In a transceiver which is configured in particular for transmitting optical data, there is provided a device for reconstructing data from a received data signal (RX), having a clock-signal recovery unit (3) for recovering a clock signal belonging to the transmitted data from the received data signal, and having a data reconstruction unit (2) for reconstructing the transmitted data from the received data signal using the recovered clock signal (fCLK), and for emitting a data stream (DATA) which is synchronised with the recovered clock signal. A detector unit (9) detects an error state in the received data signal (RX) which prevents the data from being reconstructed reliably, switching means having a digital phase-locked lock (13) being provided to enable a signal having a clock rate which corresponds to the mean value of the clock signal (fCLK) previously recovered by the clock-signal recovery unit (3) to be fed, as a reference signal, to a phase-locked loop of the clock-signal recovery unit (3) in this event in place of the received data signal, thus ensuring that the phase-locked loop of the clock-signal recovery unit (3) will continue to oscillate properly even in this event.