A method for measuring the signal quality of an optical data signal is
provided. To measure the signal quality, and in particular the
signal-to-noise ratio of an optical data signal which has data-free time
intervals, the signal strength of the transmitted optical data signal is
measured during a data transmission. The signal strength of the noise
signal is determined during the data-free time intervals. The
signal-to-noise ratio is determined and used as a criterion for the signal
quality of the optical data signal.
