ACCELERATED KEYING FOR AN OPTICAL COMMUNICATION SYSTEM

This invention relates to a binary signaling scheme for use in a transmitter comprising a semiconductor radiation source where the driving current and thus also the radiation output level is modulated by switching the driving current on and off. However, the modulation of the driving current is adapted to not wait for the radiation response to follow the complete rise or fall curve but to switch between two (or a larger number of) selected radiation output levels. During prolonged sequences of zeros (or ones), the driving current is switched to keep the radiation output level between a certain minimum and maximum level. This range of radiation output levels is adaptively selected in accordance with characteristics of the driving current, the optical transmission channel, the radiation source and/or the radiation detector.