Time filter

Source Type

Bao Z.,Wuhan Early Warning Institute
IET Conference Publications | Year: 2013

The coherent processing interval in Over-The-Horizon Radar (OTHR) is usually set long to strengthen the weak signals, which increases the nonstationarity of the inference and make it more difficult to be restrained. In this paper, a piecewise beamforming method using multiple constraints to hold the coherence of the clutter is proposed. Comparing with the existing method with one constraint, this method can restrain the non-stationary inference and avoid the spreading of the clutter in more complicated situation. Simulation results illustrate the efficiency of the method.

Zhao Z.-G.,Wuhan Early Warning Institute | Chen J.-W.,Wuhan Early Warning Institute
International Conference on Signal Processing Proceedings, ICSP | Year: 2012

To remove the gain error caused by different waveforms and improve the performance of transmitting adaptive digital beamforming (TADBF), a reiterative matched filter (RMF) among different transmitted waveforms in Doppler domain is presented in this paper. Meanwhile, the drawback of RMF in time domain is analyzed. The simulation test shows that compared with the TADBF after matched filter (MF), the improvement of TADBF after RMF in Doppler domain on the quality of suppressing clutter is about 16dB. © 2012 IEEE.

Luo H.,Wuhan Early Warning Institute | Chen J.-W.,Wuhan Early Warning Institute
Yuhang Xuebao/Journal of Astronautics | Year: 2013

A comprehensive comparison of the existing ionosphere phase contamination correction approaches for sky-wave Over-the-Horizon Radar (OTHR) is made, and is evaluated from the view of correction efficiency, the universality of correction methods on different contaminations, the impact of phase contamination parameter change on approaches, the impact of SNR (signal-to-noise ratio) change on approaches and computational loads. The research lays the foundation for the practical engineering implementation and the improvement for the contamination correction methods.

Jun Z.Y.,Wuhan Naval University of Engineering | Feng L.R.,Wuhan Early Warning Institute | Liang W.Y.,Wuhan Early Warning Institute | Jian L.W.,Wuhan Early Warning Institute
Advanced Materials Research | Year: 2014

When detecting low-attitude targets, the angular accuracy of the meter-wave radar will descend because of the multipath reflecting from ground. Since multipath signals can be regarded as multipath jamming coming from the mainlobe, we propose an angle measurement based on the mainlobe multipath jamming suppression through differential constraints technique. The weight of the new approach is obtained through certain constraints on the sum-difference beams, which can suppress the jamming and keep the curve of the monopulse ratio unchanged simultaneously. Then form sum-difference beams and calculate the ratio of the monopulse ratio of the target. Finally, obtain the angle of the target through the determination of the smallest difference between the monopulse ratio of the target and the quiescent monopulse ratio. The method proposed in this paper can preserve good precision of the measurement angle. The result is verified by computer simulation. © (2014) Trans Tech Publications, Switzerland.

Zhao Z.,Wuhan Early Warning Institute | Chen J.,Wuhan Early Warning Institute | Bao Z.,Wuhan Early Warning Institute
2012 10th International Symposium on Antennas, Propagation and EM Theory, ISAPE 2012 | Year: 2012

With multiple-input multiple-output (MIMO) technique, skywave over-the-horizon radar (OTHR) is able to implement transmit adaptive digital beamforming (TADBF) to suppress multipath clutter or interference, which is a key technique in next generation OTHR. Time-staggered linear frequency modulated continuous wave and Doppler offset waveforms have been proposed in MIMO OTHR. However, both of the waveforms are constrained by Doppler ambiguity. To solve the problem, a slow time random phase-coded (STRPC) waveforms set fit for both maritime and aircraft surveillance in MIMO OTHR is proposed. And to detect weak targets submerged by cross- correlation peaks caused by strong clutters or large targets, a hierarchical waveform separation (HWS) is proposed. Simulation results are presented to verify the effectiveness of STRPC waveforms and HWS. © 2012 IEEE.

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