Phase wrapping is a major problem in direction-of-arrival (DOA) estimation using phase-difference observations. For an antenna pair with an inter-antenna spacing greater than half of the wavelength ( $\lambda /2$ ) of the signal, phase wrapping occurs at certain DOA angles leading to phase-difference ambiguities. Existing phase unwrapping methods exploit either frequency or spatial diversity. These techniques work by imposing restrictions on the utilized frequencies or the receiver array geometry. In addition to these restrictions, sensitivity to noise and calibration errors is another limitation of these methods. We propose a grid-less phase-difference projection (PDP) DOA algorithm to overcome these issues. The concept of wrapped phased-difference pattern (WPDP) is introduced, which allows us to compute most of the parameters required for DOA estimation in an offline manner. This results in a superior computational speed in real-time compared to methods with similar DOA estimation performance. Simulation results demonstrate the excellent performance of the proposed algorithm, both in terms of accuracy and speed.

中文翻译：

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非均匀线性阵列的 DOA 估计：一种相位差投影方法

相位缠绕是使用相位差观测的到达方向 (DOA) 估计中的一个主要问题。对于天线间距大于波长一半的天线对（ $\λ/2$ ) 的信号，相位缠绕发生在某些 DOA 角度，导致相位差模糊。现有的相位展开方法利用频率或空间分集。这些技术通过对所使用的频率或接收器阵列几何形状施加限制来起作用。除了这些限制之外，对噪声和校准误差的敏感性是这些方法的另一个限制。我们提出了一种无网格相位差投影 (PDP) DOA 算法来克服这些问题。的概念引入了包裹相位差模式（WPDP），它允许我们以离线方式计算 DOA 估计所需的大部分参数。与具有类似 DOA 估计性能的方法相比，这导致实时计算速度更快。仿真结果证明了该算法在精度和速度方面的优异性能。