| 摘要 |
A telecommunications system for optical transmissions, in particular optical transmissions in air or via optical fiber is described. The underlying idea of this invention consists basically in use of the data/ signal to be transmitted in order to modulate an IF sub-carrier which in turn modulates the laser. Therefore, the laser source is not modulated directly by the data signal but by an IF carrier that makes it possible to shift and, using a particular modulation technique, to reduce the band occupied. Accordingly, the modulation scheme used is of the OQPSK, FM type or any other type of constant power modulation scheme. The system is particularly immune to external interferences. |
