In the signal processing for metrewave radar, the reflection paths of target echoes can cause severe error in the elevation estimation for the low-angle target tracking. The exact angles of the reflection paths are un...In the signal processing for metrewave radar, the reflection paths of target echoes can cause severe error in the elevation estimation for the low-angle target tracking. The exact angles of the reflection paths are unknown beforehand, and therefore, the reflection paths can not be suppressed easily. Therefore, in this article, an improved reflection paths suppression approach is presented. A block matrix aggregate is constructed based on the possible angles of the reflection paths. Combined with the beamforming-like processing, a generalized maximum likelihood estimation is derived to optimize the estimation. Moreover, the noise reduction method based on the Toeplitz covariance matrix is used for better performance. This approach is applied to the real data collected by the low-angle tracking radar with 8-channel vertical array. The experiment results show that the reflection effects are reduced and the accuracy of the elevation estimate is improved.展开更多
Based on Chen-Haus ' theory~[1] , an experimental research on the reflection of SAW from a short-circuited Au -grating on YZ LiNbO3 and a short-circuited Al- recessed groove grating on ST-X quartz is first present...Based on Chen-Haus ' theory~[1] , an experimental research on the reflection of SAW from a short-circuited Au -grating on YZ LiNbO3 and a short-circuited Al- recessed groove grating on ST-X quartz is first presented in this paper where an anomalous reflection phenomena existing in two gratings are confirmed. In addition, a residual reflection which couldn 't be completely cancelled by means of changing strip-thickness is pointed out for a short-circuited Au-grating on YZ LiNbO3 both experimentally and theoretically through extending Chen-Haus 'theory to anisotropic crystals.Finally, two kinds of IDT composed of single electrodes: Au-electrode on YZ LiNbO3 and Al-recessed - groove - electrode on ST-X quartz, are proposed for high internal reflection suppression. The experimental results of bandpass filters constructed with the IDTs mentioned above show a great improvement in passband distortion and a potential usefulness of new structure in high frequency range.展开更多
文摘In the signal processing for metrewave radar, the reflection paths of target echoes can cause severe error in the elevation estimation for the low-angle target tracking. The exact angles of the reflection paths are unknown beforehand, and therefore, the reflection paths can not be suppressed easily. Therefore, in this article, an improved reflection paths suppression approach is presented. A block matrix aggregate is constructed based on the possible angles of the reflection paths. Combined with the beamforming-like processing, a generalized maximum likelihood estimation is derived to optimize the estimation. Moreover, the noise reduction method based on the Toeplitz covariance matrix is used for better performance. This approach is applied to the real data collected by the low-angle tracking radar with 8-channel vertical array. The experiment results show that the reflection effects are reduced and the accuracy of the elevation estimate is improved.
文摘Based on Chen-Haus ' theory~[1] , an experimental research on the reflection of SAW from a short-circuited Au -grating on YZ LiNbO3 and a short-circuited Al- recessed groove grating on ST-X quartz is first presented in this paper where an anomalous reflection phenomena existing in two gratings are confirmed. In addition, a residual reflection which couldn 't be completely cancelled by means of changing strip-thickness is pointed out for a short-circuited Au-grating on YZ LiNbO3 both experimentally and theoretically through extending Chen-Haus 'theory to anisotropic crystals.Finally, two kinds of IDT composed of single electrodes: Au-electrode on YZ LiNbO3 and Al-recessed - groove - electrode on ST-X quartz, are proposed for high internal reflection suppression. The experimental results of bandpass filters constructed with the IDTs mentioned above show a great improvement in passband distortion and a potential usefulness of new structure in high frequency range.
