MIMO radar DOA estimation method based on low-altitude multipath condition

Abstract

The invention discloses an MIMO radar DOA estimation method based on a low-altitude multipath condition, and belongs to the technical field of array signal processing. According to the method, firstly, the influence of reflected signals is considered, and a four-path echo signal model is introduced; and then a received signal is smoothed by using a bidirectional spatial smoothing algorithm to reduce the influence of the multipath signal; finally, a real number field generalized MUSIC algorithm and a multipath attenuation coefficient and generalized MUSIC joint estimation algorithm are theoretically analyzed, and then two spectral peak search forms are analyzed; the main difference is that a large spectral peak value generated by a zero angle is suppressed by using a limit criterion, so that the influence of a pseudo spectral peak is reduced, and the estimation performance under the low-altitude condition is improved. On the basis, a more reasonable weighting mode is used for improvingan original spectral peak searching mode, and experiments prove that when compared with an existing method, the method of the invention is higher in estimation success probability and better in performance.

Description

technical field [0001] The invention relates to the field of array signal processing, and is especially suitable for a method for estimating the direction of arrival of low-altitude elevation angles and high-precision waves for MIMO radars. Background technique [0002] In the anti-radar technology, low-elevation angles and ultra-low-altitude flight routes are often used when invading targets. At this time, due to the reflection of the ground during low-altitude flight, the radar echo signal, except for the radar emission signal, directly reaches the receiving array antenna after being reflected by the target. In addition to the direct wave, there are also reflected waves that reach the receiving antenna after being reflected by the ground and sea. If there is no special treatment, they will interfere with each other, resulting in multipath effects in the received signal, which will affect the accuracy of radar target estimation. At the same time, the multipath effect in the...

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Problems solved by technology

[0002] In the anti-radar technology, low-elevation angles and ultra-low-altitude flight routes are often used when invading targets. At this time, due to the reflection of the ground during low-altitude flight, the radar echo signal, except for the radar emission signal, directly reaches the receiving array antenna after being reflected by the target. In addition to the direct wave, there are also reflected waves that reach the receiving antenna after being reflected by the ground and sea. If there is no special treatment, they will interfere with each other, resulting in multipath effects in the received signal, which will affect the accuracy of radar target estimation. At the same time, the multipath effect in the received signal makes it impossible for the receiving end to receive accurate signals, resulting in a sharp decline in the calculation performance of the direction of arrival estimation algorithm based on subspace.

The signal reflected by the low-altitude target is transmitted through multipath, and the receiving array will not receive a single target reflection signal, but a coherent signal composed of multiple ground or sea surface reflection signals. When obtaining the covariance matrix, the covariance matrix will be The loss of rank is generated, and the low-altitude multipath problem has an impact on the performance of various direction-of-arrival estimation algorithms, resulting in poor performance of subspace algorithms and even failure to apply them.

The decoherence algorithm achieves decoherence and reduces the loss of the array aperture by performing conjugate flipping of the covariance matrix vector and then reconstructing the Toeplitz matrix to obtain the mean value, but ignores the influence of the pseudo spectral peak generated by the zero-degree angle on the DOA estimation. There will be a large deviation from the real data when the low elevation angle is estimated

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