Method and device for converting an optical data signal from a multimode fiber to a corresponding signal into a monomode fiber

摘要

PCT No. PCT/SE92/00285 Sec. 371 Date Oct. 28, 1993 Sec. 102(e) Date Oct. 28, 1993 PCT Filed Apr. 29, 1992 PCT Pub. No. WO92/20172 PCT Pub. Date Nov. 12, 1992.The present invention discloses a method and a device for conversion of an optical data signal from a multimode fibre (1), which except for normal data signals may contain interruptions and an overmodulated low frequency signal, to a corresponding signal which is transmitted further into a single mode fibre (8) by a laser (7). An electric signal from an optical receiver (2) partly directly and partly through a low pass filter (4) is coupled to a comparator (5) the output of which modulates the laser (7). Upon detection of an optical interruption the low pass filter (4) is influenced such that its output signal is stored in a memory device, and the laser is influenced by diversion of the laser current, simultaneously as an analogue value in the control loop of the laser is stored. When the interruption ends both the laser transmitter (7) and the low pass filter (4) continue to operate as before on the basis of their stored analogue values.