A doa estimation method for mimo radar based on low-altitude multipath

Abstract

The invention discloses a MIMO radar DOA estimation method based on low-altitude multipath conditions, and belongs to the technical field of array signal processing. The present invention first considers the influence of reflected signals, and introduces a four-path echo signal model. Then use two-way space smoothing algorithm to smooth the received signal to reduce the influence of multipath signal. Finally, the generalized MUSIC algorithm in the real number domain and the joint estimation algorithm of multipath attenuation coefficient and generalized MUSIC are theoretically analyzed, and then the two spectral peak search forms are analyzed. Reduces the influence of spurious spectral peaks, thereby improving estimation performance at low altitudes. On this basis, this paper uses a more reasonable weighting method to improve the original peak search form. Experiments show that the proposed method has a higher estimated success probability and better performance than the existing methods.

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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