Phase and gain of a transmit signal are measured at a transmitter by determining a first time delay having a first resolution at a measurement receiver between a reference signal from which the transmit signal is generated and a measured signal derived from the transmit signal by comparing amplitudes of the reference signal and the measured signal. A second time delay having a second resolution finer than the first resolution is determined at the measurement receiver between the reference signal and the measured signal based on the first time delay. The reference signal and the measured signal are time aligned at the measurement receiver based on the second time delay and the phase and gain of the transmit signal are estimated after the reference signal and the measured signal are time aligned.