In a method in a common observation receiver of a transceiver, a Transmitter Radio Frequency, TXRF, signal spectrum is received, a Receiver Radio Frequency, RXRF, signal spectrum is further received. Furthermore, a switching scheme is determined based on whether the type of the transmitter and the receiver is Frequency Division Duplex, FDD, or Time Division Duplex, TDD. Based on the switching scheme, the TXRF signal spectrum and the RXRF signal spectrum are switched into a switched baseband signal spectrum. By arranging a common observation receiver in a radio transceiver, and observing radio frequency signal spectrums, the transceiver may acquire knowledge about nonlinearities and other irregularities of applied components.