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With the rapid development of the GNSS receiver's performance, almost all the commercial receivers have the ability of hot start. The main algorithm of fast positioning is how to get the position before frame synchronization when hot start. Because of the incomplete information of the pseudorange calculation before frame synchronization, the pseudorange is calculated by its estimation of integer millisecond...
As with the development of satellite communication, high speed downlink transmission is an important factor communication systems in the near future. In considering of this demand, we propose an Orthogonal Frequency Division Multiplexing (OFDM) based transmission strategy for mobile satellite communication. Based on conventional territory wireless communication technology, we explore OFDM frame structure...
Radar signal sorting, which de-interleaves pulse sequences from different radar emitters, is one of the key techniques in Electronic Support Measures (ESM) system of modern warfare. As the electromagnetic environment in modern electronic wars is complex and dense, conventional multi-parameter de-interleaving techniques cannot achieve satisfactory accuracy. Although clustering algorithms have shown...
A novel image encryption system based on the iterative fractional Fourier transform and the pixel scrambling technique is presented. During the procedure of image encryption, the ciphertext is randomly generated and the original image has been interpolated and divided into several equal sub-images. Via constructed the relationship between the ciphertext and the sub-images, a large number of phase...
This paper mainly investigates the bispectrum property of sea clutter. For non-Gaussian sea clutter, bispectrum can reveal its property from higher-order probability structures, which is complementary to current second-order theory based research. Bispectrum estimation of sea clutter is accomplished by using the FFT-based method with a frequency-domain Rao-Gabr window. Analysis results show that pronounced...
A new interacting multiple model (IMM) algorithm for maneuver target tracking is proposed in this paper. An adaptive updating method of the model transition probability is developed based on Bayes Theorem. Reinitialization strategies of the transition probabilities are design for two special cases. Then the updated transition probabilities are used to fulfill the interaction of the models. The proposed...
A new linear filter, the Converted Doppler Measurement Kalman Filter (CDMKF) has been previously presented to extract nonlinear pseudo-state from converted Doppler measurements (i.e., the product of the range measurements and Doppler measurements). Inherent in this filter is a non-Gaussian and more complicated pseudo-states noise, although the pseudo-states evolve linearly in time. A Gaussian mixture...
Combined with the space target observation radar application requirements, related issues of spaceborne MMW (MilliMeter Wave) InISAR (Interferometric Inverse Synthetic Aperture Radar) are researched. A proposed system contains an L-shaped orthogonal observation structure is designed and analyzed basing on a space-borne platform. The location of a space target can be acquired using imaging and interferometry,...
This paper investigates a sub-aperture imaging processing approach based on baseband azimuth scaling to resolve the azimuth spectrum aliasing problem in squinted sliding spotlight synthetic aperture radar (SAR). Squinted sliding spotlight model and the point target echo equation are established and azimuth spectrum is analyzed. The formula for calculating the sub-aperture length is also given to avoid...
For MIMO radar working in the same frequency coverage, the completely orthogonal waveforms occupied the same frequency coverage cannot be realistically found and used, which the cross-correlation noise among different waveforms is inevitable and may seriously reduce the radar performance. To address the aforementioned question, a novel algorithm based on oblique projection is proposed to separate...
We are going to develop a handheld wall penetrating SAR (WPSAR) to investigate the small shallowly buried objects such as thin wires, cables and so on. The WPSAR will be working very close to the wall surface, and the objects of interest sometimes buried inside the induced near-filed region of the probe. As a result, the traditional far-field SAR imaging algorithm cannot be used. Thus, a useful near-field...
This paper considers waveform design of orthogonal frequency division multiplexing (OFDM) signal for radar applications, which aims at mitigating the envelope fluctuation in OFDM. A novel method is proposed to reduce the peak-to-mean envelope power ratio (PMEPR), which is commonly used to evaluate the fluctuation. The proposed method is based on the tone reservation approach, in which some bits or...
In this paper, an integrated clutter-knowledge-based tracking (ICKBT) algorithm in realistic complex ground environment is presented, with the aid of the pre-existing environmental knowledge base and the amplitude information. The ICKBT has been proved in practice to be applicable. As the real radar data processing shows, the ICKBT algorithm can improve tracking performance influenced by the complex...
Spotlight bistatic forward-looking synthetic aperture radar (BFSAR) is a valid tool in the precise surveillance and attacking mission. Because the low frequency ultra-wideband (UWB) spotlight BFSAR has the complicated range-azimuth coupling, diverse imaging geometry, and long synthetic aperture, etc., the application of frequency-domain algorithms is limited. In this paper, an extended fast factorized...
With the rapid development of GNSS receiver's performance and the coming of each GNSS's Full Operational Capability (FOC), compatibility and interoperability must be one of the developing trends of GNSS positioning. In this study, a compatible Kalman filter was designed. The performances of the compatible Kalman filter (KF) and traditional Least Square (LS) were compared through BDS, GPS, and GLONASS...
This paper analyzes the various sources of the errors in the full link of the SAR satellite, and also studies the methods of the integrated error compensation for SAR. These methods mainly include the method based on the control unit, the method based on the measured data and the method based on the SAR echo data. This is an important reference for the high precision SAR imaging and data processing.
Precession is a typical kind of micro-motion of space targets such as ballistic targets. It has considerable significance to analyze the precession feature of ballistic targets in space target recognition and classification applications. A new idea using FMCW-ISAR (frequency modulation continuous wave-inverse synthetic aperture radar) system to extract micro-motion features is presented in this paper,...
Ground moving target indication (GMTI) radar utilizes Doppler frequency shift caused by the relative radial speed of target and the radar platform to distinguish ground moving target from surface clutter. But the radial speed becomes zero when the ground target is stationary or rotates around the radar platform. Then, the target measurement will be mistaken for surface clutter and removed, leading...
The information provided by netted-radar usually contains much more uncertainty, and counterintuitive results would be generated by D-S evidence theory with highly conflicting evidences. A model-modified D-S method is proposed in this paper, which can acquire rational fusion results when the evidences are highly conflicting. In addition, a two-level fusion structure is put forward to further eliminate...
The system is developed by use of IDE of the programming language Delphi XE3, the technology of MIDAS(Multi-Tier Distributed Application Service Suite) and the application of the structure of three-ties C/S(client/server) is introduced, which is based on it, and the centralized managerment for the process of the locomotive fittings overhaul is realised, so that the trustiness of the overhaul data...
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