Abstract: Using the constant modulus (CM) property of the CDMA mobile communication signal, an online calibration algorithm, which calibrates the antenna array channel amplitude and phase errors using an auxiliary signal nearby the antenna array, is presented. Despreading the array receiving signal with the spread spectrum sequence being orthogonal to user's, and the coefficients of the channel FIR filter are then adjusted by CM algorithm adaptively to compensate the errors. Unlike the conventional self-calibration methods, it can be not affected by multi-path, and speeds up the convergence. Simulation demonstrates its validity.