Estimating the direction of arrival (DOA) information of a signal is important for communications, localization and navigation systems. Time-delay based methods are popular DOA algorithms that can estimate DOA with a minimal number of receivers. Time delay can be measured with subsample accuracy using phase-difference based methods. Phase-wrapping represents a major challenge for time delay estimation that occurs when inter-sensor spacing is large. Several methods exist for phase-unwrapping; the most successful methods are those search methods, which are time-consuming and do not lend themselves to theoretical analysis. In this paper, we present a phase-difference projection (PDP) method for DOA estimation which is capable of delivering more accurate results with reduced computational complexity. The proposed method has been tested and compared with several benchmark algorithms in both simulations and experiments. The results show that, at a signal-to-noise ratio (SNR) of -18 dB, using the proposed PDP algorithm, the percentage of the DOA estimates with errors smaller than <5° is 54%, and it reaches 100% at SNR =-7dB. This performance is not matched by the benchmark methods. For the utility test, we implemented this algorithm to realize an ultrasound-based air-mouse and it achieves satisfactory user experiences when using Google Maps, or playing some interactive games.
Chen, H., Ballal, T., Liu, X., & Al-Naffouri, T. Y. (2019). Realtime 2-D DOA Estimation using Phase-Difference Projection (PDP). 2019 27th European Signal Processing Conference (EUSIPCO). doi:10.23919/eusipco.2019.8902804