Phase difference estimation based on orthogonal signals for distributed coherent aperture radar

In distributed coherent aperture radar which is a new technology to replace traditional large aperture radars for next generation radar, all transmitted signals of unit radars should arrive at target at the same time and with the same phase so that the energy of all unit radars could be combined coherently. Therefore, the estimation of phase difference between signals at target is a key issue. In this paper, an estimation method of phase difference for distributed coherent aperture radar is proposed based on orthogonal signals. The mathematical model of phase difference is developed at first. And then, the estimation method of phase difference based on orthogonal signals is presented. In order to improve the estimation accuracy of phase difference, an improved design of orthogonal signals based on modified cost function is proposed. At last, simulations are carried out to illustrate the effectiveness of proposed method.