Mao Shiyi

Tracking ground targets with road constraint using multiple hypotheses tracking

Data association in tracking multiple targets is of vital importance for airborne surveillance radar. Multiple hypotheses tracking (MHT) is generally accepted as the preferred method for solving the data association problem in modern multiple-target tracking (MTT) systems. However, there are usually too many hypotheses to process slowly. In this paper, map information has been used to prevent unnecessary MHT track branches and improve the state estimator. The simulation results show that this new algorithm improves tracking performance in realistic environment and effectively brings down the number of track branches, while reducing largely calculating time with better accuracy.

Method of moving target detection based on sub-image cancellation for single-antenna airborne synthetic aperture radar

Abstract The method of moving target detection based on subimage cancellation for single-antenna airborne SAR is presented. First the subimage is obtained through frequency processing is pointed out. The imaging difference of a stationary objects and moving object in the subimage based on the frequency division is analyzed from the fundamental principle. Then the developed method combines the shear averaging algorithm to focus on the moving target in the subimage, after the clutter suppression and the focusing position in each subimage is obtained. Next the observation model and the relative movement of the moving targets between the subimages estimate the moving targets. The theoretical analysis and simulation results demonstrate that the method is effective and can not only detect the moving targets, but also estimate their motion parameters precisely.

Optimal decision fusion with fuzzy priori probabilities

When a priori probabilities are fuzzy, the optimal decision fusion in the sense of minimum error of probability in a fusion center is considered. The fusion center receives decisions from various distributed sensors. The optimal decision fusion scheme at the fusion center is derived by using the URI (utility ranking index) and TDC (total distance criterion) fuzzy ordering criteria. It is found that the decision structure at the fusion center in this case is identical to that used by Chair and Varshney (1986) except that the threshold is different, and that an improvement in the performance of the system by using the presented schemes is achieved beyond that obtained by using the maximum membership degree (MMD) and maximum likelihood (ML) criteria.

Analytical performance evaluation of association of active and passive tracks for airborne sensors

An association algorithm for tracks generated by active and passive sensors was presented and its performance in terms of the probability of correct and false association was analytically evaluated by Farina and Miglioli (Signal Process. 69(3) (1998) 209). Based on the work in Farina and Miglioli, this paper concentrates on the derivation of simplified performance evaluation formula for deterministic target trajectories. The main contribution of this paper is: (a) the simplified formula of false association probability for a fixed value of correct association probability is presented, and (b) the simplified formula of correct association probability for a fixed value of false association probability is also derived. The advantage of the work is that the performance evaluation can be done with simple calculation instead of performing integral and using trial-and-error method. Numerical results and comparisons show that the presented methods are feasible and effective.

Design and implementation of a high speed vector processor for real-time SAR imaging

The VP (vector processor), designed and accomplished by ourselves, is an advanced processor, with BDSP9124/9320 as its main component. It can process 1M samples of data, and processing precision approaches the floating point processor. It could be applied for SAR (synthetic aperture radar) and other fields. The CSA (chirp scaling algorithm) is suitable for the VP calculation. Using the two-dimensional FFT to perform the CSA, the VP can remove corner turning memory and reduce processing overhead. Using the a large radix to complete the FFT, it can also reduce the processing time. The VP can produce a satisfactory image with high resolution, in right and squint side looking strip mapping.

Evidence combination based on evidence classification

A modified DS evidence combination method based on evidence classification (ECBEC) is introduced. Such a method imitates humans behavior in classification. When a series of beliefs are available, first those evidences are classified into several sets. In each set, all the evidences are consistent with each other and can be combined with DS rule reasonably. Then, all the combination results are integrated with weighting rule to form the final result. As shown in this work, such a method can solve the problem of combining evidence with high degree of conflict effectively.

Miss distance dynamics in active radar homing missiles

The combination radar homing systems with active terminal guidance are generally applied to advanced air-to-air missiles. Formulas of miss distance of active radar homing missiles due to measurement noise, heading error and target maneuver are derived, and the normalized miss distance curves are given. The effects of the seeker sampling time and the eclipsing of the target on the miss distance are analyzed.

Effect of Non-Appropriate Sampling on Radar Detection Algorithm

Many detection algorithms for received radar signals are based on Fast Fourier Transform (FFT) processing. The detection scheme for radar signals is affected by the prior knowledge of the Power Spectral Density (PSD), which is affected by non appropriate sampling. A performance comparison of two detectors based on frequency domain and changing place of sample namely periodogram and quadratic detectors, is presented, and analytic evaluation of the performance of these detectors supported by computer simulation is conducted. When the desired frequency is not in a bin of the discrete PSD, one standard technique to recover the peak is to add zeros (zero-fill). The performance measure utilized in this work is the Receiver Operating Characteristic (ROC), which measures the probability of detection with the probability of false alarm at different values of Signal to Noise Ratio (SNR). It is obvious that the performance will be degraded if there are estimation errors.

A Unified Imaging Algorithm for Multimode Spaceborne SAR

The new generation spaceborne SAR systems will be with high resolution and several work modes. In this paper, a unified imaging algorithm for multimode spaceborne SAR with the same chirp scaling processing core module was presented. Different pre- and post-processing steps were designed for stripmap, scan and spotlight work mode of spaceborne SAR. The same core module will make transplant and computation optimize of imaging processing platform more convenient. This unified imaging algorithm was validated through stripmap and scan mode raw data processing and point target simulation of spotlight mode.

Study on efficient computation and performance of AV-based reduced-rank filtering

In this paper, the complexity and performance of the Auxiliary Vector (AV) based reduced-rank filtering are addressed. The AV filters presented in the previous papers have the general form of the sum of the signature vector of the desired signal and a set of weighted AVs, which can be classified as three categories according to the orthogonality of their AVs and the optimality of the weight coefficients of the AVs. The AV filter with orthogonal AVs and optimal weight coefficients has the best performance, but requires considerable computational complexity and suffers from the numerical unstable operation. In order to reduce its computational load while keeping the superior performance, several low complexity algorithms are proposed to efficiently calculate the AVs and their weight coefficients. The diagonal loading technique is also introduced to solve the numerical unstability problem without complexity increase. The performance of the three types of AV filters is also compared through their application to Direct Sequence Code Division Multiple Access (DS-CDMA) systems for interference suppression.