Height Measurement with Meter Wave Polarimetric MIMO Radar: Signal Model and MUSIC-like Algorithm

An Low-angle target tracking problem is investigated via the refined maximum likelihood (RML) algorithm. The results of the RML algorithm reveal that increasing the operating frequency of radar does not always reduce the mean-squared error (MSE) of angle estimate and thus an appropriate selection of the operating frequency can improve the angle estimation accuracy. Here, a frequency-agile RML algorithm is proposed, which adaptively adjusts the operating frequency during target tracking to minimize the MSEs of angle estimate. Theoretical analysis and simulation are made to verify the effectiveness of the frequency-agile RML algorithm.

https://ietresearch.onlinelibrary.wiley.com/doi/pdf/10.1049/iet-rsn.2016.0301

Low-angle target tracking using frequency-agile refined maximum likelihood algorithm

Meter wave radar height measurement is one of the most difficult problems in meter wave radar system. At present, the most popular height measurement methods of meter wave radar include beam splitting method, MUSIC algorithm and maximum likelihood estimation method, which can achieve good performance under flat ground. However, the real ground is not ideal condition, and the situation of undulating ground is also very complicated. Under this condition, the performance of the above algorithm dropped sharply. Many researchers solve this problem by improving the robustness of the algorithm. However, the authors think that the key to solve the problem is to establish a refined height measurement signal model. In this paper, the accurate model of reflection coefficient, reflection height and reflection point under the condition of undulating ground are established to provide accurate signal model for meter wave radar height measurement. Then we deduce the application of generalized MUSIC algorithm and maximum likelihood estimation algorithm for MIMO radar in the accurate terrain signal model. In fact, the method proposed in this paper is a terrain matching MIMO radar target height measurement, and the traditional algorithm can be regarded as terrain mismatch. The simulation results show that the accuracy of terrain matching estimation of the precise signal model established in this paper is much better than that of the traditional simplified signal model.

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Height Measurement With Meter Wave MIMO Radar Based on Precise Signal Model Under Complex Terrain

Hypersonic vehicle-borne radar target detection will suffer from time-varying plasma sheath which is formed during hypersonic flight. In this study, effect of time-varying plasma sheath on hypersonic vehicle-borne radar target detection is investigated. First, the radar echo model coupling time-varying plasma sheath effect is proposed using an analytical computation method. The regulation of electron density variation is based on flow parameters. Coherent integration result with the present of time-varying plasma sheath effect is derived. The degradations of hypersonic vehicle-borne radar target detection under time-varying plasma sheath are studied through real hypersonic vehicle flight cases. Simulation results shows that high electron density of time-varying plasma sheath will cause significant attenuation, which will lead to decrease of detection probability. In some cases, the signal-noise ratio (SNR) threshold that target can be detected increases more than 40 dB compared with situation without time-varying plasma sheath. Moreover, time-varying plasma sheath will cause time-varying amplitude and phase in pulse and between different pulses, causing intra-pulse and inter-pulse modulation phenomena. These phenomena lead to the disappearance of peak value in range-Doppler plane which will degrade the coherent accumulation as well as target detection performance. By using plasma sheath electron density diagnosis method on vehicle, compensation factor according to the electron density can be established to compensate plasma sheath effect in radar echoes. Simulations results based on real hypersonic vehicle flight flow parameters confirm the conclusions above. The work in this paper will benefit the design and application of hypersonic vehicle-borne radar in the future.

Effect of Time-Varying Plasma Sheath on Hypersonic Vehicle-Borne Radar Target Detection

According to the model of multipath propagation in low-angle tracking, the reflecting surface height has significant influence on the measurement precision of the target height. In this study, a novel method for the joint estimation of the target height and the reflecting surface height is proposed based on multichannel digital array radar. To reduce the computational burden of the proposed method, the projection gradient method instead of two-dimensional search is adopted to minimise the cost function. Moreover, the Cramer–Rao bound of the proposed method is also derived in this study. At last, simulations and practical data processing results show that the proposed method has a good estimation precision.

https://ietresearch.onlinelibrary.wiley.com/doi/pdf/10.1049/iet-rsn.2015.0391

Target and reflecting surface height joint estimation in low-angle radar

Clutter suppression and ground moving target imaging approach for hypersonic vehicle borne multichannel radar based on two-step focusing method

Joint optimization of PAPR reduction based on modified TR scheme for MIMO-OFDM radar

Low angle target estimation is always a difficult problem for radar elevation estimation Multiple-input multiple-output (MIMO) radar can increase array degree of freedom and resolution, and improv

Low angle estimation for MIMO radar with arbitrary array structures

In order to alleviate the model-mismatching and improve tracking precision of high speed strong maneuvering targets in near space, a new strong tracking filter algorithm with improved jerk model is proposed. The improved jerk model, in which the acceleration is assumed to be an exponential-correlated random process with non-zero mean, is used in the paper. Moreover, a fading factor is introduced in extended kalman filter tracking which can adjust covariance matrix adaptively and improve state estimation of the maneuvering target. Finally, the simulation results show that the algorithm improves the tracking performance of the high speed strong maneuvering targets in near space.

http://ieeexplore.ieee.org/iel7/7000957/7014954/07015320.pdf

Shenghua Wang

Papers

Target and reflecting surface height joint estimation in low-angle radar

Clutter suppression and ground moving target imaging approach for hypersonic vehicle borne multichannel radar based on two-step focusing method

Joint optimization of PAPR reduction based on modified TR scheme for MIMO-OFDM radar

Low angle estimation for MIMO radar with arbitrary array structures

Tracking methods of high speed strong maneuvering targets in near space