborne synthetic aperture ladar with single detector and dual detectors along tracks under platform vibration condition. Because platform vibrations affect imaging processing for short intervals negligibly, a method uniting the subaperture imaging and phase gradient autofocus is considered for single-detector ladar. To obtain long stripmap images in azimuth, the stripmap phase gradient autofocus method and the subaperture image mosaic process using Doppler centroid estimation are used. Their performance is analyzed and compared. Considering the shortage of single-detector ladar, a method based on along-track dual-detector interferometric processing is proposed to estimate and compensate for the vibration phase error. The simulation verifies the effectiveness of the proposed methods.

In this study, the performance of three phase-modulated signals used in airborne Synthetic Aperture Ladar (SAL) is investigated. The transmitting and receiving modes and imaging processing methods for these signals are studied. Considering that the swath of the airborne SAL is very narrow, in order to reduce the AD sampling rate of the wideband signal, a “phase-dechirping” receiving mode is proposed for the phase-modulated signal based on the Linear Frequency Modulation (LFM) signal. The imaging simulation results for these three phase-modulated signals validate the effectiveness of the proposed method.

In this study, the concept and system of a distributed POS are discussed. Based on the different operation modes, the principle technical parameters and requirements for optical camera and imaging radar with multiple subarray antennas are presented. Further, technical approaches to obtain precise position and attitude information for the POS are investigated, and some possible applications are proposed.

The current status and the domestic research problems of air-borne Synthetic Aperture Ladar (SAL) are introduced and key technologies are analyzed. Based on a principle prototype, the system implementation scheme with a combination of SAR electronics technology and optical technology is given. The future practical system metrics and technological approaches are analyzed. Besides, application direction of Synthetic Aperture Ladar is clarified.

In this paper, modeling of the channel leakage error of a three-baseline MMWInSAR (MilliMeter Wave Interferometric Synthetic Aperture Radar) is analyzed, and the mathematical expression of the error’s parameters and interference phase error is deduced. Furthermore, using quantitative analysis, the paper investigates the impact on the interferometric phase error and elevation error from the channel leakage. Finally, a compensation method for the channel leakage error is presented. The results of simulation experiments verified the effectiveness of the compensation method.

Major and REE geochemistry and multi-fractal analysis of two types of bauxite (primary bauxite and accumulated bauxite) ores were studied in Pingguo bauxite orefield in western Guangxi, China. The results of geochemical data show that the accumulated bauxite has a feature of high AlO whereas relative low FeO and SiO contents compared to the primary bauxite. The similar chondrite-normalized rare earth element (REE) patterns illustrate that they have a cognate relationship. However, the negative Ce anomalies of primary bauxite and positive Ce anomalies of accumulated bauxite indicate that the ore-forming system changed from reducing environment to oxidation environment. The results of multi-fractal spectrum and parameters of AlO, FeO and SiO between primary bauxite and accumulated bauxite show that the distinct multi-fractal spectrum parameters reflect the different grade distribution between accumulated and primary bauxite ores. Metallogenic process from primary bauxite to accumulated bauxite is accompanied by the loss of diffluent elements (e.g., Si and S) and enrichment of stable elements (e.g., Al and Fe) in the surface environment. Among the rest, the migration mechanism of iron during the evolutionary process from primary ore to accumulated ore can be described as combined leaching and chemical weathering action with participation of sulfur. [ABSTRACT FROM AUTHOR]

Based on dual-frequencies dual-apertures spaceborne SAR (Synthetic Aperture Radar), a new SAR system with four receiving channels and two operation modes is presented in this paper. SAR imaging and Moving Target Indication (MTI) are studied in this system. High resolution imaging with wide swath is implemented by the Mode I, and MTI is completed by the Mode II. High azimuth resolution is achieved by the Displaced Phase Center (DPC) multibeam technique. And the Coherent Accumulation (CA) method, which combines dual channels data of different carrier frequency, is used to enhance the range resolution. For the data of different carrier frequency, the two aperture interferometric processing is executed to implement clutter cancellation, respectively. And the couple of clutter suppressed data are employed to implement Dual Carrier Frequency Conjugate Processing (DCFCP), then both slow and fast moving targets detection can be completed, followed by moving target imaging. The simulation results show the validity of the signal processing method of this new SAR system. [ABSTRACT FROM AUTHOR]