Optical emitter for common transmission of analogue and digital signals

摘要

An optical emitter for common transmission of analog and digital signals is specified which, although it has an optical transmission component (5) containing a laser, shows no increased bit error rate in the transmission of the digital signals as a result of so-called "clipping". Clipping, i.e. negative overdriving of the laser to below the laser threshold, which arises due to structural interference from the analog signal carriers, is prevented by a limiter (8) which is connected upstream of the modulation input of the optical transmission component (5). The limiter contains a time-variant network which applies a pre-defined minimum voltage to the modulation input whenever a comparator (7) detects that the modulation voltage has fallen below a pre-defined threshold.