Dynamic adjustment of the receiver gain during an MRI scan. To account for magnitude and/or phase distortions introduced by the receiver that are not necessarily identical at various receiver gains, a reference rf signal is applied to the receive chain by an additional antenna. Preferably the reference signal is adjusted such that its frequency lies at the border of the frequency band detected by the MR scan. Comparing the a priori known amplitude and phase of the reference signal with the amplitude and phase of the received reference signal allows to determine the distortions introduced at the respective receiver gain which are subsequently corrected. In a further embodiment, the reference signal is used to synchronize the modulation and demodulation units of a wireless transceiver system.