Wang Xiutan

Doppler distributed clutter model of airborne radar and its parameters estimation

To characterize the clutter spectrum center-shift and spread of airborne radar caused by the platform motion, a novel Doppler Distributed Clutter (DDC) model is proposed to describe the clutter covariance matrix in temporal domain. Based on this parametric model, maximum likelihood, subspace based method and other super-resolution methods are introduced into the Doppler parameters estimation, and more excellent performance is obtained than with the conventional approaches in frequency domain. The theoretical derivation and real experimental results are also provided to validate this novel model and methods of parameter estimating.

The structure and application of a new multi-DSP parallel computing architecture based on ADSP-2106x

Conventional radar signal processing systems have very limited flexibility because they are designed for their specific applications. For this problem, a general purpose high-speed radar signal processing system based on parallel computer architecture may be a hopeful solution. One of the key components in such a system is the processing node, which is chiefly responsible for the computation-intensive tasks. This paper presents a scheme of the processing node using a new multi-DSP parallel computing architecture as the hardware core. This architecture consists of five ADSP-2106x chips. It has many promising characteristics such as strong computational capability, broad I/O bandwidth, various communication methods, topology flexibility, and good expansion capability.

Parameter estimation of chirp signals using the metropolis-adjusted-Langevin's algorithm

This paper addresses the problem of parameter estimation of chirp signals in additive Gaussian white noise. A new Markov chain Monte Carlo (MCMC) method called the metropolis-adjusted-Langevins (MAL) algorithm is employed to solve this problem, which is faster to converge than the random walk metropolis-hastings (MH) algorithm. The initial values for the method are obtained by the discrete polynomial-phase transform (DFT). Simulations show that the Cramer-Rao low bound (CRLB) can be attained by the proposed method even at low signal-to-noise ratio (SNR) and the MAL algorithm is more efficient than the random walk MH algorithm.

New methods for estimating the center frequency and bandwidth of clutter

Two methods for estimating the center frequency and bandwidth, separately called centroid method (CM) and energy integration method (EIM), are proposed. A comparison of the complexity and the performance between the two methods and the general ones is presented. It is shown that the two methods are effective for short-time clutter data in practical application.

Built-in self-testing based on compressed 2-dimensional signature analysis

The design of modern electronic systems demands high system reliability and maintainability. In order to perform fault detection, localization and isolation effectively, it is necessary to design a built-in self-testing (BIST) module specific to the corresponding system. This paper presents a BIST method based. on compressed 2-dimensional signature analysis. The principle of compression and performance of test are discussed in detail. Using the presented method, a high faulty coverage ratio (FCR) can be achieved with a short signature compressed in both time domain and space domain. Theoretical analysis shows that this method is reliable and it can be easily implemented in hardware.

Digital image processing system for LLLTV

In this paper, the implementation of an image processing system for low-light-level TV (LLLTV) is proposed with some new algorithms. To process the low light image sequences in real time, there are three functional modules, noise removal, local contrast enhancement and global histogram adjustment, in pipelining structures, which fully utilize the device resources and make the system practical for real time applications. The algorithms used can remove mixed noise, including Gaussian noise and impulsive noise, and enhance the local and the global contrast. In the field experiment, the system has proved to be very effective to improve the image quality.

A new method for evaluation of jamming effect on ISAR

A new method was discussed for evaluating jamming effect for inverse synthetic aperture radar (ISAR) by using of relative entropy. Based on measuring difference of the image distributions with and without jamming, this method could be applied to both noise and deception jamming. Moreover, unlike traditional evaluating method based on correlation coefficients, the new method is not sensitive to image shift in azimuth caused by motion compensation of ISAR. Effectiveness of the new method is validated by simulation results.

A flexible baseband SAR ground moving targets simulator design and experimental results

A digital Synthetic Aperture Radar (SAR) simulator of ground moving targets is presented. Real scene data is used as the clutter background for fidelity and moving targets are real-time computed and embedded into scene data in time domain according to pulse repetition frequency (PRF). The experimental results prove the effectiveness of the system.

Partial Aperture Effect-Free Doppler Centroid Estimation Method for Airborne Side-looking SAR Based on Range-Doppler Domain Contrast Minimization

Based on the statistical property of the range migration (RM) in the synthetic aperture radar (SAR) range compressed range-Doppler (RD) domain, a Doppler centroid estimation method for SAR is proposed. The method can mitigate the partial aperture effect (PAE) which seriously degrades the estimation accuracy of the traditional Doppler estimators for high contrast scenes. Experimental results with real data of airborne high resolution SAR support the application of the proposed method to practical SAR processing.

Next generation radar signal processing system

In this paper, the leading characters, parallelism, programmability, scalability and reconfigurability of next generation high speed real-time radar signal processing systems are discussed in detail. Important design issues are studied. An experimental system underway is introduced.