Optischer Sender zur gemeinsamen Übertragung von Analogsignalen und digitalen QAM-Signalen

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.