DEVICE FOR BIDIRECTIONAL SIMULTANEOUS TRANSMISSION OF DIGITAL INFORMATION

摘要

The device is used for simultaneous bidirectional transmission of information which originates from two information sources (11, 12) and is intended for two information sinks (21, 22). For this purpose, a single optical fibre (15), two transmitters (31, 32), two receivers (51, 52) and two directional couplers (17, 18) inserted into the fibre (15) are provided. In one transmitter (31), a laser (34) is located which can be directly modulated and in the other transmitter (32) a reflector (44) is located which forms an outgoing beam (R) from the incoming light beam (V) by reflection. The laser (34) is modulated in such a manner that intensity modulation of the beam V forms a carrier onto which the information signal is modulated by frequency or phase modulation. The second transmitter (32) modulates the beam R in direct intensity modulation. A filter (56) which blocks the frequency band of the carrier is used in the second receiver (52) to improve the signal-to-noise ratio. This filter can be constructed as a simple electrical low-pass filter.