There is disclosed mechanisms for calibrating a homodyne receiver in a signal distribution network for time division duplex; a corresponding method is performed by a baseband calibration module. The method comprises acquiring a transmission signal being input to a homodyne transmitter of the signal distribution network; acquiring, from a heterodyne transmitter observation receiver of the signal distribution network, a first received version of the transmission signal; acquiring, from a homodyne receiver of the signal distribution network, a second received version of the transmission signal; and, calibrating the homodyne receiver using a comparison of the first received version of the transmission signal and the second received version of the transmission signal, using the first received version of the transmission signal as a reference signal, and using the transmission signal as a calibration signal.