Hongming Liu

Binary orthogonal code design for MIMO radar systems

Multiple Input Multiple Output (MIMO) radar can effectively improve radar performance by transmitting specially designed orthogonal signals. A novel algorithm is presented to design binary orthogonal code for MIMO radar system. The proposed algorithm employs the Walsh function to maintain the orthogonal property of signals. The binary orthogonal code set is obtained by executing synchronal random exchange in column and random selection from rows to coding template, with using Genetic Algorithm (GA) for optimization. The simulation results show that the algorithm is feasible.

A PRACTICAL METHOD FOR RANGE MIGRATION COMPENSATION IN CHIRP RADAR

The echo signal characteristic of a chirp pulse train from a moving target is analyzed. It is pointed out that the range migration is caused by the migration exponential item (MEI) and can be compensated by removing the MEI. On this basis, we proposed a new practical compensation method with very low computation burden through shifting control on the matching weight coefficients. The parasitical sidelobes due to the quantization effect can be restrained effectively by storing multi-groups of weight. Simulation results proved the availability of the method.

CLEAN algorithm based direct-path-interference and multi-path-interference suppression in Bistatic MIMO Radar

Transceiver arrays of Bistatic MIMO Radar are separated in airspace, which transmit orthogonal signals in space, forming a wide, low-gain transmit beam. With the DBF technique, the receiver can form multiple integrated transmit and receive beams. As multiple orthogonal signals are transmitted, direct-path interference and multi-path interference are combination of multiple signals, and meanwhile, considering the correlativity of target signal and interference, the methods such as transmit nulling, sidelobe cancellation and subspace-projection are inapplicable. The method of CLEAN algorithm based direct-path interference and multi-path interference suppression is proposed in this paper with the characters of this radar and the lack of existing methods considered. This method suppresses the direct-path and multi-path interference, highlighting the weak target signal by stripping strong interference signals layer by layer. Simulation results prove the validity of the method.

Evaluation of the anti-interception method for MIMO radar

The performance of RF stealth is of significant importance for military radar because of the threat of an electromagnetic interference or an antiradiation missile. What is more, a useful method that can evaluate the RF stealth is needed urgently. In this paper, we proposed a method to evaluate the performance of RF stealth for MIMO radar. We provide a model to calculate the probability of intercept and analyze the factors that affect the probability of intercept. Simulation results show that the proposed model is efficient and valuable.

An analysis of anti-TDOA positioning capability for MIMO radar

The advantages of MIMO radar with orthogonal signals in anti-TDOA (Time Difference of Arrival) are discussed. First the cross-correlation between signals received by two receivers in different directions relative to MIMO radar is analyzed. It shows that the cross-correlation changes with the angle difference in certain value of which the two signals are even completely uncorrelated. Then a detailed analysis of angle-range coupling is presented based on uniform linear transmit array (ULTA) when Stepped Frequency Division Linear Frequency Modulation (SFDLFM) signals are used. The angle-range coupling will ultimately lead to the positioning deviation, thus contributing to the radar RF stealth.

Research on the mono-pulse phase comparison angle measurement algorithm of MIMO radar

Mono-pulse angle measurement technology is being widely used for its simple structure and high accuracy. In this paper, we propose a mono-pulse phase comparison angle measurement algorithm applied to virtual array transformed equivalently from MIMO radar. Based on the principle of improving the accuracy of angle measurement, we adopt amplitude weighting to optimize this algorithm that we achieve higher accuracy compared with mono-pulse phase comparison angle measurement algorithm applied to actual array of MIMO radar. Simulation results verify the validity of this algorithm.

Parameter selection of MIMO radar under the long time integration

Long time integration is a common work mode for multiple-input multiple-output (MIMO) radar. In this mode, the accumulation effect is seriously affected by range migration. To solve this problem, we derive an expression, which describes how the accumulation output changes with the target velocity, bandwidth, and other factors, based on the MIMO radar moving target echo model. This expression quantifies the relation between the range migration and the influence factors. It can be used to determine the range of the target velocity in which the motion compensation is needed. Further, through appropriate parameter selection, such as choosing a proper transmission bandwidth etc., the influence of the range migration on accumulation output is minimized. The correctness of the theoretical results is verified by simulations.

A model of non-coherent airborne MIMO space-time adaptive processing radar

Compared to single-input multiple-output (SIMO) radar, airborne multiple-input multiple-output (MIMO) space-time adaptive processing (STAP) radar transmits mutually orthogonal or non-coherent waveforms. The waveform diversity increases degrees of freedom (DOFs) of MIMO STAP radar and results in the variation of clutter characteristics. To make things worse, there exists many non-ideal factors in practical project that affect performance of MIMO STAP. Considering all such situations, we derive the covariance matrix of echo signals by utilizing waveform covariance matrix (WCM) and error covariance matrix tapering (CMT) to simplify the MIMO STAP in this paper. Signal to interference plus noise ratio (SINR) performance simulation results verify that MIMO STAP radar has a better spatial resolution than SIMO radar generally and improving in orthogonality of transmitting waveforms can obtain a better SINR performance.

A Method of Spectral Analysis Based on the Multistage Wiener Filter

Three different spectral patterns, including the MUSIC (Multiple Signal Classification), the LP (Linear Prediction) and the S-LP (Smooth Linear Prediction) methods using the unique recursion process of the multistage nested Wiener filter (MSNWF) for spectral analysis are described. These different spectral patterns can be provided simultaneously. Taking into account the computational advantages and different characteristics of the methods, a new scheme for spectral analysis is proposed, which is able to be adapted to either the continuous or the discrete spectrum cases.